In Japan eggs cooked in hot springs (onsen) are known as onsen tamago. I’ve also read that Māori women used boiling pools at Whakarewarewa to cook. In fact I wouldn’t be surprised if many people with access to hot springs would have considered using them for cooking. But finding examples isn’t so easy, so now I need your help: Are you aware of other examples of “natural sous vide”? By this I mean cooking of food at temperature below 100 °C/212 °F without the use of a temperature controlled water bath. It could be in a hot spring, near volcanoes, in steam baths or even in saunas (in a previous post on eggs I mentioned Finnish sauna eggs and Korean Maekbanseok gyeran). Any help finding other examples would be greatly appreciated! I’m interested in modern-day examples as well as traditional practices.

It’s quite amazing that two journals so relevant to gastronomy and science have gone live within little more than a month. Last month we saw the appearance of International Journal of Gastronomy and Food Science, and today the first few articles in Flavour appeared, a few days ahead of the official launch event on March 28. If you’re in London you should consider attending the seminar “Flavour and the new nordic cuisine” jointly hosted by the London Gastronomy Seminars, the Centre for the Study of the Senses and BioMed Central, the publisher of Flavour.

The articles that appeared today include a paper on umami from the Nordic food lab, a study which shows that you take smaller bites of food with a strong aroma and finally an interesting paper exploring why you often perceive taste and smell as one. Oh, one more thing – did I mention that Flavour is an Open Access journal? I suggest you check out their content section immediately!

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.

My fellow bloggers Anu Hopia (Molekyyligastronomia) and Erik Fooladi (Fooducation) together with Jenni Vartiainen and Maija Aksela have embarked on a collaboration project to explore claims about food and cooking. If you are a researcher (from any field), teacher at any level, chef or simply a foodie who finds this interesting you can find info at the end of this email on how to contact them. I bring here their description of the project in extenso:

Interdisciplinary network of culinary claims
Is it true that you mustn’t rinse, but rather brush, mushrooms? Should a steak be seared to keep the juices inside? Can you prevent fruit salad from turning brown by sprinkling it with lemon juice? Such apparently mundane questions have been source of inspiration for food geeks at least since “The Curious cook” by Harold McGee (1990) was published, but most likely much earlier. A closer analysis of such questions reveal an abundance of intriguing, surprisingly complex and unexplored questions which might be vehicles for education and even subject for research within natural and social sciences.

The world of food and cooking is full of statements on how to do things and occasionally why one should adhere to these advices. Many are rooted in tradition or are created today by us all and sometimes appear to us like modern urban stories. Some are rooted in long experience of kitchen professionals or home cooks, and some even in science. When tradition and science meet interesting things might happen. In some cases the phenomenon in question (see examples in the introduction) is well described within one field of science but is less so in another discipline, laying questions open for research. Secondly, such culinary claims, which we have termed “Kitchen stories”, provide valuable opportunities in education at various levels (see below). Thirdly, interesting questions might be revealed by laypeople, craftsmen (chefs, artisans) or even school children which in turn could end up as relevant research topics to be studied within various sciences. Finally, such kitchen stories are valuable parts of our cultural heritage and provide rich research material for scientific fields such as cultural history and sociology (see figure above).

Ongoing efforts
Thus far, we have seen several efforts toward the study of such culinary claims within food science (molecular gastronomy, MG) and since publication of Curious Cook several publications do mention such claims as part of the programme of molecular gastronomy (This, 2009; Vega & Ubbink, 2008). [1] Examples of scientific studies on culinary claims are research on beef stock cooking from the University of Copenhagen (Snitkjær et al., 2010; Snitkjær et al., 2011) and INRA Paris (This et al., 2004). Another example is whether it is a good idea (for the flavour of the dish) to separate the peel and seeds from the flesh before using tomatoes (Oruna-Concha et al., 2007). Even though some such claims have been studied within MG/food science we are not aware of studies starting from such claims within other disciplines such as ethnology, food history, sociology etc. [2] Following up one of the examples above, one might thus ask

• What claims about making beef stock do we find around the world?
• Are the various versions of one claim similar or qualitatively different?
• Do they exist in some countries/areas, being absent in others? How are they distributed geographically and in time?
• etc.

