It should come as no surprise that food, chemistry and mathematics meet in baking. For once I will leave the chemistry aside for a while and turn to the mathematical aspects of baking. More precisely I will delve into geometrical problems encountered in baking. When cutting cookies from a rolled out dough or placing cookies on a sheet for baking you actually attempt to solve a mathematical problem known as a packing problem. The purpose is to maximize the distance between the cookies and maximize the size of the cookies, paying attention that the cookies should not touch. Many will perhaps start with a square packing (see below), but soon figure out that a hexagonal packing will fit even more cookies onto the rolled out dough or onto the baking sheet (especially when the dough/sheet is large compared to the cookies). The optimum way of placing 2-17 circles in a square are shown below (and the solution for up to 10.000 circles is also available).

My challenge for you however is a different one as I’m interested in eliminating the leftover dough when cutting cookies. To achieve this the cookies cannot be circular. Using a square cookie cutter (or simply a knife) would be the easiest way to leave no gaps, but how cool are square cookies? What I’m really looking for are cookie tessallations which are aesthetically pleasing, and at the same time transferable to a baking sheet. Oh yeah: a tessallation “is the process of creating a two-dimensional plane using the repetition of a geometric shape with no overlaps and no gap” according to Wikipedia. So – no gaps – no leftover cookie dough!

Should you ever want to place circular cookies on a square baking sheet, this is how to maximize the size of the cookies! (Illustrations CC-BY-SA by Toby Hudson)

This is one way of solving the problem with leftover dough shown in the top picture. A tree can quite easily be transformed into a shape that fills the plane without any gaps. This image was made using the Tess software mentioned below.

Tessellations are frequently encountered in the art of M. C. Escher, and his Regular Division of the Plane Drawings are all based on tessellations. Most of Escher’s drawings however are not useful for making cookies because they are too interlocking – it would be impossible to take the cookies apart and transfer them to the baking sheet (and baking them “interlocked” would not be an option as cookie dough inevitably will raise/expand a little, making everything stick together). But I did find one example of an Escher inspired cookie cutter as well as some other nice examples of cookie cutters especially designed to make tessellations:

Over at Thingiverse the design file for this Escher inspired cookie cutter can be downloaded (Photo by Bas Pijls via Thingiverse). And should you want to transfer your own designs into a 3D printable format, check out this cookie-cutter-generator.

From Cox & Cox you can buy this Jigsaw cookie cutter (Photo from Cox & Cox product page). If you have access to a 3D printer you can also print your own jigsaw cookie cutter.

These elaborate cookie cutters are designed by Keith Kritselis. Over at Kickstarter you can find more information about his special cookie cutters for Halloween and Christmas. What makes them special is that each tessellation is made up of three or four different shapes.

If you rather want to make your own tessellations there are a couple of different software and online apps available, but I’ve found Tess to be one of the best. An evaluation copy of Tess (no save function) can be downloaded for free. Below are a couple of designs I’ve made. The patterns are nice, but would I want to each cookies with these shapes?

And finally the challenge for you all: Make your own cookie tessallations and share it! It’s not a competition, but rather an invitation to contribute. If the design is great I might have it 3D printed on a friends MakerBot or order it in metal from Shapeways and blog about it here If you send me a picture (preferably at least 620 pixels wide/high, email to webmaster/a/khymos.org) I’ll put up a gallery to display the submitted designs.

When I blogged about DIY mineral water last year it was mainly a theoretical exercise since I didn’t have the required salts at hand. My experience was limited to adding some baking soda (sodium bicarbonate) to water before carbonation. Luckily Paul Hinrichs tested the calculator! In the meantime I have purchased the required salts and with several kilograms in total I’m probably well stocked for the next decade! Based on the output from the calculator, I mixed the salts required to clone San Pellegrino, added water and carbonated the mixture. And the good news is that it works! The water tastes great and I’ve been enjoying cloned mineral waters every day now for the last couple of weeks.

Some changes have been made to the mineral water calculator (Updated! – scroll down for download options) since I last posted:

• a simpler worksheet more suitable for printing has been added
• more mineral waters have been added to the database, covering TDS (total dissolved solids) levels all the way up to more than 4000 mg/L
• potassium bicarbonate, magnesium chloride and calcium nitrate are made optional and can be left out if desired (it’s still a little unclear to me to what extent these can be detected at the typical levels found in mineral waters)
• one can now chose between using either hydroxides or carbonates of calcium and magnesium, depending on availability (it should be noted however that some waters high in bicarbonate may require the use of the hydroxides – not quite sure about this though)

A spoon full of mineral salts is required for the preparation of 1 liter of San Pellegrino mineral water.

Instructions for how to prepare the mixture of salts
Start by chosing the mineral water you want to clone from the drop down list. My advice would be not to start with the waters having very high levels of total dissolved solids (TDS) (except Kessel and Vichy Saint-Yorre since sodium bicarbonate dissolves easily). Aim for a TDS in the range 200-1500 mg/L (the list of all mineral waters in the rightmost worksheet is viewable and sortable). At the lower end you may not detect much mineral taste at all. At the higher end the mineral taste becomes quite pronounced. You can click the check boxes to include/exclude some salts. If known enter the composition of your tap water (your local water company should be able to give you these figures). I suggest that you weigh out the salts for 10 or even 100 liters, otherwise the amounts of salts will be in the low milligram or microgram range, requiring expensive lab scales. Mix the salts well. It may be god to start by mixing the salts present in the lowest concentrations first to ensure a homogeneous mixture.

How to make a cloned mineral water
Weigh out the approximate amount of salt (prepared as described above) needed for the amount of water that your carbonation vessel holds. At this point it’s doesn’t need to be very accurate, so if you have weighed it once you can simply need to remember which spoon you used and the size of the heap. Note that the different mineral salts vary greatly in density, so you should calibrate the heap used for each mineral salt mixture. Add the salt to the carbonation vessel and fill it up to the mark with water. The water will now turn opaque and whitish as the salts are suspended in the water (see picture above). Carbonate carefully and, depending on whether the water is high in carbonation and/or bicarbonate, try to hold the carbonation pressure for a couple of seconds extra before letting the pressure out. This allows a little more carbon dioxide to dissolve. Screw on the cap immediately to prevent the carbon dioxide from escaping. In some cases it may be necessary to repeat the carbonation step after some hours. Once the salts have dissolved (i.e. the water becomes clear) you can enjoy your very own home-made mineral water!

Several of the mineral salts have are not soluble in tap water, hence the opaque look to the left. After carbonation however they dissolve rapidly.

So far I’ve made up the salt mixtures for San Pellegrino (total dissolved solids, TDS: 1109 mg/L) and Gerolsteiner (TDS: 2488 mg/L). The first works like a charm, even when all salts are added simultaneously. This is possibly due to the high amount of sulfates which seem to dissolve more easily. Gerolsteiner is more tricky, partly due to the high TDS and the low amount of sulfate. I made it using carbonates instead of hydroxides, hoping that this would require addition of less carbon dioxide to neutralize the base. But after two days and 2-3 extra additions of carbon dioxide the salts had still not dissolved completely and this puzzles me. I certainly need to repeat this experiment. Darcy O’Neil states in Fix the pumps that the order of addition does matter. I’m not quite sure if that really is the case as most of the salts have a very low water solubility to start with, and the carbonic acid is the reason they dissolve. But maybe there is something I’m overlooking here? It could be that Gerolsteiner is easier to do with hydroxides, but Paul Hinrichs also had some trouble getting all the salts to dissolve for Gerolsteiner.

Some of the salts may be tricky to obtain, but the synonyms and links to Amazon below may be of some help:

• CaSO₄·0.5H₂O = Plaster of Paris (check availability from Amazon)
• MgSO₄·7H₂O = Epsom salt (check availability from Amazon)
• CaCO₃ = Chalk (check availability from Amazon)
• NaHCO₃ = Baking soda
• NaCl = Table salt
• Mg(OH)₂ = Milk of magnesia (check availability from Amazon)
• Ca(OH)₂ = Slaked lime, pickling lime, CAL (check availability from Amazon)

Before you head of to Amazon or some other place to order salts I should probably add some words of warning: make sure that the source you find is suitable for consumption! Some technical qualities of mineral salts may not be intended for food use, for instance due to the presence of heavy metals or other contaminants.

Note that some of the salts are available with varying amounts of crystal water. If you use other salts than those specified (i.e. anhydrous salts or salts with more crystal water) the molecular weights in the spreadsheet need to be adjusted for this. I guess that if you are familiar with the concept of crystal water, you’ll easily figure out the correct molecular weight and how to update the calculator according to the specific salts you chose to use.

