Low-temperature cooking might save restaurants money

Last year, I had the pleasure to act as a co-supervisor for two students at in their final project for the Food and beverage management study at the University of Stavanger. The focus was low-temperature cooking.

The students, Eirik Nestavoll and Martin M. Stokkan (both chefs), attended this as a continuing professional development study. The aim of their experimentally angled final project was whether "new cooking methods" might give economic gain to hotels.

Blue cheese and plum soft ice cream (TGRWT #18)

Pastry chef Aidan Brooks has posted the invitation to join in on episode #18 of "They go really well together" (TGRWT). The idea is that foods with one or more flavour compounds in common will taste well in combination; the concept of flavour pairing. This month's ingredients are plum and blue cheese.

I've found that simple dishes such as milk shakes, smoothies and ice cream (this post) provide excellent matrixes for testing flavour pairings. Things are kept simple allowing for the pure flavours to come out, not being swamped by lot of (distracting) flavours from other ingredients. As such, milk and/or cream pose a good base. So this time, I went for a very simple straightforward recipe for soft serve ice cream. At the same time, it gave me the opportunity to test our new Bamix immersion blender (a common blender or smoothie machine will probably work well too).

Culinary precisions, part 3:3. Students as "culinary mythbusters"

Among the challenges in science education are creating quality inquiry-based teaching methods as well as promoting students' argumentation skills. Both these topics might be seen as parts of what goes as "the nature of science". In this last post of three, I argue that statements about food and cooking might be an excellent starting point for learning argumentation as well as inquiry, as well as content knowledge, while dealing with real-life problems with meaningful purposes.

The two first posts:

• Culinary precisions part 1:3. Collecting statements about food and cooking
• Culinary precisions part 2:3. Analysing statements about food and cooking

In part 1, I suggest that there might be a good idea to collect statements about food and cooking (culinary precisions) in an open database, whereas part 2 argues for the use of argumentation patterns in the analysis of such statements. For explanation of the term "culinary precisions", see part 1.

Background; challenges in science education

There is abundant literature, as well as political signals, that point to the need for development of fresh approaches to science education, not the least because of an alarmingly low interest in science and mathematics. Furthermore, the last years have seen a need to shift towards a science education in which "the nature of science" is taught as well as content knowledge; students at all levels should gain experience with scientific inquiry, argumentation etc. There are of course numerous ways this challenge might be taken on.

One problem when it comes to inquiry and argumentation is to find experiments, topics and investigations which are open-ended real-life problems. It's not very exciting to do "inquiry" if you know that the teacher has got the answer in his/her drawer. But what if the thing you were analysing, discussing and experimenting was a real problem? And even more, that others, such as a scientist or the general public, would be interested in the result you came up with? Such scenarios do exist (such as sustain.no, which in fact is a database), but I feel pretty confident that there is need for a range of such approaches, covering various topics.

Culinary precisions, part 2:3. Analysing statements about food and cooking

Statements on what to do, how to do it, and occasionally why to do so, are abundant in the world of food and cooking. This is the second post of three, and deals with a rationale for analysing such statements. The third post will deal with the potential of using this for educational purposes, both in science and food disciplines.

In the first post, I wished for, and tried to give good reasons for building a database of statements on food and cooking (culinary precisions). For an introduction and definition of culinary precisions, see part 1.

The two other posts:

• Culinary precisions part 1:3. Collecting statements about food and cooking
• Culinary precisions part 3:3. Students as "culinary mythbusters"

Culinary precision = claim
A culinary presicion is a statement about something related to food or cooking, such as

• "sprinkle lemon juice on sliced apples/pears, and the fruit will not go brown"
• "you should avoid piercing meat as the juice will flow out resulting in a drier piece of meat"
• "you should cut off the ends of a roast before putting it in the oven"
• "when canning fruit in glass jars, the jar must be stored upside down"

Some precisions contain reason(s) for why one should follow them, others give a consequence that might occur if you don't follow the advice given. During a course on argumentation in science education, I realised that culinary precisions might indeed be considered to be claims. Occasionally, these claims have some data or warrants to explain why you should follow the advice given, and sometimes they don't (first case: "if you do A, B will happen", second case: "do this"). Hence, we are in the domain of arguments.