Since producing, cooking and eating/enjoying food is among the most influential phenomena throughout human history such claims should be relevant and important questions to research. Furthermore, a large proportion of such knowledge is rooted in tradition and we are thus in a hurry to collect/record it because much of it lies in the hands and minds of people only. We should not trust that our modern, globalised and urbanised society will hand down this knowledge to the coming generations in like manner as done in past times. Also, examples exist of the potential in using such claims in various levels of education. In France efforts have been carried out in schools, such as “Ateliers expérimentaux du gout” and “Programme “Dictons et plats patrimoniaux””. [3] Also we are underway, through educational research in Finland (Västinsalo & Aksela, 2011) and Norway (Fooladi, 2010), to unveil what potential this might have in science and home economics education. A collection of possible research topics/questions is given in the appendix (link to Fooducation). Our opinion is that this should be a dynamic and expanding list, adding new questions and perspectives along the way.

Prospects and invitation
We believe that this project might involve, perhaps even integrate, a manifold of disciplines as well as various research methodologies/paradigms. As shown in the figure, the phenomenon “culinary claims” forms the centrepiece, allowing the various disciplines to maintain their distinctive features, but also to let them meet in a common point of interest. Our goal is to build an international collection of kitchen stories and culinary claims to be developed and benefitted by researchers of different fields (a French collection exists [4]). We would also like to build a network for researchers, teachers, schools, practitioners and others with a common interest in this topic. Currently no funds are available, but several national applications are in. If you are interested in joining this network, let us know. At this point, we have not set any limits to who might join in, regardless of profession. Further, if you are aware of similar type of efforts, we’d be happy to learn about them.

Contact (in alphabetical order)
Anu Hopia, University of Turku, Functional Foods Forum. Professor (food development). E-mail: anu.hopia (a t) utu.fi. Web page (in Finnish): http://molekyyligastronomia.fi

Erik Fooladi, Volda University College, Norway. Associate professor (chemistry, home economics, teacher education). E-mail: ef (a t) hivolda.no. Web page: http://fooducation.org

Jenni Vartiainen, Helsinki University, Finland. Coordinator of Finland’s science education centre LUMA, PhD student. E-mail: jenni.vastinsalo (a t) helsinki.fi. Web page: www.helsinki.fi/luma/english

Dr Maija Aksela (professor), head of Finland’s Science Education Centre and the Unit of Chemistry Teacher Education, University of Helsinki. E-mail: maija.aksela (a t) helsinki.fi

Notes
[1] Some collections are available on the web, e.g. http://kitchen-myths.com and they appear to be tool to raise interest of public to natural sciences. However, many such efforts often have a rather one-sided perspective in which science carries “the truth” which is used to “debunk the fallacies of tradition”. We believe in a meeting ground for both science and tradition where both can contribute to the other on more equal terms.
[2] We do not, however, claim that such research does not exist, and would be delighted to see such research.
[3] We are not aware of whether these efforts have been followed by educational research.
[4] www.inra.fr/la_science_et_vous/apprendre_experimenter/gastronomie_moleculaire/une_banque_de_precisions_culinaires

References
Fooladi, E. (2010). “Kitchen stories” – Assertions about food and cooking as a framework for teaching argumentation. Paper presented at the XIV IOSTE Symposium, Bled, Slovenia. http://www.ioste14.org/publications/

McGee, H. (1990). The Curious Cook – Taking the lid off kitchen facts and fallacies. San Francisco: North Point Press.

