As I mentioned in the post about the exciting color chemistry of nocino I picked some unripe walnuts last year in August when visiting family in Germany. These walnuts were in fact a little to ripe to make nocino from. Preferably the walnuts should be picked end of June when you can still push a knitting pin through the center. Mine were stone hard, but I decided to give it a try anyway, and it shure was worth the bottle of vodka! I checked a couple of recipes and found that many use cinnamon and cloves together with lemon (with peel). I figured I also wanted to try star anise and proceeded with two batches.

Nocino extracted with 45% ethanol
For extraction (> 3 months)
529 g unripe walnuts
385 g 60% ethanol
140 g water

Spices and sugar
4.0 g cinnamon stick
1.2 g star anis
1.2 g cloves
12 g lemon wedge
100 g sugar

Nocino extracted with 60% ethanol
For extraction (> 3 months)
481 g unripe walnuts
436 g 60% ethanol

Spices and sugar
0.8 g star anis
7.8 g cinnamon
12 g lemon wedge
100 g sugar

I covered the walnuts with alcohol in August last year and let them rest for almost 8 months (you can probably do with less, especially if you quarter the walnuts). I then removed the walnuts and added spices, lemon and sugar. After two days I removed the lemon wedge and approximately one month later I filtered off all the spices. As you can see from the pictures below the filter easily clogged. Using normal coffee filters I had to change them roughtly 4-5 times for each batch. I let the filtered nocino rest for some more weeks and then carefully decanted it into a glass bottle, leaving the newly set residue behind. If desired the nocinos can be diluted with water and/or vodka.

Precipitation in nocino extracted with 60% ethanol shown (upper left), filtering was slow (upper right) due to extensive clogging (lower left). A black film had also formed on the inside of the glass.

Nocino tastes marvellous, despite the motor oil like appearance during steeping! The difference between the two ethanol concentrations was less than I had expected. There was significantly more precipitation of black particles with the higher ethanol concentration. Both were however very drinkable! The only thing I might change the next time I attempt this is the amount of spices. I felt that the spices were perhaps a little too dominant and overpowered the walnut flavor, but the flavor was nice anyhow. Since I used walnuts that were a little too ripe it might be that less flavor was extracted, so I assume that my nocino is weaker compared to nocino made with the proper unripe walnuts. This might as well explain why the spices were a little too pronounced.

Update: Reading Elise’s comment below I realized that there was one thing I forgot to mention. Since the walnuts were picked late I could neither cut them in half nor pierce them. After extraction I tried to cut a little into the soft shell under which the black walnut shell is barely visible.

I’ve seen a recommendation to try nocino with strong cheese whereas others prefer it over vanilla ice cream. I’ve also come across two recipes for nocino ice cream so it’s a quite versatile liqueur!

Inspired by the Swedish bread blog Pain de Martin which I recently discovered I decided it was time to have a go at sourdough breads! Although one of my favorite types of bread it’s a long time since I gave it a try and even longer since I actually succeeded. Leaving apple peel covered with water for two weeks in a cool place (15 °C) I got a light apple cider which I used to make a starter some years ago. I followed a recipe from the Norwegian artisan bakery Åpent bakeri and it gave a marvelous bread. But since then I’ve tried to repeat this twice without success. No wonder that even Rose Levy Beranbaum in her book “The Bread Bible” writes that she didn’t intend to include a chapter on sourdough at all. There’s no doubt that sourdoughs are tricky, but I was a litte surprised and disappointed that someone who sets of to write a 600+ page book on bread even considered to skip sourdough… Luckily she changed her mind and the introduction has a fascinating nice-to-know fact: 1 g flour contains about 320 lactic acid bacteria and 13000 yeast cells!

I believe one the reasons why sourdoughs seem to live their own lifes sometimes is that they need to be kept in a warm place. My kitchen isn’t that warm so I figured it was time to use my immersion circulator and give sourdough another chance (who says you can only use immersion circulators for sous vide anyway? - I think my next project will be to make yoghurt!). With a thermostated water bath keeping a sourdough starter at constant temperature is as easy as 1-2-3. But surprisingly I haven’t seen any blogposts yet from people using their sous vide water baths for sourdough starters (although some have built their own water baths for this purpose using aquarium equipment).