Screen shot of the simple version, best suited for printing (see below for download options):

Screen shot of the complete version (see below for download options):

Calculator download options
Version 5 (latest update)
Excel: mineral_water_calculator_v5.xlsx (44 kB)
Open office: mineral_water_calculator_v5.ods (44 kB)

Version 4 (the version originally provided with this blog post – contains errors)
mineral_water_calculator_v4.xlsx

Mineral waters included
Mineral waters included in the database that comes with the calculator: Acqua Panna, Antipodes, Apollinaris, Aquarel Birken, Artificial mineral water, Badoit, Borsec, Burton (beer brewing), Calistoga, Carola Rouge, Contrex, Dorna, Evian, Farris, Fiuggi, Gerolsteiner, Harghita, Hassia Sprudel, Henniez, Kessel, London (beer brewing), Mountain Valley Spring, Munich (beer brewing), Neuselters, Perrier, Pilsen (beer brewing), PurPur (coffee brewing), Rosbacher Klassich, Saint-Yorre, Salvus, San Benedetto, San Narciso, San Pellegrino, Selters, Tea brewing (max), Tea brewing (min), Tesanjski Dijamant, Ty Nant, Vittel, Volvic, Voss, Waiwera. And you can easily add data for other mineral waters. The websites mineralwaters.org, finewaters.com and Mineral water atlas of the world have data for several hundred waters available. And if you have a bottle of your favourite mineral water at hand you only need to check the label to find the required input for the calculator.

Talking to a friend last year who is an avid home brewer made me realize how little I knew about beer and brewing. Inspired by what I learnt from the conversation I started reading Palmer’s How to brew which is essential for starters, but soon I also turned to Brigg’s Brewing – Science and practice and Priest’s Handbook of Brewing which are more rewarding if you’re a scientist. The first two steps in brewing beer – mashing and wort boiling – are really quite sophisticated extractions. And there is a lot of chemistry involved, so brewing beer seemed to me like an obvious extension of all my other interests. This is also the reason why I wanted to include a post about brewing in the Wonders of extraction series. The pictures for this blog post were taken as I brewed and bottled my latest batch, an American India Pale Ale.

Having read quite a lot about beer I soon found myself in the kitchen brewing my very first German wheat beer in August last year. I had decided that to familiarize myself with brewing I would try to brew with whatever equipment I had available in the kitchen. Mashing and lautering was done with a pasta strainer(!), and I boiled the wort in the largest pot I could find. While doing this it became very clear to me that these steps can be viewed as “reactive extractions”. Something is extracted and then something more happens! Given the simple method and equipment used I was totally amazed by the end result. And I quickly decided that this would not be my last batch of beer. After hours or reading (and making an important decision that I would like to spend my time brewing, rather than building the equipment) I finally settled with a Speidel Braumeister. This is a compact RIMS (Recirculating Infusion Mash System) type brewery system where a pump forces the wort upwards through the malt bed (different from a conventional RIMS system where the wort is allowed to drain through the malt bed by gravity). The picture below probably explains more than countless words.

The Speidel Braumeister is a compact RIMS type brewing system. During mashing a malt pipe is inserted. A metal screen and filter cloth at both ends of the malt pipe hold the malt in place. A pump forces the wort upwards through the mash (bottom left). After mashing the malt pipe is lifted out to allow the wort to drip of (bottom middle). Extra water may be added to rinse out remaining wort. The malt pipe is removed prior to the wort boiling (bottom right). Illustrations taken from www.speidel-braumeister.de

What really attracted me to brewing is that the range of ingredients available to professional brewers is also available to home brewers. And while a commercial brewery will do what it can to cut costs, opting for cheaper ingredients whenever possible, the money spent on malt, hops and yeast doesn’t really matter that much for the home brewer. As a result one can actually brew some very nice beers at home. And a much larger range of beers than is available in your next door shop. I believe this is quite different from what is the case for home brewing of wine (at least in Norway where fresh grape juice in those quantities is not available).

The extraction of sugars from malted barley is termed mashing. During mashing one utilizes the enzymes naturally present in grains to break down the starch to fermentable sugars (meaning sugars that the yeast can convert to alcohol). It sounds simple, but the process involves a number of enzymes with different temperature and pH optima. And one needs to do a couple of tricks for the enzymes to appear, so I will start with a brief introduction to malting (but feel to skip this and continue reading about mashing further down).

Malting
When a barley seed is wetted it will start to germinate. The release of the plant hormone gibberellic acid in the seed embryo sets of the synthesis of proteins capable of breaking down starch to sugar which will be needed for the seed to grow. These proteins are called enzymes, and they are extremely efficient at breaking down starch to sugar. After a couple of days the sprouted grain is air dried. As the water content decreases a second plant hormone, abscisic acid, is released. The effect is the opposite of gibberellic acid, and the synthesis of further enzymes is halted. The lowered water content also stops the enzymatic breakdown of the starch. The air dried green malt as it is now called is further kiln dried. The small amount of liberated sugar alongside the proteins allows for the Maillard reaction to proceed if the conditions are right, resulting in characteristic malt and caramel flavors as well as colors ranging from golden to brown and almost black. The darker the color of the malt, the less will be left of the enzymes required for starch hydrolysis (but this is usually not a problem as only a relatively small amount of very dark malt is used). Some enthusiasts malt their own barley, but most home brewers buy whole grain malt.

The hopper of my malt mill filled with ~5 kg malt is ready for some action (top left). As the grains pass the two rollers (bottom left) the malt is carefully crushed (bottom right). If crushed too fine the result is a “stuck mash”, if crushed too coarsely less sugar will be extracted and the yield drops.

Bottom screen and filter cloth inserted into the malt cylinder (top left) which is then lowered into the water filled brewing pot, crushed malt is then poured into the malt cylinder (top right), covered with a filter cloth (bottom left) and a metal screen (bottom right).

Mashing
The malt now contains starch as well as the enzymes required to break down the starch. When water is added and the temperature brought up to around 65-67 °C the enzymes start doing their job which is to break down the starch to sugars. This step is called mashing. Several enzymes are at play, but I’ll focus on the two most important: alpha-amylase and beta-amylase. Alpha-amylase is more temperature stable, attacks and breaks up the starch polymer at random places, resulting in smaller starch molecules known as dextrins. Only a very small fraction of the starch is converted to fermentable (= usable for the yeast) sugars by alpha-amylase. Beta-amylase on the other hand is less temperature stable but breaks down starch to maltose which is fermentable. By carefully choosing the mashing temperature the relative activity between alpha- and beta-amylase can be fine tuned. Mashing at 64-65 °C favors beta-amylase which yields a wort higher in fermentable sugars, resulting in a beer which is thinner, drier, higher in alcohol and has a lower final gravity. Mashing at 68-69 °C favors alpha-amylase which yields more dextrins which are not fermentable, resulting in a beer with more body which is sweeter, lower in alcohol and has a higher final gravity (i.e. residual “sugar” content). This may be confusing but trust me – it’s even more confusing when John Palmer tries to explain it with a garden allegory! I encourage you to check out the figure below which may help clarify things.  After mashing is complete the temperature is increased to 78 °C to inactivate the enzymes. The malt pipe is then pulled up to allow the wort contained in the malt bed to run off (termed lautering). The malt bed may be washed with 78 °C water (sparging) to increase the yield.

The wort is circulated upwards through the malt bed throughout the mashing time. At first the wort is very cloudy (top left) due to the fine particles from the crushing. The malt bed acts as a huge filter which helps remove particles, yielding a clear wort (top right). The time and temperature steps are controlled by a PID (bottom left). After mashing the malt cylinder is pulled up, the wort is allowed to run off (termed lautering) and the malt bed may be washed with water (sparging). The malt that remains is known as wet distillers grain (bottom right) and does wonders to your compost! Or you can use some of it for baking a special bread called treberbrot (named after the German word for spent grain).

If the extractable yield of a malt was 100% and the mash efficiency was 100% 1 kg malt would yield 1 kg of sugar in the mash. However, the extractable yield for a pale malt is about 80% (the hulls for instance are not extractable), and in my last brew I reached a mash efficiency of 78%. In effect I got approximately 624 g of sugar for each kg of malt.

Wort boiling
After mashing and lautering the wort is heated further and kept at a rolling boil for about one hour. There are several reasons for this. First the mashing enzymes are destroyed. Another one is to sterilize the wort (i.e. kill off unwanted bacteria and yeasts) prior to the following fermentation. Furthermore the boiling will allow some unwanted volatiles such as dimethyl sulfide to escape. The boiling will also facilitate the precipitation of proteins, resulting in a clearer beer. But perhaps most important for the resulting taste of beer is the addition of hops to the boiling wort. Hops are a kind of flowers that impart a bitter taste and in some cases also a significant aroma to beer. The bitterness balances the sweet taste of the wort, and the hops also stabilize and increase the shelf life of beer due to a mild antibiotic effect against bacteria that could otherwise ruin the beer.