A system for analysing statements, claims and arguments
For analysis, understanding and testing such culinary precisions, it'd be good to have some coherent system or scheme to fit it into. Argumentation theory has struggled with the analysis of claims and arguments all the way back to Aristotle (and probably earlier). However, the "traditional" (syllogistic / syllogism) way of analysing an argument does only work for a certain type of arguments, and often fail to incorporate all aspects of real-life problems and discussions. Hence, other perspectives on logical arguments have appeared. Among these is the one presented by philosopher Stephen Toulmin. The Toulmin argumentation pattern is a way of organising, analysing and visualising practical real-life arguments, and is often shown in a diagram:

Toulmin's argumentation pattern (click for larger image)

Culinary precisions, part 1:3. Collecting statements about food and cooking

Is it really true that you shouldn't rinse, but rather brush, mushrooms? Should a steak be seared to keep the juices inside? The world of food is full of statements on how to do things, many of which are rooted in tradition. When tradition and science meet, interesting things might happen. This is the first post of three on the topic. This first part argues for an open database of such statements, including analysis. The second will deal with a rationale for analysing such statements using argumentation patterns. In the third post, I discuss the potential of using this for educational purposes, both in science and food disciplines.

The two other posts:

• Culinary precisions part 2:3. Analysing statements about food and cooking
• Culinary precisions part 3:3. Students as "culinary mythbusters"

A short introduction for newcomers: Dealing with statements on food and cooking is among the major objectives of molecular gastronomy (MG for short, a term and field which enjoys quite a lot of debate, both in terms of its name and also because it is a field in it's infancy. There is a debate running in various channels, but discussing MG in general is not the topic in this post). As defined by Hervé This, such statements are called culinary precisions. You might just as well say "old wives' tales", "culinary proverbs", "cooking rules/advice", "know-how", "adages" or "maxims". I have no strong preferences on what words to use for this, but thus far I think "culinary precisions" does the trick and will adhere to that.

There are a few publications speaking of culinary precisions (such as these four). To my knowledge most publications are focussed on speaking of this phenomenon rather than doing a real analysis. For several reasons, this would be very interesting to follow up. I've found only one collection on the www, by Hervé This, which is in French (unfortunately I don't speak French and have to rely on automated translations). However, this collection lacks the analysis aspect.

The INRA web page of culinary precisions (English google transl.)

Cooking pit revisited - temperature logging

Spring and summer time equals cooking pit time. This time we did some more serious temperature measurements, showing interesting results. A brief report follows...

Every May/June we take our food culture students out for some primitive cooking, ref. the previous post Primitive food, heat transfer and a day out. This time we did some more serious temperature logging with the help of Type K 4-Port Temperature Sensor connected to a Pasco datalogger.* This enabled us to monitor temperatures automatically at four different places in the cooking pit at one time:

• inside of the pit, at the bottom
• inside of the pit, at the top
• inside the trout cooking
• 10-15 cm outside the pit, ca. 25 cm deep (to monitor the heat loss through the soil)

Temperature plot. Click for large version

Most noteworthy is the temperature difference between the bottom and top, since the food and rocks are laid in layers. This is very interesting in terms of where to place food the next time we'll use this method. One might also exploit this to cook different foods in the same pit (i.e. meat and chicken or fish); place the meat at the bottom and place the fish directly on top of the meat. Also, note that the fish, being wrapped in foil, levels off at 110 °C. I guess this is due to the large water content in a closed package. Hence, this isn't the method if you aim at sous-vide type results. The flavour and texture is however still very good, not at all mushy.

This time we dug two pits

• Pit 1: lamb's leg and potatoes, somewhat less than 3 hr cooking time
• Pit 2: Trout and chicken, 1 hr 10 min. cooking time (see temp. plot)

Data logger with 4-port K-type sensor. More pictures in previous post

We're on our way to publish a web based teaching plan on this topic, including historical, physical science, and food related information at www.naturfag.no/mat (Norwegian national school science web pages) and www.natursekken.no. All in Norwegian (but google and babelfish make increasingly good translations). I'll post a note when it's out.


Reference:
Wandsnider, L. "The Roasted and the Boiled: Food Composition and Heat Treatment with Special Emphasis on Pit-Hearth Cooking." J. Anthr. Arch. 1997, 16, 1-48. (This ref. is most relevant for indigenous American traditional pit-hearth cooking, using rather different foods. For Scandinavian prehistoric methods, see the previous post and coming teaching plan)

www.naturfag.no/mat, English translation
www.natursekken.no, English translation



* The K type thermocouples measure a range of -200 - 1000 °C! Although the probe sleeves are limited to 482 °C, this is sufficient for use inside the pit

Chocolate part 3:3 - making your own instant cocoa

During graduate studies, we often wished for a "journal of unsuccessful chemistry" for the benefit of all the failed experiments we do. What if there was a journal where we could look for the experiments we were planning, and see if someone else had tried it and failed? This is one of those stories.