Fresh apple peel in water. This particular experiment failed - the cider smelled OK, but there was quite a lot of mould on the surface after two weeks so I didn’t dare to proceed …

It was Martin’s post on an apricot starter that triggered my desire for sourdough (but careful - never close your jar with a rubber as shown in his picture!). I got a bag of dried apricots and gave it a try. There was some bubbling and it smelled quite nice, but the bread dough never rose properly. I later found out that in a comment to the first post and a later post on the same topic it was pointed out that the apricots should not be treated with sulfur dioxide or a sulfite (used to conserve the fruit, appears on labels as E220-228 in Europe). That’s very obvious once you think about it, because the sulfur dioxide/sulfite is there to kill microogranisms and increase shelf life. For a sourdough however you want living microorganisms! The solution to this is to use untreated dried apricots. I haven’t been able to find any yet, but I’ll definitely give it a new try once I find some! Other options of course are to use dried or fresh apples, pears, grapes - preferably not treated with pesticides or sulfur dioxide - as the surface of these fruits are host to many yeasts.

A relatively firm rye starter with 150 g water and 200 g whole grain rye flour (left) shows signs of yeast activity after 24h at 28 °C (right).

Having failed with the apricot starter I decided to give a traditional rye sourdough a try, using a recipe from the book “Brød” (=bread) by “Åpent bakeri”. I got a nice bubbling after 1 day, but the starter was pretty dry. As I discarded a portion and fed more flour and water to the starter it seemd as if it died… I (believe) I followed the recipe very accurately (except for the very first day where I opted for a hydration of 75% instead of 60%), but the final dough never rose, so I had to cheat and add bakers yeast in order to actually get the breads baked. Acid production was fine however and the resulting flavor was very delicious and I got the crumb that I desired! However, with all these problems I figured it was time to turn to the scientific litterature and read more on sourdouhs … More on what I found out in a follow up post.

One last thing: Despite my limited experience with sourdoughs I’ve already been a little annoyed by recipes for starters that require one to discard a significant portion of the sourdough every day before feeding the start with more water and flour. One obvious way around would be to start at a much smaller scale so that every feeding can be done without having to waste any sourdough. In fact Kurt Janz already has a post with detailed instructions on a less wasteful sourdough (and he BTW has one of the most comprehensive sites on sourdough I’m aware of including a sourdough calculator). The only reason I could think of why one perhaps would want to use more than a couple grams of flour to start with would be to outnumber any unwanted yeasts or bacteria from the air or the equipment. Is this the case? Are there any other reasons? To circumvent this one would simple have to work very clean and wash all equipment properly.

Just a quick note to point you to the new blog “Cooking issues” featuring Dave Arnold and Nils Norén from the French Culinary Institute. In addition to posts inspired by ongoing activities at the FCI they have a comprehensive primer on the use of rotavaps in the kitchen (including several recipe suggestions!). Highly recommended!

Last year, while visiting family in Germany, I decided to pick some walnuts to bring home to Norway. They were not ripe, which was good, because I was planning to make nocino, a walnut liqueur. You can easily find a number of recipes by googling and there is also a nocino-thread over at eGullet.

What fascinated me the first time a saw nocino mentioned in a book about liqueurs was the nearly black color. Many recipes comment that after steeping, the liquid looks more like used motor oil than something edible. The color is really amazing and I also observed that most recipes recommended the use of gloves as the stains from the unripe walnuts would not easily come off. The juice from the walnuts is a light yellow green color to start with, but when exposed to air it quickly turns dark brown. Color chemistry is always fascinating and I couldn’t resist the temptation to investigate this further.

This picture was taken only 3 days after I steeped the walnuts in ethanol.