Hops are typically added as whole cones or pellets as shown here. The pellets are crushed hop flowers that have been compressed for easier addition. Once added to the wort the pellets fall apart. The larger surface area of the fines results in a faster extraction of the alpha acids.

The hop cones contain alpha acids which are not particularly water soluble, and in fact not very bitter either. But when boiled they undergo a chemical change which makes them more bitter, the so called isomerization (shown below). Hops that are added for bittering of beer are typically added to the wort once it starts to boil as the extraction and isomerization processes takes some time. The extraction of alpha acids and the isomerization process are well studied and brewers can accurately predict and design the bitterness of a beer using online calculators. Required input data are wort volume, wort gravity (i.e. sugar content), alpha acid content in the hops and boil time as well as whether the hops are added as whole flowers or as fines compressed to a pellet. The hop bitterness is expressed in International Bitter Units (IBU), typically ranging from light lagers or wheat beers with 5 IBU up to India Pale Ales with 100 IBU or more. Those with access to a spectrophotometer can measure an approximate IBU of a beer by recording the absorbance at 275 nm and multiplying the number by 50 (IBU = A₂₇₅ x 50).

In addition to alpha acids hops also contain essential oils, some lighter, more volatile (primarily terpenes such as myrcene, linaol, geraniol, limonene, terpineol etc. – typically with a citrusy, green, grassy, floral aroma) as well as some heavy, less volatile oils (humulene, caryophyllene, farnesene – typically with a woody, spicy aroma). When smelling fresh hops it’s primarily the essential oils that make up the aroma. The majority of volatiles are lost from the boiling wort due to evaporation. However, if hops are added towards the end of the boil the less volatile oils will remain in the wort and in the resulting beer and impart a significant hop aroma to the beer (not to be confused with the bitter taste which results from prolonged boiling of hops). In some cases hops are even added to the wort during of after fermentation, so called dry hopping. This allows the extraction of the lighter volatile essential oils in the hops. In order to capture the lightest volatile oils it’s important to use fresh hops (i.e. hops that have not been dried). To complicate matters further many of these essential oils are quite reactive towards oxygen, and if digging deeper into the molecules behind a “hoppy” aroma one will find several oxidation products of the essential oils.

Here I should add that chefs probably could learn something from the early and late addition of hops to the boiling wort. I have a feeling that the early vs. late addition of spices and herbs has not yet been explored sufficiently. And just like the same hop contributes different “fractions” of its flavor depending on when it is added I also think that spices and herbs could contribute a broader range of aromas if they were not added all at once. I would be very interested in hearing your opinions on this! And hereby I also share an idea for a nice science project: Boil herbs/spices, take samples regularly and see how concentration changes with time. When does it reach a maximum? This would be very useful information for chefs!

The wort is boiled (top left) for several reasons, one is to extract and isomerize alpha-acids from hop cones into iso-alpha-acid which provide the important bitterness to beer. After boiling cold water is passed through a copper spiral (top right) to rapidly cool the wort (bottom left). After cooling the gravity (i.e. density) of the wort may be measured with a hydrometer (bottom right).

Towards the end of the wort boil some brewers also add some Irish moss to help clarify the wort. Interestingly this moss should be well known to the readers of Khymos, albeit in a slightly different form – namely as a white powder sold under the name carrageenan!

Dry Irish moss contains more than 50% of the polysaccharide carrageenan. When used in brewing the moss is wetted and allowed to hydrate before it is added added to the boiling worth the last 10-15 min.

The rest of the brewing process does not involve extractions, and hence is not the main focus of this blog post. But I’ve included some pictures to give you an idea of the different steps:

The cooled wort is sprinkled (top left) into the fermentation bucket to expose it to oxygen. For extra oxygenation an aquarium air pump can also be used to aerate the wort, resulting in some foam (bottom left). The added oxygen allows the approximately 100 billion yeast cells (top right) to grow/multiply before they move into anaerobic mode to produce ethanol from the wort sugars (primarily maltose). Proteins and hop residues are carefully left behind in the boiling vessel (bottom right).

Clean bottles are covered with aluminum foil prior to dry sterilization (top left). The fermented (and in this case dry hopped wort) is siphoned (top right) into a second bucket where it is mixed with the priming sugar need for bottle carbonation. The bottling device used here (bottom left) has a small valve which only opens once the bottom of the bottle presses against it, thereby reducing foaming during bottling. Labels are glued onto the bottles with milk.

After a minimum of 1-2 weeks bottle fermentation the American India Pale Ale is sufficiently carbonated for the very first tasting!

Previous blog posts on the Wonders of Extraction
Wonders of extraction: Water
Wonders of extraction: Ethanol
Wonders of extraction: Oil
Wonders of extraction: Espresso (part I) (sorry – no part II yet…)
Wonders of extraction: Pressure

In 2009 I wrote about my journey towards the perfect soft boiled eggs. Equipped with a formula I knew what I wanted, but it wasn’t so easy after all. Since then I’ve tried to model experimental data from Douglas Baldwin as well as data from my own measurements of egg yolk tempereatures when cooked sous vide (pictures of how I did this at the end of this blog post). I never got around to blog about the results, and now there’s no need for it anymore: The egg yolk problem has been solved! And the question that remains is: How we can utilize this in the kitchen?

The break through came this year with a paper by César Vega and Ruben Mercadé-Prieto entiteld Culinary Biophysics: on the Nature of the 6X°C Egg [1]. In my opinion it’s a brilliant example of molecular gastronomy: the results are practical enough for chefs and technical enough for scientists. This paper holds the key to unlock the true potential of egg yolk texture, and with it every chef can reproducibly prepare yolks with textures in the whole range between soft and hard. If you think I sound a bit exalted, you’re absolutely right.

Eggs cooked at low temperature have been all around the internet for the last couple of years, but a general feature of all these posts has been a focus on temperature. This has been the generally accepted truth. Even Hervé This in an interview with Discover magazine claimed that “Cooking eggs is really a question of temperature, not time”. But the present paper counters this. It’s main conclusion is that the texture of the egg yolk is a result of the time-temperature combination used, it’s thermal history if you like. If you’re interested in the details of the paper I suggest you jump directly to the pdf (I could download it for free some days ago, so give it a try), but if you’re only interested in the results, read on! A practical way to measure egg yolk texture is by using a rheometer. It’s a fancy piece of equipment that measures viscosity (and for those of you who are technically inclined – it measures viscosity as a function of shear rate). And what César and Ruben have done is to prepare a graph that shows the viscosity of a large number of temperature and time combinations. It’s a so-called iso-viscosity plot, meaning that once you have decided which viscosity you want the graph will show you all the temperature-time combinations that will give the desired result.

The figure shows how an egg yolk with a texture resembling one of the reference foods can be prepared by chosing any temperature-time combination along the respective plotted lines. (The figure is used with kind permission from Springer Science+Business Media: César Vega and Ruben Mercadé-Prieto in Food Biophysics 2011, 6:152-159, Culinary Biophysics: on the Nature of the 6X °C Egg, figure 8, page 158. The legend overlay has been added by me for clarity.)

For chefs, and even for chemists not working with rheology, it’s difficult to relate to numerical values of viscosity. To get around this the authors did a clever thing by measuring the viscosity of a range of semi-solid foods that may function as reference points: sweetened condensed milk, mayonnaise, honey, cookie icing and Marmite. You can use the iso-viscosity plot shown above to find different time-temperature combinations that give the same yolk viscosity. To use the plot, first decide which texture you want the egg yolk to have. Let’s say you’re in for a honey like texture (filled triangles). Pick a temperature, draw a vertical line until it crosses the line plotted through the triangles and then a horizontal line from there to the time axis. Repeating the exercise for different temperatures will give the different time-temperature combinations that all give a honey like yolk texture; in this case 310 min at 60 °C, 200 min at 61 °C, 125 min at 62 °C, 75 min at 63 °C, 55 min at 64 °C, 45 at 65 °C, 40 min at 66 °C, 26 min at 67 °C and finally 25 min at 68 °C will all do the trick. With a temperature controlled water bath one can chose whatever combination one likes, but if using a large pot of water and manually turning the heat on/off it’s advisable to cook the egg yolk in the lower temperature range. Also, the authors state that it requires a bit of practice to obtain different textures at temperatures above 66 °C.

The paper only deals with egg yolks. At the given time-temperature combinations the white will remain more or less runny. If only the yolk is to be used this doesn’t matter. But if serving the whole egg a simple way to set the egg white is to immerse the egg in boiling water for 2-3 minutes. Alternatively for a little longer at 85 or 90 °C. A comment made by Olly Rouse to my previous post on eggs suggests 8 min at 90 °C followed by cooling at 55 °C is perfect to set the white. However, if the eggs are to be “cooled” at 6X °C maybe 6-7 min is enough. What complicates matters even more is that at 6X °C convection inside the still runny egg white contributes significantly to the heat transfer, but I assume that this is negligible in combination with the longer cooking times in the lower 6X °C range.

