Archive for the ‘tips & tricks’ Category

Hydrocolloid recipe collection v.2.2

Friday, December 19th, 2008

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.

Name of meat cuts

Friday, December 19th, 2008

In the last couple of days I’ve encountered a special challenge when reading (and writing) English as a non-native speaker. It’s related to food and more specifically the different meat cuts available. As I read about sous-vide cooking I often sit back and wonder what the cut is called in Norwegian. I’ve found a useful list at Doorway to Norway (quoted below), but my question to you is: Do you know about better or more extensive lists? Are there also differences between American and British English? And more generally: Is there any authoritative source for the translation of food related terms?

English = Norwegian
beef brisket = oksebryst
sirloin = mørbrad
bottom round = rundbiff
round steak = flatbiff
chuck = høyrygg
roast beef = roastbiff
club steak = entrecotè
tenderloin = indrefilet
T-bone = T-ben
boneless strip = ytrefilet
ground beef = kjøttdeig
short ribs = bibringe
flank steak = slagside
stew meat = bankekjøtt

There are a couple of false friends here. The Norwegian translation of “round steak” literarily means “flat steak”, whereas the Norwegian “Rundbiff” which litterarily mens round beef is equivalent to the English “bottom round”. Easy to get confused here…

Sous-vide cooking joy

Sunday, December 14th, 2008

Having received a real kitchen gadget before the weekend, I certainly had to do some sous-vide experiments. While shopping I looked specifically for meat that was already vacuum packed in plastic bags as I do not have a food saver. There is actually a decent selection available and I got a 1.5 kg roast beef and a chicken breast (a particularily nice one, bred according to the Label Rouge principles). The nice thing about the meat I got was that the packaging had temperature suggestions. Even though I have books and tables and access to the internet it’s always nice to have this information available exactly when and where you need it. And as I dropped the meat into the water bath it occured to me that this was so simple (not that I shun complex recipes), so clean (I’m not afraid of a messy kitchen) and so convenient (I’m not at all a fan of fast food) that given the expected end result this is probably how very many people will prepare their meat in a not to distant future! So to all farmers, butchers and producers of immersion circulators – I hope you read this and act accordingly ;)


(more…)

Wonders of extraction: Oil

Friday, October 24th, 2008


Brazilian chiles in oil (very nice with Moqueca!)

Oils and fats are long molecules which are mainly non-polar and hence the opposite of water which is a polar molecule. Ethanol which has both a polar and a non-polar end falls in between oil and water. I’ve covered extractions using water and ethanol previously. That water and oil are opposites is easily observed by the fact that they don’t mix, and because of it’s lower density oil floats on top of water. This property allows us to easily separate water and oil.

Volatile molecules – the molecules that we detect by their smell – are mainly non-polar and therefore soluble in oil. This is one reason why foods with fat often have a different and often better flavor compared with their fat-free counterparts (fat of course also influences mouth feel etc.). Everytime you cook with oil it will actually help extract aroma (or smell flavorants) from the food ingredients and deliver these to your nose.

There are several oil extracts used in the kitchen, and the nice thing about them is that the oil extracts aromas and then protects them from the air. This is good as it prevents oxidation of the aroma molecules, but in some extreme cases bad because the anaerobic conditions may promote growth of botulinum spores – more on that in the last paragraph. When the flavored oil is added to a dish you get can immediately perceive the aroma. If the oil is tasted pure it serves as a carrier for the aroma giving a small explosion in the mouth (or nose to be more precise…). Some examples I can think of where the oil plays an important role in extracting and delivering aromas are: pesto, tapenade, mayonaise, aioli, curry paste (and all other spice pastes), chili oil and truffle oil to mention a few. Notice that in most of these the source of the aromas is still present in the oil.
(more…)

Kamikaze cookery

Wednesday, October 8th, 2008

There’s a new weekly cooking show you shouldn’t miss. It’s about cooking and science, or “Kamikaze cookery” to be more precise. And there’s a good dash of humor as well which doesn’t hurt. The first episode out is on how to cook that perfect steak (it’s embedded below, but on their site you can watch it at a better resolution). I’ve covered the topic before in my post on DIY sous-vide, but their video is much more entertaining :) They use a vacuum cleaner to suck out the air and a blow torch for the Maillard reaction! There is also a blog accompanying the videos. Hereby recommended!

Hydrocolloid recipe collection v.2.1

Wednesday, June 25th, 2008

An updated version of “Texture – A hydrocolloid recipe collection” is now available for download (version 2.1). The version includes corrections of typos, minor additions to the property tables plus an important update in the gelatin section and a recipe for agar filtration. Read on for details!

I’m grateful for feedback from several readers pointing out that the size of gelatin sheets is made to compensate for different bloom strengths. In other words, one gelatin sheet will gel a given amount of water, regardless of the size of the gelatin sheet. To the best of my knowledge, this convention seems to have been adopted by most gelatin producers.