I did a little research and found a number of scientific papers about nocino. Some of them focus on the high content of phenolic compounds and possible health effects. Personally I can’t really see how nocino will ever become a significant source of phenolics in anyones diet. Even the article entitled “Influence of processing variables on some characteristics of nocino liqueur” is mainly concerned with how the process variables affect the antioxidant activity. There is no mention of taste or aroma (and this is perhaps why I would not classify these papers as molecular gastronomy), but the authors conlcude that walnuts picked earlier (more unripe) combined with a long steeping time (3 months) give a higher content of phenolics. They correlate the phenolic content to a measure of firmness, but for those making nocino at home an easy way to test the walnuts is to pierce them with a knitting pin - the walnut should be soft all the way through. As a side note I should mention that the walnuts I used were picked in August which is way too late - the inner walnut shell was stone hard, but I decided to give it a try anyway (more on how it all worked out in a comming follow-up post). The closest I came to some input regarding aroma was an article were 12 different phenolic compounds were analyzed in walnut extracts made with 40, 60 and 96% ethanol. Although the total phenolic content was highest when using 96% ethanol, they found that the concentration of some phenolics (protocatechuic, sinapic and p-coumaric acid) increased with the concentration of the ethanol used for extraction, whereas other phenolics (gallic, chlorogenic, vanillic and syringic acid, (+)-catechin, juglone) were best extracted with 40% ethanol. Polyphenolic compounds are normally bitter or astringent. The low molecular weight compounds are typically more bitter. With increasing molecular weight bitterness decreases whereas astringency generally increases. The solubility in water decreases with higher molecular weight. As I mentioned in a previous post on ethanol extractions this is the reason why 30-60% ethanol is most commonly used for infusions and extractions.

Even though the contents of the jar seems to be black, it’s actually still a bright green color if you shine enough light through it. The reason for this is that the jar was kept well closed. Once the nocino is filtered and thereby exposed to plenty of air the color will change to dark orange brown.

Despite all the papers on nocino I still didn’t know more about the colors of nocino, and what I was really searching for was an account of the color changes I observed. The incredible staining of skin and the change from bright green to dark brown and nearly black upon contact with air. Back in 1856 Reischauer and Vogel [1] studied and isolated a compound they named juglone after the latin name of walnut (juglans). In 1885 the structure was elucidated by Bernthsen and Semper who two years later also synthesized the compound [2]. Later Mylius [3] isolated a precursor to juglone, α-hydrojuglone, which upon oxidation yields juglone. And in 1950 Daglish [4] showed that what had become known as “apparent vitamin C” was in fact a hydrojuglone glucoside, a precursor to α-hydrojuglone. This is a nice illustration of how the most stable molecules are discovered first, before one realizes that there are more reactive precursors.

It’s also interesting to note that the structure of juglone is closely related to lawsone, a compound found in the henna plant (Lawsonia inermis) which is used for skin coloring. The hydroxyl group on the quinoid double bond causes lawsone to easily undergo oxidative dimerization (which I belive leads to compounds with a darker color - this would explain why henna color typically needs some time to develop). In the henna plant lawsone exists as a glucoside, and I would suspect that it is in the form of hydrolawsone glucoside which looses glucose and is oxidized as is the case with hydrojuglone.

Read on: Nocino - walnut liqueur (part II) - includes recipes!

References:
[1] Vogel, Reischauer Jahresberichte 1856, 693.
[2] Bernthsen, Semper Berichte der Deutschen Chemischen Gesellschaft, 1885, 18, 203. Bernthsen, Semper Berichte der Deutschen Chemischen Gesellschaft, 1887, 20, 934.
[3] Mylius, F. Berichte der Deutschen Chemischen Gesellschaft 1885, 17, 2411. Mylius, F. Berichte der Deutschen Chemischen Gesellschaft 1885, 18, 463.
[4] Daglish C. Biochem J. 1950, 47, 452. Daglish C. Biochem J. 1950, 47, 458. Daglish C. Biochem J. 1950, 47, 462.

As I mentioned in the previous post I put the leftover rose froam from TGRWT #16 in the freezer and was surprised by the result. Inspired by this I thought I would extend this and substitute apple juice for water for TGRWT #17. As apple juice is quite sweet I started off with 20 g sugar, but once frozen it lacked sweetness and even was a litte icy, so I upped the amount to 40 g. The picture above may suggest that the foam could be served for dessert, but read the verdict before you make huge amounts of the foam.

Frozen rosy apple foam
2.1 g xanthan (0.50%)
3.6 g methyl cellulose (0.85%)
40 g sugar
6.5 g rose water
300 g apple juice
70 g lemon juice

Grind xanthan, methyl cellulose and sugar in mortar (easier dispersion of hydrocolloid in water). Mix liquids in a bowl and disperse sugar and hydrocolloids into solution with a hand held immersion blender. For better foam production change to tilted disk attachmend or use an electric whisk. Freeze.