Now that all possible egg yolk textures are available the question is: How we can utilize this in the kitchen? Apart from preparing soft boiled eggs, are there any applications in cooking? I’m sure there are many good ideas out there just waiting to be realized. If you blog or twitter about your ideas for utilizing precisely cooked egg yolks I suggest that you tag your blogposts with 6Xyolk and your tweets with #6Xyolk. Then everyone can easily follow up on the progress.

From my own experiments with measuring the core temperature of eggs cooked sous vide: The pictures show how I cut a thin slice from a plastic wine cork, pierced it with a philips screw driver, glued it to an egg, carefully pierced the egg shell with the same screw driver and finally introduced a thermocouple into the core of the egg yolk. There was enough friction between the thermocouple and the wine cork to allow the egg to be suspended by the thermocouple in the water bath. Temperature was logged using myPClab from Novus. Prior to the measurement the egg with the inserted thermocouple were left for several hours in the fridge for temperature equillibration.

[1] Vega, C.; Mercadé-Prieto, R. Food Biophysics 2011, 152-159. DOI: 10.1007/s11483-010-9200-1

Bruno Goussault started the sous vide master class at The Flemish Primitives 2011 by arguing that precise temperature or right temperature cooking is a better term than low temperature cooking. It’s really about knowing at which temperature the desired change takes place (or even better: knowing which time-temperature combinations will yield the desired results – this is a topic I will come back to soon).

Recounting the early days of sous vide, Bruno Goussault explained how he was once asked about how to produce prepare tender meat from a though cut. He was aware of a science paper on a slow cooking technique from USA (anyone know which paper this was?). It utilized a water bath, but the water washed away the juices. To avoid this Bruno wrapped the meat in cling film. A roast beef cooked at 58 °C turned out tender with a nice pink color. Then a friend working with plastics suggested that he should look into polyethylene (PE) bags in combination with a sous vide machine (boil-in-bag had already been around for some time apparently). Interestingly Bruno mentioned that during a recent Bocuse d’Or competition in USA where Bruno trained the American team, they replaced the plastic with a “skin” made from shrimps. Maybe we will see more “edible” skins used in sous vide in the future?

VACUUMING
Bruno then went on to talk about the vacuuming process and how time/pressure profiles should be adjusted to respect the shape and properties of the product, in particular when working with fish. A challenge with vegetables is the enzymatic release of ethylene, causing the bags to inflate (resulting in a poor heat conduction). The advice for vegetables and potatoes: use maximuum vacuum. But if you use the same setting for poultry the bones will turn out black because you extract bone marrow through the bones. Thus the vacuum should be sufficient to extract air from the bones, but not so high that the marrow is extracted.

Vacuum packing turns out to be a great way to impregnate food with flavors. As an example Sang-Hoon Degeimbre prepared oysters impregnated with champagne, cooked for 5 min at 83 °C and served with kiwi extract and an oyster leaf, Mertensia maritimia (Thanks Arielle!).

COLOR
When working with vegetables it is always the chlorophyll which causes problems (not the red/orange carotenes or the red/blue/purple anthocyans). This is due to the loss of the central magnesium ion. The easiest way to prevent this is by raising the pH. This can be done with baking soda (sodium bicarbonate), but gives an awful taste according to Bruno (and personally I would add that bicarbonate easily gives a mushy texture as well). A more advanced way to preserve the bright green color would be to add some other alkalizing/buffering agent such as sodium triphosphate (aka as sodium polyphosphate) or sodium hexametaphosphate (if you’re really interested, check out the paper Effect of pH on chlorophyll degradation and colour loss in blanched green peas for instance). And while we’re discussing color:  a side effect of the vacuum packaging of vegetables is that the air cells collaps, thereby reducing the diffraction of light which results in a darker and more intense green color.

Sang-Hoon Degeimbre shows how vacuuming gives greens a darker green color

STEPWISE COOLING
In restaurants sous vide is often used in a cook-chill-reheat fashion. For such a setup Bruno argued that it is vital to cool the meat or fish stepwise to allow a readsorption of the exudated juices (which also dissolve/carry away spices and Maillard products on the surface). If plunged directly into ice water fat and gelatin can cause the juices to gel, thereby effectively preventing a readsorption of the liquid. By taking the temperature down in a more controlled way the water holding capacity of fish/meat is improved and a portion of the exudated juice will be readsorbed (together with the flavors from the surface). A suggested stepwise cooling protocol for fish could be as follows: 10 min at room temperature, 10 min in cold water followed by 2 h in ice water. And it’s even possible to elaborate further on this – Bruno mentioned that he had developed a 4 step SV procedure followed by a 3 step chilling for Joel Robuchon. To me this also suggests that meat which is inteded for immediate serving should also rest a couple of minutes in the presence of the exudated juices. Would be interesting to know more about which factors influence this readsorption actually (maybe an interesting topic of a masters/PhD project?).

FISH
When preparing fish it is recommended to allow the fish to soak in a 5% brine for 10 min (Bruno lived for 3 years in Stavanger in Norway, and learnt this from a Norwegian chef during his stay – unfortunately he could not remember his name). This increases the osmotic pressure in the cells and prevents albumin from escaping (think of baked salmon with lot’s of white albumin leaking out) according to Bruno. After brining the recommended cooking times for a fish filet is then 1-3 min at 83 °C for pasteurization followed by 5 min at 58 °C for finishing.

Water baths set at 58, 66 and 83 °C. For a restaurant with only three water baths these are the recommended compromise temperatures.

TEMPERATURE
The many recommended temperature settings for meats and fish can be a challenge in a restaurant setting with a limited number of water baths. Bruno’s simplified approach was therefore to have three water baths at the following temperatures:

• 58 °C (and in any case below 62 °C): At 56 °C albumin is sill runny, at 58 °C it begins to whiten (and the overall color of meat is actually a result of seeing the red meat color through a white “fog” of albumin covering the muscle fibres. This temperature is recommended for fish and meat that is to be served red.
• 66 °C (in any case below 68 °C): The water holding capacity of the muscle tissue is dramatically reduced when heated above 68 °C. A temperature of 66 °C is therefore appropriate to retain the juiciness of meat. This temperature is recommended for poultry and well done meat.
• 83 °C (in any case below 85 °C): This temperature is suitable for vegetables as they need a temperature above 80 °C to be properly cooked, but at 85 °C pectin begins to hydrolyze so it’s important to stay below that temperature. This temperature is also suitable for a quick pasteurization of the surface of fish and meat.

Potatoes cooked for 3.5 h at 83 °C turn out really delicious.

HYDROLYSIS OF CONNECTIVE TISSUE
The hydrolysis of connective tissue was also briefly mentioned. For a though cut of meat such as shoulder or top blade 4 h at 100 °C are needed to break down the connective tissue. At 66 °C the same process takes 76 h, and further lowering the temperature to 56 °C will require a full 120 h for the similar break down of the connective tissue. But in return the low temperature gives a meat with a very nice color. Interestingly, Bruno mentioned that due to different aging practices a similar cut in the USA typically would only require 72h at 56 °C to reach the same tenderness! So the time/temperature combinations should only be used as rough guides.

Lamb cooked for 36h at 66 °C has a very nice texture!

Other tips & tricks:

• Rabbit and game are difficult to cook sous vide: sugar/glycogen in the muscles is converted into lactic acid which inhibits the cooking process (does anyone have more background information on this?)
• The boling point of water at 10 mbar is 6.9 °C. This is the reason why everything you plan to vacuum pack at this temperature should be cooled to below 6 °C, otherwise the liquid will start to boil in the vacuum.
• Regardless of what is cooked Bruno recommended a quick dip into a 83 °C water bath for pasteurization.
• It is better to generate Maillard flavors before sous vide cooking: the flavors will dissolve in the exudated meat juices and then be readsorbed by applying a proper stepwise cooling. If desired a short browning can be applied after sous vide cooking for crisping of the surface.

A very engaged Bruno sharing his knowledge about sous vide cooking

At the end of the session I got to chat a little with Bruno. He said that he was very happy about the wide spread use of sous vide, but also emphasized that it is a technique that can amplify mistakes as well as successes. -Many chefs don’t respect the temperature recommendations! I visited a chef who cooked meat at 54 °C and it smelled terrible, Bruno told me. The different bacterias can greatly influence the flavor of the resulting product if care is not taken to eliminate them. I asked Bruno about low temperature/long time combinations, but he said that chefs generally are not patient enough. They already complain that they don’t have time for the long sous vide preparations. Bruno does a lot of sous vide consulting for chefs and restaurants (in France/Europe through CREA founded by him in 1991 and in the US as a consultant for Cuisine solutions), but does not have big hopes for sous vide in home cooking: - No, it’s a gadget! Sous vide works best for cook & chill in a restaurant setting.

