My immersion circulator is working again! And the first thing I decided to do was to cook eggs at 63.0 °C for 40, 60, 75, 110 and 155 min and show you the results. If you read my last blog post on Perfect egg yolks or have stumbled across the paper Culinary Biophysics: on the Nature of the 6X°C Egg you may recognize that these times correspond to egg yolks with textures similar to sweetened condensed milk, mayonnaise, honey, cookie icing and Marmite respectively. I used the iso-viscosity graph from the paper mentioned to determine the cooking times as shown below.

The figure shows how cooking times at 63.0 °C are determined to achieve different textures. (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.)

As the individual eggs reached their cooking times they were held in cold water until the last egg was finished. I then cracked all the eggs and took the pictures below to illustrate the differences in textures. I think the picture speaks for itself. The amazing thing is that the only difference between the eggs is the cooking time!

It can be difficult to judge textures properly from still photos, so I also shot a few video clips to illustrate the texture of the 40, 75 and 155 min eggs (by the time I shot the videos the yolks had become more viscous, possibly due to cooling and/or evaporation). The texture ofthe 155 min egg yolk was perhaps the most fascinating with a tremendous plasticity. There must be some exciting culinary uses for this!

If an egg is to be served by itself one will typically also want to set the white. There was a question about this to my previous post, and a reader even tried with 2 min pre- or post-boil. Without cooling the difference between pre- and post-boil was quite significant as evidenced from the pictures. I did a similar experiment but cooked the eggs at 63.0 °C and opted for a 3 min pre- or post-boil with the small difference that I cooled the egg back to room temperature after/prior to the pre-/post-boil to avoid any interference between the 63 °C and 100 °C treatments. This worked very well and I wasn’t able to detect any difference between the pre- and post-boiled eggs.

It doesn’t matter if you pre- or post-boil your egg as long as you cool it to room temperature inbetween the boiling water and the temperature controlled water bath.

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

An updated version of “Texture – A hydrocolloid recipe collection” is now available for download (version 2.3). The longer I work on this, the more I realize that it will never really “finish” – there’s always more to add. And believe me – my todo list is still quite long (and I even have some feedback which I haven’t had time to incorporate yet). But I thought that since it’s more than a year since the last update, it was about time to share with you the things that have been changed. Major changes and updates include:

Pictures: This is the biggest visual change! Some recipes are now equipped with pictures which may give you an idea of the texture AND they indicate that the recipe has indeed been tested. But I need your help to add more pictures to the recipe collection (please follow the link to read more about how you can contribute pictures)! And of course - a big thanks to those of you who have already contributed your pictures!

Recipes: Recipes have been added and the total number is about 310 now. I’m getting a little more picky now with regards to which recipes I add. Ideally each new recipe added now should illustrate something new.

I should mention that I’m very grateful for feedback from readers and users of this recipe collection. Thank you very much with helping me improve the document! If you find typos, wish to comment on something or have suggestions on how to improve the collection, please do not hesitate to write me an email at webmaster (at) khymos (.) org or just write a comment in the field below.

Please head over to the download page for the links.

A picture is worth a thousand words, and this is also true for recipes. Several of you who have downloaded “Texture – A hydrocolloid recipe collection” have asked for pictures and now it’s time to do something about that! A picture can illustrate texture well and is an excellent supplement to the descriptions. I therefore invite to you to contribute to the recipe collection by taking pictures to accompany the recipes. But before you run to grab your camera, please take a note of the following:

• Pictures should clearly show the component described in the recipe. If you take a close up picture against a neutral background it’s good if one still has a feeling of what the scale is.
• Only send a picture if you actually followed the recipe! This way the picture can also serve as an indication that the recipe as been tested. However, if you for some reason have modified a recipe for a better or different result I would also be very interested in hearing about this.
• Pictures should be in focus and well lit. But remember that Photoshop can do wonders, so please do send pictures even though the colors seem a little dull.
• Pictures will be cropped to a 1:1 aspect ratio as shown above
• Preferred minimum resolution is 450 x 450 pixels
• It’s a requirement that the picture is taken by you and that you are willing to provide it for use in “Texture – A hydrocolloid recipe collection” under a Creative Commons Attribution – Noncommercial-Share Alike 3.0 Unported License since the whole recipe collection is published under such a license
• I reserve the right to crop pictures and do color/brightness/sharpness adjustments
• I reserve the right not to use pictures received (and I only intend to include one picture for every recipe)
• Pictures will be attributed to the photographer as shown in the above illustration.