Verdict: Aroma wise I was quite satisfied and even my wife liked it. The rose flavor was pronounced but not overwhelming and balanced nicely with the apple. I had to use quite a lot of lemon juice though to get it acidic enough for my taste. The texture was not as smooth as I had hoped for however. It was a little icy and even brittle when scooped and certainly need improvement if I’m to make this again. Another disappointment was the aftertaste - it was actually not good at all. I suspect that it’s one of the hydrocolloids. Anyone have similar experiences? As it is now I would not serve the frozen foam as a dessert because of the aftertaste. But it could work well as an element in a dish. And I was thinking if adding a little fat, for instance as cream, could help both the texture and remedy the aftertaste?

I only used my new Bamix for dispersion and whipping this time. First with the knife attachment for dispersion (top left) and then with the tilted disk for whipping (top right). Compared with the rose foam I made for TGRWT #16 using a conventional hand mixer the bubble size was more non-uniform when using the Bamix (bottom left). The foam scoops nicely when frozen, but texture leaves a little to desire (bottom right).

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

One of the more curious cookbooks I own is a German one entitled “Kochen und Backen nach Grundrezepten” (Cooking and Baking with Base recipes). It was first written in 1932 and has been updated regularily ever since. Each section typically has a standard recipe which indicates the ratios to use followed by suggested variations (just like The improvisational cook). It also has nice summaries of dos and don’ts (just like BakeWise and CookWise), and what really makes the book stand out is that is so compact yet still comprehensive. It’s one of those books I actually use when cooking. Many other books have a little too much text - you have to read a lot to pick up the key points. Anyway - the reason I mention this is that as I read about the new “Ratio” book by Michael Ruhlman (MR books, MR blog), the German cookbook was the first book that came to my mind.

“Ratio: The Simple Codes Behind the Craft of Everyday Cooking” just appeared this month and promises that it “will unchain you from recipes”. That’s a good thing, because by knowing a couple of basic ratios you can cook anywhere without bringing your recipes. I’m quite fond of books like that and look forward to leaf through it once I get my hands on a copy. Bakers have been using ratios for ages, better known as Baker’s percentages, so the concept is not new. When baking bread, knowing that you need 6 dL for each kg flour will make a decent bread (but not necessarily an exceptional one!). Ruhlman extends the concept and describes 33 useful ratios for the kitchen. One examples is cookies, and it’s as simple as 1-2-3: 1 part sugar, 2 parts fat and 3 parts flour. Add flavor according to taste and baking powder and/or eggs for a lighter texture. Now that’s what I call a short recipe! The only thing that puzzles me is why the book has 272 pages… That’s a good 8 pages to explain each ratio But for an experienced cook the only thing you actually need is the ratio. And if you take a close look at the cover it actually displays several of the ratios. I’ve copied them into the table below so they are easier to read. You can find the remaining ratios (covering Stocks & Sauces, Farçir, Fat-based sauces, Custards) in the Barnes & Noble preview of the book. And if you combine these ratios with some of the flavor pairings from “The flavor bible” you should be ready for a lot of fun in the kitchen!

Many cookbooks suggest the following for boiling eggs: 3-6 min for a soft yolk, 6-8 min for a medium soft yolk and 8-10 min for a hard yolk. If you are satisfied with this, there is no need for you to continue reading. But if you’ve ever wondered whether the size of an egg has any impact on the cooking time you should read on. And if you search the ultimate soft boiled egg we share a common goal! From a scientific view point, a cooking time of approximately 3-8 minutes to obtain a soft yolk is not very precise. A number of important parameters remain unanswered: What size are the eggs? Are they taken from the fridge or are they room tempered? Are they put into cold or boiling water? And if using cold water - when should the timer be started? When the heat is turned on or when the water boils? And would the size of the pan, the amount of water and the power of the stove top matter?