Thomas Bühner explaining how his “raw” meat jus is prepared. In the background the minced meat is being prepared.

(RAW) MEAT JUS
In the last part of the master class the German chef Thomas Bühner (La Vie, Osnabrück) demonstrated the preparation of meat jus (i.e. the natural juice given of by meat when heated). Ground meat was vacuumed and cooked for 2.5 h at 56 °C. The meat juice was then collected using a chinois and further concentrated using a rotary evaporator operated at 120 mbar and a water bath temperature of 40-50 °C (important to keep the water below the temperature of the sous vide water bath in order to retain the raw meat flavor). Compared to a conventional cleared stock the reddish meat jus is opaque. The meat jus is devoid of Maillard flavors due to the low temperature used, and this ensures a raw and bloody taste. The taste was interesting I would say, but perhaps not very delicious on it’s own … But I’m curious how it’s actually incorporated in his restaurant.

Conventional stock (left) and evaporated meat jus (right)

Thomas Bühner also demonstrated vacuum infusion using the Gastrovac. Potatoes were pierced/scorched, submerged in the truffle jus and then placed in the vacuum of the gastrovac. Thomas then repeatedly let air into the Gastrovac to allow cells to collapse and improve the impregnation.

The authors of Modernist Cuisine: Maxime Bilet, Chris Young and Nathan Myhrvold

In 2003 Chris Young had an epiphany of a meal at The Fat Duck outside London, and by the end of the meal he knew he had to work with Heston Blumenthal. Things worked out well and after a stage he was hired to build and lead the experimental kitchen at The Fat Duck. In 2007 he returned to Seattle to work with Nathan Myhrvold who at that time was very active on the eGullet forum sharing his research on the sous vide cooking technique. The project that started off as a book on sous vide eventually grew into Modernist Cuisine with 6 volumes spanning more than 2400 pages. After many delays (one being due to Amazon’s drop test which showed that the casing wasn’t sturdy enough for the books totaling 20 kg) Modernist Cuisine is ready for release in March, and will be presented at The Flemish Primitives event in Oostende, Belgium on March 14. That’s one more reason to visit the event!

Martin Lersch: Congratulations with Modernist Cuisine – it is a truly amazing accomlishment! Will you be present in Oostende?

Chris Young: Thank you. Yes, I’m very excited to be present at The Flemish Primitives to talk about our book, Modernist Cuisine, and to share the work of our team with the broader culinary community. I will have pages that I can sign and that Nathan and Max will have already signed.

ML: You studied mathematics and biochemistry, but how and when did your interest in food arise? And what made you want to combine this and approach food from a scientific perspective?

While at University, I came across an interesting book called On Food and Cooking, and it captivated me. Often, when I should have been studying science books, I was instead busy reading my copy of McGee. It made me realize how much I didn’t know about cooking. So I got to work filling in gaps in my knowledge, cooking my way through cookbooks such as Pépin’s La Technique and La Methode. But it was Thomas Keller’s The French Laundry Cookbook that kept me toiling away into the night perfecting my brunoise, skimming stocks, trussing chickens, braising short ribs, and thinking about becoming a chef.

In the autumn of 2001 I came to the self-realization that spending several more years pursuing a doctoral degree was not in my future. A reasonable question, then, was what should I do? With degrees in biochemistry and mathematics, there was every reason to believe that I was employable. The problem was, however, that I wanted to do something completely different, so I decided to get a job as a cook. Besides, I desperately needed to subsidize my hobby with a job. My grocery bill was getting out of hand! I hesitated only slightly before quitting academic pursuits for a job in a kitchen.

To a lot of my friends, this seemed like a bizarre decision. But for me it was an obvious choice: I had always enjoyed cooking, so I reasoned why not pursue it professionally? I figured that I would become a better cook and make some money at the same time. Well, I was right about the first part anyway. I was lucky to get a job with the talented chef William Belickis at Seattle’s Mistral Restaurant. William took a chance on a me when no one else in town new what to do with a scientist who wanted to become a chef.

But, as I like to tell the story, cooking seems to have been predestined. If my parents are to be believed, my first word was “hot”, uttered after I pulled myself up to the stovetop. As a toddler, my favorite toys were pots and pans. And when I was slightly older, I would attempt recipes from my mother’s encyclopedic set of Time Life’s The Good Cook series of books.

ML: I’ve heard that you had an epiphany of a meal at The Fat Duck outside London, and at the end of the meal you knew that you had to work with Heston. Could you tell me more about that?

The whole story is that at the end of the meal I asked for a stage at The Fat Duck. They said yes, and I returned to England at the beginning of April 2003 and stayed until the end of June 2003. Sometime in April, a newly hired chef failed to return to work, and another chef was scheduled to take a two week vacation. As a result, I ended up working as the garde manger chef. It was a really challenging job, but I loved it. It also gave me a lot of time to interact with Heston during service. He and I just kind of clicked. That June, he asked me if I wanted to move to England permanently and help him open a new kitchen that was focused on developing new ideas and techniques. How do you say no to that kind of offer?!

Getting a work visa turned out to be a bit of a challenge, no one had every tried to get a UK work visa for an experimental chef! So between July of 2003 and June of 2004 I commuted back and forth between Seattle and London. I would do experiments in my kitchen in Seattle and have phone calls with Heston every Sunday morning to discuss the results. Every two or three weeks I would fly to London, land at 7AM, take a taxi straight to the restaurant, and begin work! I would stay for one to two weeks before heading back to Seattle. This has to be some kind of record for commuting to work!

By the summer of 2004 the work permit was sorted out, and I moved to London with my girlfriend (now my wife). Around July of 2004 we opened the experimental kitchen in one of the garden sheds behind the restaurant. About six months later, Heston purchased the Hinds Head pub and I moved the experimental kitchen to a closet in the pub and then later to a house that was purchased with the pub. Located across the street from The Fat Duck, today that house serves as the prep kitchen (downstairs) for The Fat Duck and the experimental kitchen (upstairs). It’s actually a pretty nice kitchen to work in, but when I first moved into the space it was an empty room with broken windows and paint peeling off the walls. You could actually see through the floor into the rooms below!

Over the next 3 years we built up the experimental kitchen and expanded the size of our team as The Fat Duck became successful. For me, it was an amazing opportunity to be part of it from the beginning. I owe Heston a lot for giving me the opportunity to open and run the experimental kitchen, even when he didn’t know how he would pay for it!

ML: In a recent TEDx talk you mentioned that one of the things you learnt from Heston Blumenthal was what a talented cook can accomplish when enabled by science in the kitchen. Is it possible for a chef to really excel today without some scientific backing or a co-operation with a scientist?

Certainly it is possible for chefs to ignore science and still cook great food. Indeed, this is how we’ve cooked for most of history, and we humans have produced some pretty delicious food over the centuries. For me, the reason to be a scientifically-minded cook is for the creative possibilities it brings to the kitchen. Understanding the how’s and why’s of cooking inspires me to be a better chef; it gives me insights into cooking that help me make more delicious and satisfying food.

ML: How did you get in contact with Nathan Myhrvold?

The Fat Duck was where I met my co-author Nathan Myhrvold when he came for dinner. Because he lived in Seattle, and since I was more or less from Seattle too, we stayed in touch. We often exchanged ideas about Modernist barbecue-we’re both very passionate about great bbq-and other Modernist techniques. I would visit him whenever I was in Seattle. In July of 2007, I was thinking about leaving The Fat Duck. My son Jack had been born in April and my wife and I wanted to be a closer to home. I sent Nathan a friendly email telling him that I would be leaving The Fat Duck and that if he wanted to keep in touch he should use a different email address. Three minutes later, I received the following email:

> From: Nathan Myhrvold
> Date: Sat, 21 Jul 2007
> To: chris@thefatduck.co.uk
> Subject: Crazy Idea
>
> Why don’t you come work for me?
>
> Nathan

Later, Nathan told me about the book he had started working on and that I really should move back to Seattle and help him write it. It wasn’t a very hard choice, because even then I knew that this was going to be a once in a lifetime opportunity.

ML: Moving from The Fat Duck to Seattle and working with Modernist Cuisine, what was the biggest change?

One of the biggest challenges for me was writing everyday, rather than cooking. Cooking, with the goal of doing something new everyday, was something that I was comfortable with when I started this book. The writing, however, was a new challenge. Nathan and I really wanted to explain the how’s and why’s of Modernist cooking in a very approachable way; at the same time, we felt that we should not dumb down the relevant scientific concepts. This meant that we had to work very hard at explaining topics as clearly as possible, but in a way that wasn’t boring or irrelevant for a cook. We’ll find out if we succeeded!

ML: A couple of excerpts from the book have been published on the Modernist cuisine website and I must say that I’m stunned by the photographs. At what point during the project was it decided to move on from the ubiquitous black and white to a fully fledged art book?