If you have read the above and agree you’re ready to send your texture pictures to me at this email address: texture.pictures (at) gmail.com. Remember to include the name of the recipe photographed and your name as it should appear under the picture. Thank you very much for helping me make this collection even more useful

Just a small reminder that the deadline for the current round of TGRWT #17 is a little later than usual: May 8th. I took the picture above for last month’s TGRWT (where it was combined with chicken) and came to think that it actually qualifies for this month’s TGRWT as well. It’s rose foam on a spoon with apple, celery and almonds, and the foam is sprinkled with a little pepper.

As an experiment I tried to freeze the leftover rose foam and was quite surprised by the resulting texture. It was easy to scoop due to the incorporated air and had a nice mouth feel. There were no ice crystals and the texture was almost a little chewy. What would one call this? Ice cream? Sorbet? No – there is no cream and the texture is much lighter. Frozen sorbet? Foamed sorbet? Frozen foam? Any suggestions? I think I’ll make a variation of the frozen foam for TGRWT #17

Frozen rose foam

Frozen rose foam is easily scooped due to all the air bubbles

For this month’s “They go really well together” event (TGRWT #16) hosted by Supernova Condensate I decided to leave the chicken untouched and focus on the rose component. I had long wanted to try Chad’s Lemon whip (which I’ve included in Texture) where lemon juice is thickened with xanthan and then whipped to a thick foam after addition of methyl cellulose. I started with water, a little sugar and about 10 g of rose water. Having added xanthan and methyl cellulose I tasted it and decided to double the amount of rose water, add some more sugar and add a little lemon juice for acidity. I can imagine that rose water comes in differents strengths so it’s advisable not to add all from the start.

Rose foam
15 g sugar
0.7 g xanthan (0.49%)
100 g water
20 g rose water
8 g lemon juice
1.2 g methyl cellulose (0.84%)
(I used Metil from Texturas)

Grind sugar and xanthan. Sprinkle into water, rose water and lemon juice with hand mixer on full speed. When the xanthan is dispersed add methyl cellulose a little by little with the mixer still on. Mix for another 5-10 minutes until bubbles are small and uniform and the foam is dense and stable. If desired the foam can be whipped with an iSi whipper charged with nitrous oxide. I served the rose foam with diced apples, stalk celery and chopped almonds as a side dish to roasted chicken. Mashed potatoes with basil leaves, topped with a good olive oil and ground pepper was nice with the chicken.

Verdict: The rose foam is thick and lucious. The rose aroma blends very well with apple aroma. Lemon, almonds and celery give a nice contrast. The overall combo was a pleasant surprise! My previous encounters with rose water have been somewhat overpowering (especially in food from the Middle East), but the rose foam was much milder as I had diluted it with plenty of water.

The foam is stable on the time scale of minutes to hours. When left overnight the bubbles coalescese, but the volume of the foam remains more or less the same. Foam from the previous day can easily be whipped up again with a hand mixer.

Newly whipped rose foam (left), 18 hours later the bubbles have coalescesed (right). I apologize for the somewhat weird colors.

An updated version of “Texture – A hydrocolloid recipe collection” is now available for download (version 2.2). There are two file sizes available: screen resolution (~1 MB) and high resolution for printing (~5 MB). Some recipes have been added bringing the total number up to about 270 recipes. Apart from this the version includes corrections of typos and updates of indexes and the supplier list. There is a new index for alcoholic preparations plus a small glossary. Again I should mention that I’m very grateful for feedback from readers and users of this recipe collection. Thank you very much with helping me improve the document! If you find typos, wish to comment on something or have suggestions on how to improve the collection, please do not hesitate to write me an email at webmaster (at) khymos (.) org or just write a comment in the field below.

The suggested temperature range for the roast beef was from 60 °C for a pink interior to 68 °C for grey meat. I settled on 63 °C. I was a little optimistic regarding the timing, so when our guests had arrived and I checked the meat (after 1h 30m) the core had only reached 53 °C. First lesson learnt: meat is a poor heat conductor. I quickly figured that my guests would become very hungry if I were to wait for the core temperature to reach that of the water bath. I therefore turned the water bath up to 68 °C, and put the meat back into the water bath – this time in a normal plastic bag and with a temperature probe at the core. This worked surprisingly well, the pressure of the water pushing out all the air. After another 45 min it had reached 62 °C and I removed the meat from the water bath, saved the juices for the gravy, rubbed the meat with salt and pepper and gave it a quick pan sear with plenty of butter. Despite my bad timing the beef came out extremely moist and tender – I dare say that I have never before achieved such a result with a roast beef in my kitchen! And being my first attempemt at sous-vide with my immersion circulator it was extremely satisfying.