Cocoa powder has this property that it is hardly wetted by water. The result is

• when making cocoa, thorough agitation or stirring is necessary to avoid lumps and cocoa powder floating on top
• eating plain cocoa powder is not a very pleasant experience
  

In my search for info on why chocolate seizes (chocolate part 1:3) and shaping chocolate (chocolate part 2:3), I came over three papers on the wetting properties of cocoa and cocoa granules. In short, they stated that if I could turn cocoa powder into a granulate rather than the fine powder it is, it might disperse more easily because it'll interact better with the water molecules. Also, I figured, it might taste better in it's dry state as it's easily wetted by the saliva in my mouth.

Would it be possible for me to make my own instant cocoa, or maybe some palatable cocoa powder for sprinkling on top of dishes? If so, I could make my own blend and use quality cocoa rather than the sugar-loaded mixtures that are sold in grocery shops.

Granulating cocoa powder
Omobuwajo et al. brought about an easy method of making granules that are readily wetted by water. They simply heated the cocoa powder on metal plates. No need for expensive industrial machinery and additives. They investigated the granulation related to various cocoa-to-sugar ratios and conclude that the two best instant cocoa mixes were made by rapid heating of sugar and cocoa in 3:1 and 4:1 ratios, using fine sugar (0.23 mm), giving granules of 0.18 mm size. Now, if heated metal plate = skillet on my stovetop, I might make my own instant cocoa powder, or...?

A mixture of 9 g plain cocoa powder and 27 g sugar was heated in a pan on medium high heat (a little below maximum) with continuous stirring for 5 minutes.

Result: yes, the cocoa is granulated (right). No, I was not able to make granules that disperse more easily in a reproducible manner (some times it was easily wetted, sometimes it wasn't). Also, the powder tasted somewhat different due to the heat treatment (surprise...), without being more palatable than pure cocoa powder mixed with sugar.

Conclusion: more testing is necessary, several parameters to vary (temperature, time, stirring). This might probably work, but I don't find this interesting enough to spend more time on experimenting.

Wetting properties of cocoa powder
Wetting by water is closely related to whether something is hydrophilic or hydrophobic. If it's hydrophilic, it loves water and wetting occurs easily; water spreads out on the surface. If it's hydrophobic, the opposite occurs, such as on Gore-Tex. Wetting is not limited to water, and other solvents also possess wetting properties. These properties are in turn closely related to the surface energy. A general rule is that media/material with similar surface energies will possess similar wetting properties.

Galet et al. reported that the surface energy of cocoa powder is considerably lower than surface tension of water. Result: water and cocoa powder don't mix very well (surprise...). The bad dispersion behaviour of cocoa is caused by a number of phenomena, and one is the hydrophobic nature of cocoa, the fat content being 10–12% in cocoa powder. The mean particle size of cocoa is commonly around 16 micrometres (0.016 mm), but the size distribution is wide. The smaller the grains, the more difficult is the dispersion. Granulating the powder (making grains of 0.02 mm - 2 mm) resulted in enhanced wetting properties.

Partly, the bad dispersion properties is because of the bad flowability and the cohesive forces of the powder. The cohesion results in solid agglomerates, and the shear forces are not sufficient to break the cohesive forces between the grains. In plain words: cocoa powder lumps up in water, simply floating on top (another surprise...).

Cocoa powder in alcohol
A conclusion that may be drawn by this, is that liquids with lower surface tension (surface energy) than water might wet cocoa more easily. Galet concludes that liquids with lower surface energies than 40 mN/m will wet the cocoa powder, and that less than 15 mN/m will give perfect wetting. Water has surface energy 72 mN/m, not to wonder why cocoa powder and water doesn't mix well. However, alcohol (ethanol) has surface energy 22 mN/m, and a 40% ethanol in water mixture has surface energy 41 mN/m.

Conclusion: making cocoa flavoured alcoholic drinks should be easier than water-based ones.



References
Galet et al. "Improving the Dispersion Kinetics of a Cocoa Powder by Size Enlargement". Powder Tech. 2003, 130, 400-406.

Galet et al. "The Wetting Behaviour and Dispersion Rate of Cocoa Powder in Water". Food Bioprod. Proc. 2004, 82, 298-303.

Omobuwajo et al. "Thermal Agglomeration of Chocolate Drink Powder". J. Food. Eng. 2000, 46, 73-81.

On chocolate for education purposes:
http://www.exploratorium.edu/chocolate

http://expertvoices.nsdl.org/connectingnews/2009/02/04/the-science-of-chocolate-just-in-time-for-valentines-day

Chocolate part 2:3 - shaping chocolate with a meat grinder

Peter Barham writes that chocolate is shear-thinning; it becomes fluid when shear stress is applied to it, such as by a meat grinder. I went on grinding...