Oruna-Concha, M. J., Methven, L., Blumenthal, H., Young, C., & Mottram, D. S. (2007). Differences in Glutamic Acid and 5′-ribonucleotide Contents Between Flesh and Pulp of Tomatoes and the Relationship with Umami Taste. Journal of Agricultural and Food Chemistry, 55(14), 5776-5780. doi: 10.1021/jf070791p

Snitkjær, P., Frøst, M. B., Skibsted, L. H., & Risbo, J. (2010). Flavour development during beef stock reduction. Food Chemistry, 122(3), 645-655. doi: 10.1016/j.foodchem.2010.03.025

Snitkjær, P., Risbo, J., Skibsted, L. H., Ebeler, S., Heymann, H., Harmon, K., & Frøst, M. B. (2011). Beef stock reduction with red wine – Effects of preparation method and wine characteristics. Food Chemistry, 126(1), 183-196. doi: 10.1016/j.foodchem.2010.10.096

This, H. (2009). Molecular Gastronomy, a Scientific Look at Cooking. Accounts of Chemical Research, 42(5), 575-583. doi: 10.1021/ar8002078

This, H., Meric, R., & Cazor, A. (2004). Lavoisier and Meat Stock. Comptes Rendus Chimie, 9, 1510-1515. doi: 10.1016/j.crci.2006.07.002

Vega, C., & Ubbink, J. (2008). Molecular Gastronomy: A Food Fad or Science Supporting Innovative Cuisine? Trends in Food Science & Technology, 19(7), 372-382. doi: 10.1016/j.tifs.2008.01.006

Västinsalo, J., & Aksela, M. (2011). Using kitchen stories as starting point for chemical education in high school. Paper presented at the ESERA 2011, Lyon, France. http://www.esera2011.fr/en/scientific-programme.html

A couple of books have caught my eye during the year and have naturally made their way into my Christmas wish list (and some I’ve already ordered myself). Please let me know if there are books you belive should be on this list that I have missed.

Culinary Reactions: The Everyday Chemistry of Cooking
by Simon Quellen Field
288 pages

The back cover states “When you’re cooking, you’re a chemist!”. I couldn’t agree more and figured this was a book for me. I already have my copy in front of me and see there are many interesting observations and experiments described.

Heston Blumenthal at Home
by Heston Blumenthal
408 pages

The Family Meal: Home Cooking with Ferran Adria
by Ferran Adrià
384 pages

Ferran and Heston have jumped onto the cooking-at-home-with-great-chefs waggon. They’d be more than welcome to come and cook in my kitchen, but until that happens I’ll let their books inspire me. An important thing about these books is that, given their close collaboration with scientists, I have a high expectation that the advice given in all recipes should be scientifically sound (which of course is not the case for many other cook books).

Neurogastronomy: How the Brain Creates Flavor and Why It Matters
by Gordon M. Shepherd
288 pages

I stumbled across this one by chance. It looks like a “must have” too me, and my copy is already on its way. In an interview with Salon, the author Gordon M. Shepherd, a professor of neurobiology at the Yale School of Medicine, says that:
“I began to realize that increasingly smell was for sensing the flavor of food. It goes almost unrecognized as we eat our food because we think it all comes from taste in our mouths. The more research that I did on flavor, the more I realized that the sense of smell was the dominant sense in flavor — and that we are almost totally unaware of it.”

The Oxford Companion to Beer
edited by Garrett Oliver
960 pages

Having ventured into brewing I found this book quite irresistable!

The Kitchen as Laboratory: Reflections on the Science of Food and Cooking
edited by Cesar Vega, Job Ubbink and Erik van der Linden
336 pages

I’ve mentioned this book previously. With 35 essays covering a range of topics this should be of interest to many Khymos readers!

Apart from these books we just have to face it: there’s no way around Modernist cuisine. If you don’t own a copy yet I’m quite sure it still sits there on the top of your wish list. And – if you happen to read Swedish – I would highly recommend the recently published book Matmolekyler (“Food molecules”) by Malin Sandström and Lisa Förare Winbladh (also check out their blog blog with the same name – also in Swedish).

Flavor pairing is a controversial* topic which I’ve blogged about many times in the past. In my last post I suggested that predicted aroma similarity may be a more precise term, and below is an attempt to illustrate predicted aroma similarity (of type 2d according to this classification) by using a color analogy. Let me explain a little first: The letters describe different foods and colors are used to illustrate the sum of the key odorants. The normal situation is that foods A and K (which are perceived as different because they are far apart in the alphabet) also have different colors meaning that they share few or no key odorants. A and B however are close in the alphabet and have similar colors, hence they share key odorants. In some cases foods that we think are very different (A and Z) may turn out to share several key odorants (i.e. have similar colors). The “flavor pairing hypothesis” is a way of finding the “Z” based on predict aroma similarity. I think one reason why we cannot always find the “Z” is that our sense of smell is not very analytical (compared to a gas chromatograph). One thing which I hope becomes clearer with the color analogy is that for a successful pairing one will need contrasting elements as well. This was also a general experience from the TGRWT experiments. I’m very curious whether this communicates well or just makes things even more confusing, so feel free to leave a comment below!