A formula for boiling eggs?
I still remember the very first time I heard about a formula to calculate the cooking time for eggs. I was in high school and as a recipe for the ultimate nerd the egg formula gave me a good laugh. Now - many years later - I count myself to this group of nerds And thanks to the internet, google and Peter Barham’s book “The Science of Cooking” - I have been able to find out much more. I haven’t been able to track down the formula I heard mentioned, but the best documented formula nowadays is derived by Dr. Charles D. H. Williams, a lecturer in physics at University of Exeter. He has set up a nice page on the science of boiling eggs and there’s even a pdf with the full derivation of the formula. Given the starting temperature of the egg T_egg, the temperature of the water T_water and the desired temperature T_yolk (all in °C) at the yolk-white boundry, the cooking time t (in minutes) of an egg with mass M (in grams) is given by:

Whenever possible one should use weight measurements in the kitchen, but some times an accurate balance is not available and in those cases we can turn to the Peter Barham’s formula which is published in “The science of cooking”. The circumference of an egg is easily measured around the thick end using a piece of string and a ruler. I used to have a piece of string with three knots at 13, 14 and 15 cm respectively to make it even simpler. The cooking time t (in minutes) for an egg with a circumference c (in centimeters) is given by:

Former colleagues of mine at the University of Oslo have made a nice flash animation to do calculations with Barham’s formula if you’re not too keen to dig out your calculator. Barham states that his formula gives the time for the centre of the yolk to reach the temperature T_yolk whereas Williams mention in the derivation of the formula that it calculates the time for the yolk-white boundry to reach T_yolk. I’m not able to tell whether the formulas actually differ in this respect or not (comments are welcome on this issue!). A comparison of the two formulas for a set of 50 eggs which I weighed and measured shows that for T_yolk = 63 °C and T_water = 100 °C they are quite similar, except for the larger spread of the circumference measurements (see plot below). For higher T_yolk or lower T_water Williams’ formula consistently gives longer cooking times than Barham’s formula. It remains to be seen which of the formulas will be closer to the truth.

The graph shows the cooking time for 50 eggs (sorted by increasing mass) calculated from the mass and circumference using the two formulas shown above with T_yolk = 63 °C, T_water = 100 °C and T_egg = 4 °C. For the given conditions the two formulas give similar results. The most striking lesson learnt is that measuring the circumference is in fact not very accurate, hence the larger spread of these points.

The doneness of the egg depends on the temperature of the white and the yolk. Egg white starts to coagulate in the range 62-65 °C. At these temperatures it is the most heat sensitive protein, the ovotransferrin, which constitutes 12% of the egg white, which coagulates. The major protein of egg white, ovalbumin, makes up 54% of the white and doesn’t coagulate until the temperature reaches 80 °C. The yolk begins to thicken around 65 °C and sets around 70 °C. Further heating to around 80-90 °C produces the crumbly texture typical of hard boiled eggs. Many of these changes are nicely illustrated in the picture of sous vide cooked eggs below, but the changes are also summed up in the following table:

At sea level, the temperature of boiling water is 100 °C. At higher altitudes, the boiling is lowered. As a rule of thumb, the boiling temperature of water is lowered 0.3 °C for each additional 100 m above sea level. For an accurate calculation, check out his calculator. As we shall see later, the formula can of course also be used prepare eggs at sea level, using water kept at temperatures less than 100 °C. Lastly we must know the starting temperature of the egg which will typically be 4 or 20 °C.

Based on T_water = 100 °C, T_egg = 4 °C and T_yolk = 63-67 °C I’ve prepared plots for the range of 50 eggs used in the previous graph. If the circumference or mass of an egg is known, the boiling time in minutes can easily be determined from the graphs. I’ve also prepared downloadable pdfs with the circumference and mass plots.

Cooking time for eggs with given circumference or mass to reach to reach 63, 65 and 67 °C respectively at the yolk-white boundry with T_water = 100 °C and T_egg = 4 °C (click for larger image or download pdfs with circumference and mass plots)

But is this the perfect egg?
No actually not… keep reading! The problem with using boiling water is that while you do heat the yolk to the desired temperature, you have virtually no control with the temperature of the white. If your water holds 95-100 °C, so will the white (or at least the outer most part of the white). This gives it a firm, rubbery texture. So the problem is, to put it differently, that we want to heat the yolk to somewhere above 65 °C, but we do not want to heat the white above 80 °C. The solution to this problem is to “boil” the egg at a temperature lower than 100 °C, which means not to boil it at all but rather sous vide it! Eggs are perfect for sous vide because you can just drop them into the water bath as they are. No plastic bags or vacuum packaging are required. Douglas Baldwin has cooked eggs sous vide for 75 min at different temperatures ranging from 57.8 to 66.7 °C as shown below. Notice how the egg whites and egg yolks change at the different temperatures.

Composite image of eggs cooked sous vide for 75 min at the indicated temperatures (Photo: Douglas Baldwin. Picture used with permission.)