Today I prepared the chicken breast, and I figured that 1h 30m should be sufficient for 700 g of meat. The chicken came out very nice as I served it with fresh pasta, a curry sauce and some salad. Again the meat was moist and tender – and so different from most of the chicken I’ve prepared both at home and been served at restaurants.

I should also mention that I made 68 °C eggs this morning. I left them in the water for 1h. The egg white was very soft – almost runny – whereas the yolk had set but was still very pliable. Comparing this with the eggs over at Fooducation it’s clear that even with constant temperature time does play a role. My 1h @ 68 °C eggs had a white that looked more or less like the white of Erik Fooladi’s 6h @ 65 °C eggs. The are probably several reasons for this, but I guess that the kinetics of protein coagulation are mcuh more complex that one might expect at first. But that’s a different story.

Several comments to my last post asked about pricing and where to buy immersion circulators. Basicallyl any laboratory supplier sells these. And even the simplest models have temperature stability of +/- 0.1 °C or less. Amazon also has a couple of models available from Fischer/Thermo Scientific ranging from around $900-2000.

Texture – A hydrocolloid recipe collection
It’s a pleasure for me to announce that an updated version of the hydrocolloid recipe collection is available for free download as a pdf file (73 pages, 1.8 Mb).

What’s new?
Several new recipes have been added (now counting more than 220 in total), including recipes with cornstarch, guar gum, gum arabic, konjac and locust bean gum. All in all 14 different hydrocolloids are included (plus lecithin which technically isn’t a hydrocolloid). In each section recipes are now sorted according to the amount of hydrocolloid used. The appendix has been updated with tables for comparison of hydrocolloid properties, hydrocolloid densities and synergies. The perhaps biggest change is that all recipes have been indexed according both to the texture/appearance of the resulting dish and according to the hydrocolloid used. Let’s say you want to make spheres, this index will show you which hydrocolloids can be used (that’s right – there are other possiblities than sodium alginate) and list the example recipes.

Foreword
A hydrocolloid can simply be defined as a substance that forms a gel in contact with water. Such substances include both polysaccharides and proteins which are capable of one or more of the following: thickening and gelling aqueous solutions, stabilizing foams, emulsions and dispersions and preventing crystallization of saturated water or sugar solutions.

In the recent years there has been a tremendous interest in molecular gastronomy. Part of this interest has been directed towards the “new” hydrocolloids. The term “new” includes hydrocolloids such as gellan and xanthan which are a result of relatively recent research, but also hydrocolloids such as agar which has been unknown in western cooking, but used in Asia for decades. One fortunate consequence of the increased interest in molecular gastronomy and hydrocolloids is that hydrocolloids that were previously only available to the food industry have become available in small quantities at a reasonable price. A less fortunate consequence however is that many have come to regard molecular gastronomy as synonymous with the use of hydrocolloids to prepare foams and spheres. I should therefore emphasize that molecular gastronomy is not limited to the use of hydrocolloids and that it is not the intention of this collection of recipes to define molecular gastronomy.

Along with the increased interest in hydrocolloids for texture modification there is a growing scepticism to using “chemicals” in the kitchen. Many have come to view hydrocolloids as unnatural and even unhealthy ingredients. It should therefore be stressed that the hydrocolloids described in this collection are all of biological origin. All have been purified, some have been processed, but nevertheless the raw material used is of either marine, plant, animal or microbial origin. Furthermore hydrocolloids can contribute significantly to the public health as they allow the reduction of fat and/or sugar content without loosing the desired mouth feel. The hydrocolloids themselves have a low calorific value and are generally used at very low concentrations.

One major challenge (at least for an amateur cook) is to find recipes and directions to utilize the “new” hydrocolloids. When purchasing hydrocolloids, typically only a few recipes are included. Personally I like to browse several recipes to get an idea of the different possibilities when cooking. Therefore I have collected a number of recipes which utilize hydrocolloids ranging from agar to xanthan. In addition to these some recipes with lecithin (not technically a hydrocolloid) have been included. Recipes for foams that do not call for addition of hydrocolloids have also been included for completeness. Some cornstarch recipes have been included to illustrate it’s properties at different consentrations. Recipes where flour is the only hydrocolloid do not fall within the scope of this collection as these are sufficiently covered by other cook books.