Let us assume that the two foods A and K with no key odorants in common taste marvelous together. Many (or possibly even most?) food pairings are of this kind.

Two similar foods A and C share a number of key odorants. This is no big surprise and most people will say that A and C are quite similar.

Aroma similarity prediction (the “flavor pairing hypothesis”) is a tool to identify Z which (surprisingly) turns out to be quite similar to A because they share key odorants. As mentioned above, finding Z is what is difficult.

Let us imagine a dish where A is a prominent ingredient. It’s combined with classic or empirical pairings (indicated with the different colors – the color tones are chose to match each other).

Based on aroma similarity prediction one can then introduce Z which (surprisingly) is similar to A because of overlapping key odorants.

One can even imagine the case where A is replaced by Z. If the process is repeated a dish can slowly morph into a new dish by exchanging one ingredient at a time.

*Controversial: See for instance the latest issue of Gastronomica where Maurits de Klepper criticizes flavor pairing under the title “Food Pairing Theory – A European Food Fad”. It’s an interesting piece and I recommend that you buy access to read it. But I should quickly add that there are a couple of things that I disagree with. What I’ve previously formulated as a flavor pairing hypothesis is turned into a theory, and I also disagree with the formulation that “the more aromatic compounds two foods have in common, the better they taste together”. In my previous blog post on the topic I have reformulated my viewpoint as follows: For foods with a predicted aroma similarity based on the analysis of it’s volatiles there is a good chance that they can be used together in a dish. It’s also a pity that de Klepper doesn’t cover the topic of key odorants (or odor activity values) properly, but mixes up the different categories (2a, 2b, 2c and 2d) of aroma similarity prediction that I’ve outlined previously. Despite this de Klepper summarizes the experiences from TGRWT very well when he says that flavor pairing “is not a guaranteed recipe for success – balancing flavors is what does the trick”. I couldn’t agree more.

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

The very first blog post on Khymos appeared on August 27th, 2006. That’s 5 years ago today – and to celebrate this the following post will be about Khymos and blogging. It’s going to be quite introvert, but hopefully you’ll appreciate the look behind the scenes! I 2006 had no clue that I would still be going on for so long. Five words that sum up the 5 years of blogging are: fun, readers, research, experiments and photography. Let me explain:

FUN: Blogging has been great fun, and I would never have continued for so long if I hadn’t enjoyed it. I’ve had a couple of long breaks, and my posting frequency varies, but that’s because of a rule I’ve put up for my blogging: No deadlines! This is to make sure the blog is driven by ethusiasm. My philosophy is that if I enjoy writing, I hope you will enjoy reading!

READERS: First and foremost blogging is fun because of you! Without readers, I wouldn’t have kept on blogging. All the feedback, comments, discussions and emails are very much appreciated, not to mention all the interesting questions and observations you send me. My only regret here is that there are questions I received months (and even more than a year ago) which I haven’t answered yet… Easy questions are often answered as quickly as possible, whereas the more difficult ones may take a little longer. But if you haven’t heard back from me in let’s say 1-2 weeks – please send a new email!

RESEARCH: Another reason it has been great fun is the opportunity it gives me to research subjects and do experiments in a more structured way. I actually learn a lot about food and chemistry while blogging. Once I’ve blogged about a topic it’s very easy to include it in presentations/lectures I give on molecular gastronomy and popular food science.

EXPERIMENTS: I really enjoy researching a subject, especially when I manage to figure out of something. In fact, few things are more rewarding than solving a problem or gaining new insight. But the great thing about chemistry is that you can do experiments as well. And with food chemistry you’re even allowed to taste!