The surprising thing with some of the sous vide eggs is that they are inverted (or opposite boiled). The white is still runny while the yolk is set. If you would like to try this but don’t have a thermostated water bath for sous vide you can improvise a little. The thermostat most people do have in their kitchen is the baking oven (at least those with electric stoves). Preheat your oven to 70 °C. Then heat 1 L of water to 65-70 °C, put the eggs in, cover with a lid and leave the pan in the oven for one hour. The tricky thing here is that oven thermometers are notoriously wrong so use a separate handheld thermometer to check your oven. With some trial and error you should be able to obtain an inverted egg with a runny white and a yolk that has set.

Although scientifically amusing the inverted egg isn’t really desirable form a culinary viewpoint - the white is a little to runny. Regrettably the formulas presented above aren’t of much help either. They fail because they only take time and not temperature into account. The perfect soft boiled egg in my opinion would have an egg white which is heated to around 70-80 °C and a yolk with temperatures ranging from 64 °C at the yolk-white boundry to about 60 °C in the center. I guess it would be possible to prepare such eggs in a sous vide water bath held at 75-80 °C in less than an hour. A further complication of cooking eggs in real life is that they continue to cook when removed from the hot water. Normally this is alleviated by shocking the eggs in cold water, but if cooked at a lower temperature this could possibly be omitted. I will start experimenting to find a perfect mass-time-temperature combination with a time window that’s as large as possible, and I’ll report the results in a future blog post. And these experiments will also include a test of the recipe for eggs cocotte by Joël Robuchon, found via Chubby Hubby’s post on slow-cooking an egg.

Exotic soft boiled eggs
In his book “Off on a comet”, science fiction author Jules Verne shows that he was actually aware of the possibility of “boiling” eggs at a temperature lower than 100 °C. He has correctly observed that water boils at lower temperature in high altitudes, and that on a fictional comet of appropriate mass, water will boil at 66 °C. The temperature is wisely chosen, because by keeping eggs at 66 °C, you really can’t do anything wrong. From the last paragraph of the excerpt it seems that the eggs were not fully cooked after “a good quarter of an hour”. Of course, there is also no mention about the size of the eggs, so any further speculations end here. But I’ll rather leave it to you to read the excerpt from the Gutenberg e-text version - it’s quite amusing:

The skillet was duly set upon the stove, and Ben Zoof was prepared to wait awhile for the water to boil. Taking up the eggs, he was surprised to notice that they hardly weighed more than they would if they had been mere shells; but he was still more surprised when he saw that before the water had been two minutes over the fire it was at full boil.

“By jingo!” he exclaimed, “a precious hot fire!”

Servadac reflected. “It cannot be that the fire is hotter,” he said, “the peculiarity must be in the water.” And taking down a centigrade thermometer, which hung upon the wall, he plunged it into the skillet. Instead of 100 degrees, the instrument registered only 66 degrees.

“Take my advice, Ben Zoof,” he said; “leave your eggs in the saucepan a good quarter of an hour.”

“Boil them hard! That will never do,” objected the orderly.

“You will not find them hard, my good fellow. Trust me, we shall be able to dip our sippets into the yolks easily enough.”

The captain was quite right in his conjecture, that this new phenomenon was caused by a diminution in the pressure of the atmosphere. Water boiling at a temperature of 66 degrees was itself an evidence that the column of air above the earth’s surface had become reduced by one-third of its altitude. The identical phenomenon would have occurred at the summit of a mountain 35,000 feet high; and had Servadac been in possession of a barometer, he would have immediately discovered the fact that only now for the first time,
as the result of experiment, revealed itself to him–a fact, moreover, which accounted for the compression of the blood-vessels which both he and Ben Zoof had experienced, as well as for the attenuation of their voices and their accelerated breathing. “And yet,” he argued with himself, “if our encampment has been projected to so great an elevation, how is it that the sea remains at its proper level?”

Once again Hector Servadac, though capable of tracing consequences, felt himself totally at a loss to comprehend their cause; hence his agitation and bewilderment!

After their prolonged immersion in the boiling water, the eggs were found to be only just sufficiently cooked; the couscous was very much in the same condition; and Ben Zoof came to the conclusion that in future he must be careful to commence his culinary operations an hour earlier. He was rejoiced at last to help his master, who, in spite of his perplexed preoccupation, seemed to have a very fair appetite for breakfast.