All gelatin based recipes have been updated to reflect this and most of them now give the amount of gelatin both in grams (for a platinum type, 240 bloom gelatin) and in number of sheets. I’ve also included a formula for conversion between different bloom strengths. This formula differs from what has been published earlier (no square root), but by testing the formula for given gelatin sheet bloom strengths and weights I got better results by simply multiplying the mass by the ratio of the bloom strengths. If you know more about these formulas, please leave a comment or email me.

Checking the gelatin recipes I discovered that the recipe “Strawberry spheres” originally called for “Sosa vegetable gelatin” which is not gelatin but a mixture of carrageenan and locust bean gum which are dispersed with maltodextrin. Since the exact amount of carrageenan and locust bean gum are not known I’ve deleted the recipe (but I’m sure you could achieve the same coating effect with plain gelatin, perhaps a 3-4% solution to render it viscous so it will cling the the spheres).

Thanks to feedback from a reader there is also recipe now for agar filtration (based on a Spanish forum post). This works just like gelatin filtration, but is much faster. Apparently you get more or less the same results with regard to clarity, flavor and color.

If printing the collection, make sure the hydrocolloid properties table is rotated so it prints correctly. This table is presented in landscape format. The right most column of the first page is gelatin – if you don’t see it, try printing these pages again. The pages are optimized for printing on A4. If printing on Letter sized paper, make sure you check the “resize” or “fit to paper” option in your pdf reader.

Thank you for comments, corrections, recipes and other feedback! As always, I can be reached at webmaster a t khymos d o t org.

Wonders of extraction: Ethanol

Sunday, June 8th, 2008


Extraction of cherries with ~45% ethanol in water

Ethanol is a molecule with both a polar and a non-polar end, so it’s properties are somewhat in between those of water and oil (which will be the topic of the next post in this series about extraction). This is easily illustrated by the fact that both water and oil are soluble in pure ethanol (albeit not at the same time – adding water to ethanol reduces the solubility of oil). Many taste molecules are polar whereas most aroma molecules are non-polar, and the good thing is that ethanol can be used to extract both groups of compounds.

I belive the most widespread use of ethanol for extractions in the kitchen is for sweet liqueurs where fruits or berries are extracted with ethanol and the extract is sweetened with sugar. The word liqueur comes from the Latin word liquifacere which means “to dissolve”, and this is essentially what happens – the ethanol and water extract and dissolve flavor and color from the fruit.

Some also make their own spirits by infusing spices and herbs. One example is aquavit which is based on carraway combined with a number of other spices for complexity such as dill, coriander, anis, fennel, liquorice, cardamom and lemon. Commercial aquavits are distilled, but at home it’s suffices to filter of the spices and herbs. As a result home made aquavits are always amber colored (such as the one pictured in a previous post).

For extractions like these, one always uses diluted ethanol, typically 30-60% ethanol in water would be used, and most often somewhere around 40-50%. One reason for this is that higher concentrations of ethanol would extract to many bitter and astringent compounds. Another reason is that in some (most?) countries it is illegal to posess, buy and/or sell ethanol at higher concentrations for consumption (pure ethanol for technical use is denatured if sold in normal stores and requires special permissions if used in laboratories).

Apart from the steping herbs and spices in ethanol to make liqueurs, the only other example of relevance for the kitchen I can think of is for extraction of vanilla beans to make pure vanilla extract. This is quite surprising actually, and although I really don’t know if ethanol is used for extraction in professional kitchens, it is my impression that ethanol extractions are underutilized in the kitchen.

There are several benefits with ethanolic spice and herb extracts:

  • fast – no need to wait for the spices to be extracted since they have been “pre extracted”, you can taste the dish immediately and add more spice extract if necessary
  • no residues – seeds, leaves or bark are filtered off before use
  • convenient – spice extracts are an excellent way of adding clean, concentrated aromas
  • stable – spice extracts keep very well (although the storage may also change the flavor profile somewhat and “mature” the flavor)
  • new flavors – some spices and in particular herbs will change upon extraction and storage and this can open up new possibilities (this needs quite some experimentation though – some herb flavors change to the worse…)

What are your experiences with ethanol extractions in the kitchen?

Wonders of extraction: Water

Tuesday, June 3rd, 2008


Extraction of peppermint leaves with hot water

Water is a polar molecule, meaning that one end has a small negative charge and the other a small positive charge. Because of this water is a very good solvent for other polar molecules and ions. For instance water is the solvent of choice for substances that provide taste, be it salt, sour, sweet or bitter as these are normally quite polar molecules.

A general rule is that the solubility of molecules and ions increases with the temperature of the water. Extractions are therefore faster if the water is boiling. This is the reason why we use hot water to extract tea leaves or ground coffee beans, even if we want to prepare ice tea or ice coffee. But by lowering the temperature and extending the extraction time we can change the relative proportion of what we extract. It therefore makes perfectly sense that different temperatures are recommended for different types of tea. Using different temperatures for the same kind of tea will of course also influence the flavor profile.

Polar molecules are more easily extracted than non-polar molecules. This is evident if we leave a tea bag for a long time in hot water. The bitter taste is due to the slow extraction of large polyphenol molecules which are less soluble in water. If tea is brewed at a lower temperature, less of the bitter tasting substances will be extracted.