PHOTOGRAPHY: When popularising science, and chemistry in particular, I find that illustrations and pictures are essential. As it happens I also enjoy taking pictures, so the blog lets me do a lot of things that I enjoy at the same time!

How I got started
When I first became interested in the connection between food and chemistry in the late 90′s, I searched the Internet without finding much information. I did however find some very interesting books in the faculty library, including Harold McGee’s “On Food and Cooking – The Science and Lore of the Kitchen”. Having found books about the subject, I soon started to give popular science presentations. In 2004 I was invited to attend the “International Workshop on Molecular Gastronomy” in Erice, Sicily. This was a great experience and I enjoyed meeting many of the scientists, writers and chefs involved with molcular gastronomy. When I first put up a webpage in 2002 the main purpose was to maintain a more or less comprehensive listing of books and websites with relevance to molecular gastronomy. I published it mainly as a bibliography related to my popular science lectures. After I left the University of Oslo, the page was moved to it’s present location at khymos.org. Needless to say, I’m no longer able to keep track of all the interesting things happening related to science enabled cooking, given the increasing popularity as well as the many chefs, restaurants, books, websites and interviews appearing. Therefore I’m very thankful when readers contact me about things they think I should blog about.

What do I blog about?
My blog posts mostly fall into one of the following categories:

• Announcements and recommendations of books, blogs, events, new websites etc. It’s often difficult to draw a line here, but my guiding principle here is that if I find it interesting, I hope you will as well. And of course, feel free to share news, tips and announcements with me using the contact form.
• Feature posts on a researched topic which almost always involve some cooking and experimentation, often requiring a litterature search as well. These are time consuming posts to write, but also very rewarding for myself. I wish I had more time for these!
• Travel reports such as those from EuroFoodChem, The Flemish Primitives and the MG seminars in Copenhagen allow me to practice as a journalist.
• The food blogging event They Go Really Well Together (TGRWT) allowed me as well as all the participants to explore food pairings based on shared impact odorants.
• The occasional interview satisfies my thirst for learning more from knowledgeable people I admire. I should do more interviews!
• Book reviews is something I’ve only just begun doing. Time consuming, but also rewarding.

A category which I haven’t dug properly into yet is recipes for conventional food accompanied by scientific explanations. This has been pioneered by Hervé This in Révélations gastronomiques (available in German but not in English), and I love the format that answers all the whys right there in the middle of the recipe. I hope I will find time for such blog posts in the future!

The current blog
After a complete makeover of the blog in January 2009 I decided to move the static content from the old Khymos site to the blog. Some changes have been made, so for those of you who regularily read Khymos feed through an RSS reader or a news aggregator, I suggest that you visit the website to check out what the complete site looks like now.

Since the facelift in January 2009 there are a couple of notable changes to help you navigate around the site. These include a tag cloud, a list of popular posts and a list of the last comments (all shown in the picture below). There is also a search field providing a full text search of the entire contents of Khymos. One of the technical advantages of a blog over a conventional website is of course the RSS funtion which allows posts to be aggregated and served to readers in their favorite RSS reader. If you’re not familiar with this, try pressing the large orange icon in the upper right corner and see what happens! Most web browser today include a basic RSS reader. For those who prefer email there is also a possibility to subscribe to blog posts via email.

If you only read the RSS you miss a number of features available on the webiste.

Most popular posts and pages
The most viewed posts and pages from April 2008 – August 2011 are (total number of views in this time period):

Top 15 blog posts
Towards the perfect soft boiled egg (90,185)
Perfect steak with DIY “sous vide” cooking (43,986)
First experiments with sodium alginate (34,698)
A mathematician cooks sous vide (19,156)
Edible cocktails with gelatin (18,304)
A pinch of salt for your coffee, Sir? (15,299)
Hydrocolloid recipe collection (13,184)
Speeding up the Maillard reaction (12,233)
No-knead bread (9,227)
TGRWT #10: Pizza with blue cheese and pineapple (8,994)
TGIF: Fed up with foam? (8,805)
TGIF: Periodic tables of food (8,180)
Glutamic acid in tomatoes and parmesan (7,696)
Ice cubes and air bubbles (7,477)
Coffee espuma with garlic and chocolate (TGRWT #1) (7,336)