There is in fact no need to head off to other planents to find examples of low temperature prepared eggs. If you go to Japan you’ll find onsen tamago which litteraly translates to “hot spring eggs”. Originally baskets of eggs were lowered into hot springs, but the temperature of hot springs vary so I imagine that there were several types of onsen tamago available (does anyone happen to know the exact temperature of the hot springs used?). After cooking the egg is typically cracked into a bowl of dashi soup with mirin and soy sauce. The challenge of preparing onsen tamago eggs at home is accurate temperature control (just as with sous vide in general). One tip I found was to place the egg on top of rice that has just cooked in a rice cooker. Leave the eggs to “cook” for about one hour while the “keep warm” function of the rice cooker is turned on.

Eggs boiled in onsen (japanese: hotspring), Nagano, Japan (Photo: Miya.m. Permission: GFDL, cc-by-sa-2.1-jp).

I’ve been told that in Finland some saunas are equipped with egg racks. Depending on where the rack is placed one could probably chose between hard boiled and soft boiled eggs. But the sauna would have to be kept warm for a long time due to the slow heat transfer from the hot air. And talking about eggs and saunas: If the eggs are placed directly on the hot stones they will not only be hard boiled, but actually turn completely brown and aquire a nutty flavor. In Korea such sauna eggs are known as Maekbanseok gyeran.

Other aspects to consider when boiling eggs
An egg has somewhere between 7000 and 17000 pores, meaning that water slowly evaporates (the density decreases from 1.086 g/cm³ by 0.0017 g/cm³ daily). This is also why eggs age faster at room temperature than in the fridge. Beacause of the pores, eggs should not be stored next to foods with a strong smell such as onions (unless of course, you want onion flavored eggs). When boiling eggs it is not uncommon that they crack. The most obvious reason is that they are dropped into the water and hit the bottom of the pot. Another reason for cracking is the expansion of trapped air at the blunt end of the egg. This air cannot escape fast enough through the small pores. Conventional wisdom has it that piercing a small hole in the blunt end will let expanding air escape to avoid cracking. It turns out someone has actually scientifically tested this (with 1000 eggs) and their finding was that there was little cracking for fresh eggs, regardless if they were pierced or not. Piercing reduced the cracking of 5-day old eggs and totally eliminated cracking of 28-day old eggs. The authors theorize that the air pocket grows due to evaporation (meaning there is more air to expand) and that the egg shell of fresh eggs is porous but that the pores gradually become clogged upon storage. Curiously the abstract concludes with the following sentence (this was written in 1973, but it’s still quite unusual for a scientific journal):

Housewives should pierce eggs before boiling them, since if they are fresh it will do no harm and if they are stale it will prevent splitting.

We can safely assume that the advise holds true for men as well! Apart from piercing holes to avoid cracking it is possible to reduce the potential damage from cracking by addition of salt or vinegar to the water. This will help the egg white coagulate faster and thus plug any crack formed.

Picture of egg shell pore (Photo: Jim Ekstrom. Permission: Freeware for non-commercial use).

It’s time for a new round of “They go really well together”. For TGRWT #17 the challenge is to pair apple with rose, in particular Cox Orange or Elstar apples in combination with Damask (Rosa × damascena). The hosts this time are Malin and
Lisa, and Malin explains explains a litte about the chemistry behind the pairing both in English and Swedish. The deadline is May 8th so you get a little extra time for this round. By coincidence rose appears in TGRWT twice in a row, but I can assure you that the hosts of the March and April round did not know about each others choices when they were made. If you bought a bottle of rose water for last round I’m sure there’s a little left. You might even be lucky to get hold of fresh rose leaves now that summer is approaching. For inspiration on how rose combines with chicken, do check out the round up of TGRWT #16 over at Supernova Condensate.

I just discovered that The Atlantic features a blog by Grant Achatz of Alinea. Under the title “Back of the house” we get a peek “Inside the restlessly creative mind and kitchen of Grant Achatz” according to The Atlantic. Grant has so far reported from the Madrid Fusion in January (four posts) and in the latest post he describes how a visit to Japan has inspired him to explore manipulation of the environment at Alinea. Comments are allowed and Grant is actively involved in the discussions. Recommended reading!