All recipes have been changed to SI units which are the ones preferred by the scientific community (and hopefully soon by the cooks as well). In doing so there is always uncertainty related to the conversion of volume to weight, especially powders. As far as possible, brand names have been replaced by generic names. Almost all recipes have been edited and some have been shortened significantly. To allow easy comparison of recipes the amount of hydrocolloid used is also shown as mass percentages and the recipes are ranked in an ascending order. In some recipes, obvious mistakes have been corrected. But unfortunately, the recipes have not been tested, so there is no guarantee that they actually work as intended and that the directions are complete, accurate and correct. It appears as if some of the recipes are not optimized with regard to proper dispersion and hydration of the hydrocolloids which again will influence the amount of hydrocolloid used. It is therefore advisable to always consult other similar recipes or the table with the hydrocolloid properties. The recipes have been collected from various printed and electronic sources and every attempt has been made to give the source of the recipes.

Since recipes can neither be patented nor copyrighted, every reader should feel free to download, print, use, modify, and further develop the recipes contained in this compilation. The latest version will be available for download from the static Khymos site and will also be announced here. I would like to thank readers for giving me feedback and suggestions on how to improve the collection. Feedback, comments, corrections and new recipes are always welcome at webmaster (a t) khymos ( dot ) org.

Just wanted to point you to a beautiful picture gallery of edible cocktails accompanying an article by Betty Hallock at LA Times, “Cocktails you can eat”.

The recipes (shortened and converted to metric units by me) are as follows:

Blueberry martini jelly shots
300 mL vodka (blueberry flavored)
60 mL simple syrup
25 g gelatin (6.9%)
35 fresh blueberries

Mix vodka and syrup in small saucepan. Add gelatin and leave for 5-10 min until soft. Gently heat saucepan and stir until gelatin dissolves (approx. 10 min). Strain to remove any undissolved gelatin. Place bluberry in cocktail mold and pour vodka mixture into each mold. Cool until set. Makes about 35 cocktails of 15 mL each. (Adapted from Bar Nineteen 12)

Prosecco gelée
1 length of a vanilla bean
140 g sugar
15 g gelatin sheets, bloomed (3.1%)
340 mL Prosecco (or other white wine)

Scrape seeds from vanilla bean and mix thoroughly with sugar. Mix water and sugar in saucepan and heat over high heat until syrup almost comes to a boil. Remove from heat and bloomed gelatin and stir until it dissolves. Add wine and stir gently. Pour into 20 x 20 cm pan lined with plastic wrap and cool until set. Cut into squares, turn upside down to display settled vanilla beans and serve. (Adapted from Craft pastry chef Catherine Schimenti)

B-52 jelly shots
170 mL Kahlúa
170 mL Baileys
170 mL Grand Marnier
24 g gelatin sheets (4.7%)

Place each liqueur in separate bowls and add 8 g gelatin to each. Cover and leave until gelatin has softened. Pour Kahlúa/gelatin into a saucepan and heat over low heat until gelatin dissolves. Strain to remove any remaining solids. Pour liquid into a 10 x 20 cm pan lined with plastic wrap. Cool for about one hour. Repeat with Baileys, and then with Grand Marnier, pouring the newly prepared liqueur on top of the set liqueur in the mold. Cut into pieces and serve. (Adapted from Bar Nineteen 12)

Gin and tonic gelée
170 mL gin
10 g gelatin (2.2%)
280 mL tonic water
finely grated zest of 4 to 5 limes
1 T citric acid
1 1/2 t baking soda
1 T powdered sugar

Let the gelatin soften in gin for 5-10 min. Heat over low heat and stir until gelatin has dissolved. Pour in tonic water carefully (to avoid it from bubbling over), swirl the contents to obtain a homogeneous mixture and immediatly pour contents into 40 mL molds. Cool. To serve, unmold the gelée and sprinkle each cocktail with lime zest and a little of the premixed citric acid, baking soda and powdered sugar. Serve immediately. (Adapted from Providence pastry chef Adrian Vasquez) For reference, you might want to compare this recipe with Eben Freeman’s Jellied G&T.

You might notice that the amount of gelatin varies over a pretty large range from 2.2-6.9%. This is also well above the typical concentration found in jellies (0.6-1%). A possible reason for the large range would be that alcohol interferes with the setting of gelatin, and a quick plot of gelatin vs. alcohol content suggests that this might be the case.

But as you can see from the B-52 jelly shots, the same concentration of gelatin is used for Baileys (17% alcohol), Kahlúa (26.5% alcohol) and Grand Marnier (40% alcohol), so there should be some room for variation here (I doubt that the resulting variation in texture was actually intended in this recipe). So if we round off, the linear regression yields the following correlation between gelatin and alcohol:

% gelatin to add = (% alcohol in final mix x 0.1) + 2

One thing that surprises me is that none of the recipes call for gellan? This hydrocolloid is said to have superior flavor release properties as it is more prone to break once you chew it. From what I know, it should work fine with alcoholic beverages. Has anyone tried this yet?