Top 10 pages
Recipe collection (120,066)
TGRWT (25,916)
Flavor pairing (20,389)
Molecular gastronomy (15,949)
Suppliers (13,476)
About Khymos (13,041)
Articles (12,080)
People (7,862)
Videos (7,084)
Reference & technique (6,010)

Blog posts I enjoyed writing
Looking at the list above suggests that my philosophy about you enjoying reading what I enjoy writing doesn’t always hold true. Some of the posts that I really enjoyed researching and writing do not show up on the lists above. Here’s my secret insiders guide to the best hidden posts of Khymos that do not show up in the lists above:

The series on Ten tips for practical molecular gastronomy
The serices on Wonders of extraction: water, oil, ethanol, espresso, pressure
Nocino walnut liqueur part I and part II
The follow up posts on egg yolks: Perfect egg yolks, Perfect egg yolks part 2
Norwegian egg coffee
DIY mineral water (including an Excel spreadsheet)
Soda fountain science explained
Interview with Chris Young (co-author of Modernist Cuisine!)

Some statistics
So far I’ve written 270 blog posts, including the one you are reading now. The blog posts are grouped in 24 categories and have been tagged with 1033 different tags. Comments are moderated, the major reason for this being spam. The Akismet spam killer has so far caught ~445,000 spam comments since I turned it on. Compare that with the 2207 comments that have been approved and I think you see why comment moderation is necessary (although a side effect is that legitimate comments are being held back for approval, thereby delaying the discussion in the comment threads).

A grand total of 2.9 terabytes have been served during these 5 years according to the logs of the company hosting Khymos. This amount of traffic is the result from 8.5 million visits resulting in 78 million hits, requesting 61 million files and 30 million pages in total. But one can only wonder what kind of traffic numbers all the spam comments generate… More numbers from the logs can be found in the table below.

Webmetrics is tricky, and simply counting hits or views may not tell the whole truth. One company which specialises in web metrics is Quantcast. Their monthly visitor count for Khymos is shown below:

More detailed data is available directly on Quantcast’s page about Khymos.

The number of RSS subscribers in Google Reader has been growing steadily and a couple of weeks ago it was around 3500. But then something happened – I don’t know what – and the number is now approaching 40000. The strange thing however is that this increase in subscribers is not reflected in the other statistics, so it’s hard to really tell whether it’s a realistic number or not.

Blogging software
I can still remember how I started reading about different blogging platforms available in 2006. I ended up chosing WordPress which at that time had reached v.2. Today I’m so happy that I chose WordPress! I’m amazed by the development team and what they have achieved, and at this point I should really forward a big thank you to the team behind WordPress. During these five years the software has really matured and it’s a great tool for any blogger – hereby highly recommended (and did I mention that it’s free?).

More about photography
Some of the very first pictures on the blog were shot with a Canon Powershot A400, a simple point & shoot camera that left a lot to be desired in handling. With enough light however the camera takes decent pictures, and the 3MP sensor serves as a good reminder that when having pictures printed in the typical 10 x 13/15 cm size you really don’t need more pixels. In 2007 it was time to upgrade to a Ricoh GX100 – I got this camera after long considerations, and what appealed to me was the combination of a real wide angle zoom (equivalent to 24-70 mm) and full manual controls. The downside is perhaps that the camera is a bit slow, and the low light capabilities are also limited. And then in 2010 I finally stepped up and got myself a DSLR. I considered both D90 and D700 from Nikon, as well as the 7D and 5D mark II from Canon, but in the end I landed at Nikon D300s. The controls and handling are excellent, and the camera is fast – it actually takes the picture when you press the button, not a second or so later as is the case with many P&S cameras. In combination with the my prime lenses Nikkor 35 mm 1:2 and 20 mm 1:2.8 (which I bougt used) I’m well off in most low light situations. Both have excellent close ranges, and with the narrow depth of field they are excellent companions for food photography. And if needed I could always use the macro function on GX100 if needed.