Modernist Cuisine was never envisioned as being a black and white book. From the beginning, our entire team believed that this should be a no compromise book. We believed that the combination of beautiful photography, great writing, and clearly explained techniques and recipes would make this a unique cookbook that would capture people’s interest.

I will say that back in 2007, when I first started work with Nathan, we thought the book would be a bit smaller-perhaps only 400 pages!

ML: If I may paraphrase Sir Benjamin Thompson (aka Count Rumford), Which discovery in Modernist Cuisine will most powerfully contribute to increase the comforts and enjoyments of mankind?

Actually, I have no idea. This is one of the more intimidating things as an author, I have no idea how people will respond to Modernist Cuisine. I will be as interested as you are to see what ideas and techniques people gravitate towards. But more fascinating than what is in the book now, are the things we will discover need to be put into the next edition? So I suppose that the powerful contribution I hope our book will make is to inspire cooks and chefs to keep innovating and, thus, come up with ideas and techniques that are unknown today.

ML: With more than 2400 pages Modernist Cuisine takes a comprehensive approach to cooking. But in my R&D day time job I often find myself in the position that the more I know about something, the more questions I have. In which areas have you only yet scratched the surface?

Every chapter in our book could have been a lot longer. We tried to make sure we covered the most important points for each of the subjects we covered, but there were a lot of hard choices about what to leave out. At 2400 pages we obviously kept a lot in, but as you say, the more we researched a topic the more there was to know. That’s one of the great things about both science and cooking, there is no end to how far you can explore.

ML: For a student interested in modernist cuisine and molecular gastronomy, what would be good topics to dig into? Where are the white areas on the map?

I really think that we’ve just begun to scratch the surface of what’s really going on in the kitchen. So my advice to anyone would be to dig into the topics that interest you the most. Hopefully we’ll have given you a good idea of where to start looking, but you’ll quickly discover how much room there is to innovate. Very simply, terra incognito in the kitchen is lurking just about everywhere you choose to look.

ML: A majority of the papers published in food science journals deal with food safety, health issues, storage stability, etc. Are the practical questions that arise in cooking or eating not scientific enough for scientists to spend time (and money) on researching them? Or to put it differently – is the pleasure of eating still not a good enough reason for governmental money spending?

I think the unfortunate thing is that traditional scientists generally need funding to undertake their investigations, and, generally, the economic resources haven’t been available to enable them to explore the science behind the pleasures of eating. This was always something that saddened Nicholas Kurti, the renowned physicist who coined the phrase “molecular gastronomy” in an attempt to convince others that the pleasures of the table was a subject worthy of scientific research. Although Nicholas’ efforts certainly inspired chefs such as Heston Blumenthal and food writers like Harold McGee, it hasn’t changed the fact that most gastronomical research done by bonafide scientists has been done on their own time simply because they happen to be passionate about food and cooking.

ML: Sadly there have been no follow ups of the 2004 “International workshop on molecular gastronomy” in Erice. Do you see the need for such a meeting place today where scientists, writers, journalists, chefs and food enthusiasts can meet, eat and discuss in a truly creative and enthusiastic atmosphere? Are there any such meeting places today?

One of my personal regrets is that I was never able to attend one of the Erice conferences. It would be wonderful if someone could create an event that would bring together great chefs and scientists and foster collaboration between these two groups. Sadly, I don’t know of anything quite like this happening today.

ML: How does working at The Fat Duck and with Modernist Cuisine influence your home cooking when you opt for “comfort food”? What kind of dishes would you prepare?

Once upon a time I loved cooking elaborate, time consuming dishes at home. That’s kind of my day job now. So when I have the opportunity to cook for my family or for friends at my home I gravitate towards simple, but delicious things. In the summer I might barbecue ribs on a Sunday, in the winter it might be roasting a chicken or preparing a pot roast of pork. On the other hand, I have been known to do things a little differently in my kitchen than my neighbors-I do keep some liquid nitrogen around, which I use for everything from ice cream to preparing some pretty fantastic smoked ribs.

ML: Harold McGee has recently condensed his cooking experience into “Keys to good cooking”. It gives readers all the practical hints and tips for cooking. To what extent does Modernist Cuisine include practical hints and tips that chefs can use right away in the kitchen?

One of the design features of Modernist Cuisine are margin notes. We used these frequently to include bits of information that didn’t quite fit in the text and also as a way to include lots of practical cooking tips. An example of additional information is this margin note that shows up in one of our plated dish recipes for a beef rib eye:

Rib eye is not one muscle but three: loin (the eye), the deckle (cap), and the relatively unknown, but tender and delicious spinalus dorsi (see page TK). Many cooks know that the deckle is extra juicy and tender. This muscle is actually part of the deep pectoral muscle that is constantly exercised in life by breathing. This makes for a very tender, finely grained muscle (see page TK on why a well-exercised endurance muscle can be more tender). Unfortunately, because it sits on the outside of the roast, it is often overcooked. So it’s best to remove this muscle and cook it separately.

Some of these tips are things that a chef on our team discovered while working on a technique or recipe. For example, in our section on tofus, we have a margin note that explains that an alternative way to quickly make silken tofu is by hydrating 0.2% iota carrageenan and 0.1% kappa carrageenan in soy milk at 85 °C / 185 °F and then chilling it to set.

Some tips help explain how to use part of a recipe or technique in different situations, such as adapting a Russian-style smoked salmon to a Lox-style preparation by slightly modifying the cure.

We used margin notes liberally throughout the book, and we tried to include them with most recipes. In part, this was because we wanted to give people a reason to take the time to read through the recipes, even if they would never attempt a particular recipe because it seems too elaborate.

ML:I have no formal cooking education but I love to cook, and I’m very much looking forward to getting my hands on a copy of Modernist Cuisine. What in Modernist Cuisine do you think will be of greatest interest for the amateurs cooks?

I also started as an amateur cook, with no “formal” training. Modernist Cuisine is the book that I wish had existed when I became passionate and serious about my cooking in the late 1990s. So in that sense, Modernist Cuisine has a tremendous amount to offer any one who is enthusiastic about cooking.

Our book is not just about elaborate recipes prepared with exotic equipment, indeed much of what we cover can be done by anyone in their own kitchen with very little in the way of equipment. To me, the real value of Modernist Cuisine will be its ability to broaden and deepen a reader’s insight into the why’s and how’s behind techniques and recipes. Fundamentally, I believe that by explaining basic scientific principles that govern both traditional and Modernist cooking in a understandable and practical way will be the key to giving cooks greater creativity in the kitchen, regardless of what type of food they are interested in.

The Modernist Cuisine cooking lab in Seattle. Want more? Check out this 26-minute video tour.

ML: If you were to recommend three pieces of equipment/kitchen gear which each cost less than $500 to an amateur cook, what would they be?

First things first, you absolutely should have a good digital thermometer and scale. The thermometer should be accurate to at least 0.5°C (just because a thermometer will display a tenth of a degree doesn’t mean that it is accurate to a tenth of a degree) and the scale should be accurate to at least 0.5g, although 0.1g would be much better (but will obviously cost more). These two tools are as fundamental to me as a knife. Beyond these, I think a pressure cooker is a must. I use them for everything from stocks and sauces, to quickly transforming tough cuts of meat and plant foods into succulent dishes. A pressure cooker is not only a time saver in the kitchen, but can do delicious things that are simply impossible by other means of cooking.

ML: On an art-science axis, where is high-end cooking today? And where do you think it will be in the future?

Actually, this question presumes that art and science are independent of one another, which is something I personally disagree with. To me, science and art are both ways of exploring ideas, and new ideas are the currency of both scientists and artists. The confusion comes because people who have avoided science, or only experienced it in the boring environment of the classroom associate science with facts and structure, whereas they associate art with creativity and whimsy; but actually you need to be very creative as a scientist.

One of the joys I get from my work are applying both the scientist and the chef aspects of my personality. At face value it might seem like these methods of thought are at odds, but really they combine to be the catalyst of doing innovative work in the kitchen. Fundamentally, I believe all chefs are scientists at some level. It’s just a fundamental part of cooking. Anyone preparing a dish is conducting an experiment, which makes them a scientist in my view.

ML: With Modernist Cuisine hitting the shelves next month, is this it, or will there be a sequel?

Well, right now I’m travelling a lot to promote the book, as are Nathan and Max. But certainly there are a lot more areas of cooking that we’re interested in exploring. So, yes, there could be another book. But we’d like to see what people think of this one first.

ML: Chris, thank you very much for fitting this interview into your busy schedule!

Further reading: You can pre-order your copy of Modernist cuisine and while you wait for the books to arrive you can visit their website and blog for more information.

Update: I’ve written up a short post about no-knead bread in Norwegian – Brød uten å kna – to accompany my appearance in the popular science program Schrödingers katt.