Although water is polar, less polar and even non-polar substances can be extracted with water, especially if the water is boiling hot. You do this every day when prepare coffee. If you take a close look at cup of freshly brewed coffee you can notice small pools of oily substances floating on top of the coffee. The more severe conditions used when extracting coffee to make an espresso ensure that even more oily substances are extracted. Other examples of extraction using water in the kitchen include preparation of stock, soups and gravies.

The principle of extraction is simple, but a number of questions remain largely unexplored with regard to flavor: How do ions affect extraction? What role does pH play? How does temperature influence flavor? There is surprisingly little research on this that includes a sensory evalution.

Liquid nitrogen ice cream

Monday, June 2nd, 2008

I recently became aware of an excellent site focusing solely on liquid nitrogen ice cream! Ever heard about “The institute for liquid nitrogen ice cream experimental studies” or TILNICES for short? They’re located at the Department of Chemistry at the Tennessee Technological University. It seems that the site is still under construction, but several recipes are already available plus a number of papers (available for download as pdf files).

[Thanks to John Placko on the MG mailing list for mentioning the site]

Ten tips for practical molecular gastronomy, part 9

Saturday, May 31st, 2008

9. Keep a written record of what you do!

Wouldn’t it be a pity if you couldn’t recreate that perfect concoction you made last week, simply because you forgot how you did it? Last year I made a vegetable soup to which I added garam masala and pepper. I was cooking ad lib, adding a little of this and that without taking notes… Which is annoying, because it turned out very nice! It had a remarkable aftertaste which gave me a somewhat dry feeling on the back of the tongue and it reminded me of mangoes. Even immediately after the meal I wasn’t able to recall all the ingredients.

As an undergraduate student I took an organic chemistry lab course, and I remember we were told not to use post it notes or small pieces of paper for taking notes. Everything should be recorded in a proper journal or – if necessary – small note books. Having finished my Ph.D. a couple of years later, I can only testify to this. Everything you do – be it in the lab or in the kitchen – should be recorded immediately in a journal. It’s amazing how something that was obvious one day, slips your mind a week or month later.

There is a wonderful Donald Duck story by Volker Reiche entitled “The soul of science” (the original appeared in 1981 in the Dutch Donald Duck magazine). At a point “Professor Duck”, who actually works as a janitor in a lab, utters the words “Careful notes are the soul of science” as he is caught experimenting. This is true also for the kitchen and experimental cooking. A German translation of the story was reprinted in the article “Das Leiden des cand. chem. Donald Duck” (open access) in case you want to read the whole story.


Careful notes are also the soul of kitchen science!

When taking notes it’s essential that you are able to re-cook the dish yourself. But if no one else is, the notes are of limited value. The biggest source of uncertainty in the kitchen is the widespread use of volume for measuring powders. This can best be illustrated by the question: How much does a cup of flour weigh?

I bumped into this when I began baking no-knead bread (recipe). I converted the recipe to metric units using an online calculator, but the no-knead bread wasn’t a huge success. The problem was that there is no simple answer to the question “How much does a cup of flour weigh?”. Cooking conversion online states that a cup of all-purpose flour weighs 99 g. King Arthur Mills claim that all their flours weigh 113 g/cup. USDA states 125 g/cup and Gold Medal 130 g/cup. Some cookbooks have settled at 140 g/cup (apparently because this is about half way between a loosely and densly packed cup) and if the flour is hard packed you can reach 160 g/cup. In other words – when following a recipe you would need to know how the volume of flour was measured in order to use exactly the same amount of flour. Some recipes call for “spoon and level” or “scoop and level”, but many do not include any information about this.

My recommendation is to weigh all dry ingredients (and preferably also the wet ingredients). A normal digital kitchen scale typically has a resolution of 1 g with an accuracy of +/- 5 g and they are quite affordable. Weighing liquids is also far more accurate than the average volume measurement in the kitchen. If the scale has a “tara” function it’s also much faster as you can zero the display after each ingredient you add. It shouldn’t come as a surprise that I’m not the only chemist advocating weight measurements in kitchen. And it’s not difficult finding other sites in favor of weight measurements either.

It therefore puzzles me why recipes that call for the following are still so abundant:

1 pack of instant yeast
1 envelope unflavored gelatin
1 gelatin sheet (see comment #4-5)
1 sachet powdered pectin
1 tablespoon liquid pectin
1 stick of butter
… and the list goes on

The only exception to the general advice on weighing ingredients is when very small quantities are used. This could be spices, food coloring or hydrocolloids. With normal kitchen scales, you’ll be better of using volume measurements for amounts less than 5 g (equal to a teaspoon if measuring water). Otherweise it’s worthwhile mentioning that scales with a 0.1 g and 0.01 g readout are getting cheaper and cheaper.

*

There is a summary of the “10 tips for practical molecular gastronomy” posts. The collection of books (favorite, molecular gastronomy, aroma/taste, reference/technique, food chemistry) and links (people/chefs/blogs, webresources, institutions, articles and audio/video) at khymos.org might also be of interest.