I know – since the NY Times article about Jim Lahey in 2006 the no-knead breads have been all over the internet, newspapers and now even appear in numerous books – this is really old news. But the no-knead breads are really tasty as well, so I hope you’ll forgive me! When I give popular science talks about chemistry in the kitchen the one thing I’m always asked about is the no-knead recipe I show, so I thought it was about time to publish a recipe. Surely, everyone can google it – but regrettably many (if not most?) recipes are given in non-metric, volume based units – even Jim Lahey’s original recipe. And for baking this is really a drawback because the density of flour depends so much on how tight you pack it. Oh yeah, and I will also try to explain why and how the no-knead bread works.

The stretchy gluten which gives a dough its elasticity is formed when the two proteins glutenin and gliadin bind together. Kneading can speed up this process, but in a wetter dough the mobility of glutenin and gliadin increases, and given enough time they can actually manage it all by themselves. That’s why a wet dough needs time to develop the gluten network, but no kneading.

This is to show what 3 g fresh yeast looks like, in case you don’t have a balance that can accurately weigh such a small mass.

I’ve often seen it mentioned that a longer fermentation and/or less yeast gives a richer aroma. I think it’s true, but I’m not quite sure why this is the case. If the flavor compounds are produced proportionally to the carbon dioxide, the easiest way to increase flavor would be to up the amount of yeast. A lower temperature and/or less yeast would only mean that it takes longer to produce the same amount of carbon dioxid and flavor compounds. However, most of the advice I’ve seen about baking suggests that there is a flavor improvement by extending the fermentation time. So to rephrase the question: Why is the desirable bread flavor not proportional to the amount of yeast added? Some claim that the bitter flavor of pure yeast can dominate the flavor of the resulting bread if used at to high levels – but I have never been bothered by yeast flavor, even when using 50 g of fresh yeast for 1-2 kg of flour. But maybe I’m just insensitive to this bitterness? It could also be that the flavor profile produced by the yeast benefits from the lower temperature, but I doubt that one would actually be able to tell the difference in bread (you can easily tell the difference in beer, but here the fermentation may take from days to weeks – see also my post on Baking with hefeweizen yeast). Another possible explanation could be that enzymes, which are present in the flour or slowly produced by the yeast, contribute significantly to the flavor if given enough time. Amylase is one such enzyme which converts starch to sugar. It’s naturally produced by yeast, but it’s often added in pure form to “industrial doughs” to speed things up. Yet another explanation is that a long proofing time will allow a certain production of organic acids by the bacteria which are always present (this of course is what gives sour doughs their characteristic flavor).

The most unusual step in making no-knead bread is that it’s baked in a preheated heavy cooking pan, also known as a Dutch oven, usually made from cast iron. But this is indeed very clever! Professional bakers are lucky to have steam inlets in their ovens, because steam has a heat capacity which is much higher than that of dry air. Because of this the loaf will heat up quicker, giving a better oven spring. But the moist air inside the covered pan does more: as long as the loaf is colder than the pan the moisture will actually condense on the surface of the bread, thereby keeping it moist. This ensures that the oven spring is not hindered by a dry crust. Secondly, this moisture is important for a proper gelatinization of the starch: we are setting the stage for the Maillard reaction.

After about 30 min the lid is removed. At this point one will see the nice oven spring, but also notice that no browning has occured sine the temperature in the crust has been kept below the boiling point due the condensation of moisture on the surface. Once the lid is removed moisture can escape and the temperature in the crust rapidly rises above 110 °C where the Maillard reaction proceeds more rapidly. This is what gives the crust it’s nice brown color and also gives rise to the beautiful smell of fresh baked bread. At this point, the total baking time should be determined by the color of the loaf. When the surface is sufficiently browned your no-knead bread is finished.

Salt is very important, so don’t omit it from the bread. If you try to reduce the amount of salt in your diet – do so by eating less fast food and industrially prepared food. Don’t mess with the salt levels of home baked bread. It’s there for the taste, but it also improves the strength of the gluten network.

No-knead bread (based on Jim Lahey’s recipe)

390 g all purpose white flour
300 g water (77%)
7 g salt (1.8%)
~1-3 g fresh yeast

Mix everything until the flour is completely moistened. Cover and leave for 15-25 hours. Pour onto a floured surface, fold 3-4 times, shape rapidly into a boule, place it on a generously floured cloth/towel seamside down and proof until doubled in size (~2 hours). Dump seam side up into a cast iron pan preheated to 230 °C and bake with the lid on for 30 min. Take the lid of and bake until the crust has a dark golden color – approximately 15 min.

Proofing the loaf on well floured towel

The percentages in the recipe are so-called Baker’s percentages, giving the amount of the ingredients in percent of the flour. The amount of water is often referred to as the degree of hydration. I’ve had good results with a hydration of 77%, but you may want to adjust this depending on your preferences. In fact, it’s impossible to know exactly what hydration Jim Lahey used because of his volume measurements! The recipe posted on the Sullivan Street Bakery’s homepage has a hydration of 80%, but I wonder whether the amounts are calculated or measured. My advice is to start at 77% and then adjust up/down in the range 75-80%. By adjusting the hydration you will indirectly also adjust the size of the pores (more water = larger pores) and the moistness of the bread. The higher hydration will of course yield a more sticky dough, but don’t forget that it’s a no-knead bread, so you’re supposed to handle the dough as little as possible.

Regarding the amount of yeast I’d start with 3 g, but if you feel that it rises to quickly you can lower this to 1-2 g. The main reason for this variability is that the activity (= number of living yeast cells) of fresh yeast decreases with time. Homebrewers can calculate exact pitching rates for yeast based on a ~5% loss of viability per week for liquid yeast. My guess is that compressed yeast is more stable, but I haven’t been able to find any data on it’s viability.

My no-knead breads look a bit different every time I bake them, but that’s OK.

The required hydration depends a lot on flour as well of course! No-knead breads can greatly benefit from substituting some of the white flour with whole grain flours, or ancient cereals such as emmer (farro), spelt, einkorn etc. Whole grain flours tend to bind more water though and develop a less strong gluten network. This last point is well illustrated by my failed attempt to bake a no-knead bread with 100% emmer. The resulting flat loaf is shown in the picture below.

No-knead bread with 100% emmer did not have a sufficiently strong gluten network – the bread ended up very flat…

Further reading:
The Secret of Great Bread: Let Time Do the Work (original NY Times article)
No-Knead Bread (original recipe from Jim Lahey)
Soon the bread will be making itself
Simple Crusty Bread (recipe)
No-Knead Bread: Not Making Itself Yet, but a Lot Quicker
Speedy No-Knead Bread (recipe)
Fast No-Knead Whole Wheat Bread (recipe)
eGullet thread on no-knead breads

A little more than a week ago Dave Arnold posted a great, new technique: pressure infusion using a conventional iSi whipper! Just think of it – the whipper has been around for decades, and years a go Ferran Adrià pioneered it’s use for espumas. Several have suggested it’s use for carbonation of fruit. But no one had thought of utilizing the whipper for infusions – until August 11th when Dave Arnold of Cooking issues posted the results of his experiments in “Infusion Profusion: Game-Changing Fast ‘N Cheap Technique”. The first blogger to pick up the technique and post about it on August 12th was Linda of playing with fire and water who termed it a revolutionary technique. A couple of days later, on August 17th Aki and Alex of Ideas in food posted a combined pressurized infusion of basil and marination of mozzarella. And then on August 20th James of Jim Seven describes his results comparing conventional cold brewed coffee to cold pressure brewed coffee. It’s really fascinating how fast the idea spread, and it illustrates the benefits of an open and sharing approach to food innovations.

The science behind this is quite simple: in the pressurized canister nitrous oxide (N₂O) dissolves and penetrates the food. When the pressures is suddently released (and it is important to release pressure as fast as possible) the sudden pressure drop causes the dissolved gas to nucleate and form bubbles which expand and disrupt cells, thereby releasing flavor compounds. The physical phenomenon is known as cavitation.

A single N₂O charger contains 8 g of gas corresponding to 0.1818 moles or a volume of 4.1 L at 25 °C and 1 atm pressure. The volume of the chargers is 0.01 L which gives an impressive initial pressure in the chargers of 445 atm! With an approximate volume of 0.7 L the pressure in an empty whipper charged with a single charge would be nearly 6 atm. When liquids are added the volume decreases, but the effect on the head pressure will depend on the type of liquid added. The solubility of N₂O in water is 0.15 g/100 mL at 15 °C, meaning that with 100 mL of water, the head pressure would be roughly 10% higher than in an empty canister (that is, if the solubility is independent of pressure – I’m not quite sure about this). However, since N₂O is a rather non-polar molecule the solubility in ethanol or even oils is much greater than in water, with a resulting lower head pressure. But since flavor delivery is mediated by the dissolved gas suddenly nucleating and bursting cell structures, infusions using ethanol or oil will actually be more effective than those with water because more gas can be dissolved in these solvents (besides the fact that ethanol and oil are better solvents for flavors than water).

Thinking about how I could utilize the pressure infusion technique I came to think about the problems I ran into with hay like off flavors in the parsley and banana flavored marshmallows I made for TGRWT #2. The off flavors can be traced back to 3-methyl-2,4-nonanedione which likely stems from oxidation of unsaturated fatty acids or polyenes. Crushing parsley inevitably leads to oxidation (possibly also enhanced by mixing intra and extra cellular comounds/enzymes), but with pressure infusion – practically in the absence of air – seems to be much gentler than crushing according to Dave’s initial report (as judged by color). So I did a quick experiment with this, infusing a couple of sprigs in 2 dL of water for about 2 minutes. This was by no means enough, and the water had only a faint aroma of parsley (vodka would of course have been much better for the flavor extraction). But it was a clean parsley aroma, and the water was perfectly clear.

I have spent lazy summer days in a “Sommerhus” (e.g. “summer house”) in Denmark with my family and one thing I will share with you is the coffee I enjoyed every morning. My wife doesn’t drink black coffee, so to keep things as simple and easy as possible I brought my Aeropress and a glass of preground coffee (for obvious reasons I decided not to bring my coffee grinder, but I did use a nice coffee from Tim Wendelboe though). At home I have enough equipment to prepare coffee in a dozen ways, but none are as simple and fast as the Aeropress (well – maybe except for Nescafe, but does that count?). I would even dare to say that no other method of preparing coffee offers a better quality-price-convenience ratio!

Although it’s simple, you can still vary grind, amount of water, water temperature and extraction time, so there are plenty of possibilities for experimentation. And believe it or not – there is even an Aeropress world championship. That should give you an idea of how much variation is actually possible!

Using two measuring spoons and the suggested 30-40 second brew time gives a somewhat overdosed and underextracted coffee according to my taste (i.e. a lot of “coffee” aroma, but too little bitterness and a little flat tastewise). This of course also depends a lot on the density of the coffee – and here we’re back to why volume measurements are quite useless for dosing powders. After some experimentation however I’ve ended up with a dose around 15-20 g (ground at setting 40 on my Rancilio Rocky) and extraction times in the range 40-90 seconds. But these conditions are not carved in stone – I keep adjusting them as I get different coffees, and also enjoy how my coffee tastes a bit different every morning. You can get further input on the Aeropress recipes from previous AWC competitors.

Apart from the nice coffee, the best thing about this coffee maker is that it’s very easy to clean. Because of that it’s also the ideal coffee maker to use in the office or at work (in case there’s no good coffee available there). Here are some pictures to illustrate preparation of a cup of coffee and cleaning of the Aeropress:

Areopress upside down on countertop, loaded with coarsly ground coffee (I dialed my Rocky to around 40).

The advantage of the “inverted” method is that no coffee starts to drip before you want it to.

I stir to make sure all the coffee is properly wetted. I then screw on the filter holder with a filter paper inserted (not shown here). Also note that I fill it up all the way with water, and I usually use freshly boiled water. Some prefer to use less water and temperatures anywhere between 75-95 °C.

Oooops – not a perfect fit with the mugs in the summer house, but this did in no way affect the taste of the coffee With the mugs/cups I use at home there’s no problem. After extraction I top of the cup with hot water.

After the filter holder is unscrewed, pressing the plunger the last few millimeters makes the filterpaper and the filtercake pop out of the cylinder. You would of course normally just pop this directly into your waste bin, not on a clean plate as in the picture …

Quickly rinse your Aeropress under running water – and you’re done!

If I were to name a topic for this year’s Flemish Primitives event I guess gadgets would be it. I’ve already covered the high pressure processing in a previous post. Regrettably we were only shown pictures and movies of this machine (it is to large/complex to be brought on stage) but there was much more that would qualify for a post focusing on some of the gadgets presented.

Crycotuv
The most obscure machine in my opinion was the Crycotuv – a vacuum chamber which could be cooled to any desired temperature between -150 and 0 °C in seconds/minutes. The rapid cooling was achieved by evaporation of liquid nitrogen (so in order to run a Crycotuv you’ll need a steady supply of LN2). The major benefit of rapid vacuum freezing is significantly less cell damage. In conventional freezing the damaged cells cause leaks when the food is thawed. When the desired vacuum was reached, a spray nozzle also allowed flavors to be sprayed onto foods inside the vacuum chamber, resulting in a “vacuum impregnation”. This was demonstrated with oranges slices which were submerged in coffee. Using the Crycotuv the airpockets were replaced by coffee.

(skip the long intro with overly dramatic music and view from 0:53 – that’s were the demo starts)

The most interesting demonstration was how one could use the vacuum to expand foods and then freeze them to obtain sponges. This was done with foie gras and I sure wish I could have tasted one of those! The Crycotuv is based on a ideas from Kristof Coppens and produced by Messer, and during the sessions the Jean-Claude Claeys and Harold Demoen (from Messer and Cretel respectively) were also on stage.

During the presentation is occured to me that the vacuum impregnation (without cooling) is identical to what you can do with the Gastrovac, and that you could even make a DIY version with a pressure cooker and a water suction pump. Or if you have a food saver with the possibility of attaching jars you can use them as well for vacuum impregnation.

Chef Roger van Damme with the EmulsionFire. Photo by Piet De Kersgieter.

EmulsionFire
An immersion blender will bring you quite far when making emulsions such as mayonnaise, but if you want to make emulsions at a larger scale the EmulsionFire could be your choice. The machine was demonstrated by chef Roger van Damme and 3 emulsion samples were handed out to every participant – they were indeed thick and very rich. In fact, it’s possible to make emulsions as thick as Nutella with EmulsionFire. It was mentioned that the machine uses magnets, but no details were given on this. My guess is that the machine uses a contact less, magnet based drive train in the emulsifier unit as would probably be qutie favorable from a cleaning viewpoint – but this is only a guess.

Samples prepared by the EmulsionFire: dark chocolate, milk chocolate and coconut creams.

Laboratory equipment
The large laboratory supplier VWR was a sponsor of the event and had a range of equipment on display at the back of the scene. I talked to the VWR sales representative Dominique Mauroy and he let me know that they soon will launch a brochure with laboratory equipment of particular relevance for use in the kitchen. I’ll update once I know more about this. There is also a launching event planned on April 19 in Belgium. Anyway – here are some of the gadgets VWR had on display. This is equipment that we use daily in my daytime job, and it’s really fun to see how it has found it’s way into kitchens.

To the left a conventional rotary evaporator, but check out the wide mouthed flask on the right! This is perfect glassware for food stuffs which are sticky and may require more extensive cleaning.

In chemistry labs UltraTurrax stirrers are a common sight. They are high shear stirres but without “external” moving parts (like the knives of an immersion blender) and are excellent for dispersion of hydrocolloids.

Freeze driers (left) are well known in the food industry, but chefs are also beginning to see the potential that lies in this low temperature flavor concentration technique. Of course there were also water baths for sous vide on display.

To the left a standard laboratory heating plate with magnetic stirring. To the right magnetic stirring bars of different sizes.

SOSA aroma library
SOSA should be well known to many with their extensive product range for professional kitchens. At The Flemish Primitives this year they displayed their aroma library. With a total of 192 flavors grouped into categories such as sweets, nuts, herbs, flowers, vegetables, roots, fiction, lactis etc you basically have “an alphabet of flavors” at your hands. It’s a great way of learning flavors and a perfect toolbox when investigating flavor pairings. I’d sure like to have a library like this in my kitchen! Interestingly Sense for taste (who formally run the foodpairing website) and SOSA had co-published a small booklet on flavorpairing with two recipes using some of the flavors from the “flavor alphabet”.

“Alphabet of flavors” from SOSA: 192 flavors at your finger tips!

Wine table
And finally a gadget for the more tech savy people: a Microsoft Surface table running a wine application (from the company Metanous). As you can see from the pictures and the video a coaster with an identifying chip is attached to each wine bottle. When the bottle is put down on the table it is immediately recognized and a circular menu appears around the bottle. If you move or rotate the bottle, the menu follows the movements. The menu gives access to text, pictures and videos about the wine, the grape variety, the growing region, interviews with the wine producers etc. The table allows plenty of simultaneous user interaction with different gestures and touches.

Due to the outbreak sessions I regrettably missed the presentation of Sergio Herman’s sophisticated dinner plates.
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I also visited The Flemish Primitives in 2009. You can read more about that in my four posts from last year: The Flemish Primitives: A travel report (part 1), Chocolate surprise (part 2), Heston Blumenthal (part 3) and Glowing lollipops (part 4). Final note to readers: This year my travel expenses were covered by TFP and the tourism bureau of Brugge.