A shear thinning, or pseudoplastic, medium is one that exhibits decreased viscosity when shear stress is applied. The most common example is probably ketchup. Turn the bottle upside down, and the contents stay put. Give the bottle a knock, and annoyingly half the bottle pours out. The same phenomenon is in action when a great landslide results from just a small shaking (i.e. quake) when the area resides on clay ground. Paints also rely on this phenomenon: they are runny when brushed or rolled, but become viscous as soon as the pressure is removed, and thus don't run down the wall.

Following Peter Barham's idea, I had another look in Beckett's "Science of chocolate", which confirmed that chocolate is shear thinning (I suspect that Barham indeed refers to Beckett). In addition, when the softened chocolate firms up again, after just a few seconds, it recrystallises in the same crystal form as before. This is important, because heating-cooling sequences (such as when melting melting) might lead to blooming, such as fat bloom.

My idea was hence: is it possible to use this property to shape chocolate and still avoid the need for apparently laborious and complicated tempering?

My only available equipment for applying shear stress on such a hard medium as chocolate was our kitchen machine with the meat grinder/mincer attached. Running the chocolate through this grinder, the result was what I've termed "chocolate twigs":

Comments on the result
I'm fairly content with the result, but my detailed knowledge of crafting chocolate isn't good enough for me to do a proper evaluation. Even though the texture seems fine, still a nice snap when braking, the colour and surface structure is changed. Maybe that's just OK? However, there are some relevant points to consider:

- The point is applying shear pressure, and not melting the chocolate

• 55% dark chocolate worked fine, whereas milk chocolate softens too much in the grinder (becomes pasty)
  
• the metal grinder needs to be kept cool, since grinding generates heat and might melt the chocolate. Cooling can be done by wrapping a cold moist cloth around the grinder
• the chocolate was kept at room temperature overnight (20-25 °C), but taking the chocolate directly from the fridge did also work (in a previous experiment)
  

- Amount of chocolate
You need quite a lot of chocolate to produce a moderate amount of twigs. In the video above, I spent 400 g. However, the chocolate may be run several times through the grinder. The rest is of course perfectly OK for making other chocolate-based stuff, or maybe practice tempering chocolate...

Coarse or fine mincing screens?
The coarse screen (8 mm holes) was the only one that worked in my hands, as the finer ones resulted in too much resistance. Too much resistance results in clogging and eventually warming/melting the chocolate.

Equipment
Our Kenwood Major (800 W) did the job, but I felt that I overloaded it slightly, especially when it clogged. Dark chocolate is really hard stuff. It'd been fun having some professional extrusion equipment with enough power and temperature regulation allowing to make various shapes. Barham mentions using a pasta machine for "shear shaping" chocolate, but I doubt it'll be strong enough to shape the chocolate, rather than crumble it. Maybe it'll work with milk chocolate?

References
I didn't find any directly relevant scientific literature on this, and the two only references I've found mentioning this (briefly) are

Barham: "The science of cooking"
Beckett: "The science of chocolate"

Also, Corriher's "Cookwise" has quite a lot of information on dealing with chocolate (again, I've still not got my hands on a copy of Bakewise, unfortunately)

Egg cooking calculator

As this year's Easter greeting, Deptartment of Chemistry at the University of Oslo has developed an egg cooking calculator with reference to Martin's Khymos and my Maturfag ("Norwegian fooducation").

The issue of cooking the perfectly boiled egg has been discussed several places, amongst others on Khymos, fooducation, and on "Maturfag" which is fooducation's teacher resource pages at the Norwegian Centre for Science Education (Google translation of the resource pages here). Also, Douglas Baldwin's Practical guide to sous vide cooking has an excellent section on controlled-temperature cooking of eggs.

Formula for calculating the boiling time for eggs. For details and
references, see Khymos egg boiling post

Now, Department of Chemistry in Oslo has converted this formula into an interactive animation/calculator for cooking your Easter egg the way most people do it: in boiling water. This has already collected some attention, amongst others in the national newspaper VG (and supposedly on radio at the national broadcasting corporation NRK during Easter holiday). The cooking time depends on several factors, taken that you use boiling water:

• egg size (circumference around the thick end)
  
• initial temperature of the egg
• altitude (since temperature of boiling water varies according to this)
  
• the way you like your egg (soft, hard, medium)
  

The categories should be rather self-explaining. Click the illustration to go to the calculator
(I love the nifty automatic timer function :)

Tip: For measuring the circumference of the egg, use a piece of string and measure the length that goes around the "belly" of the egg.

Happy Easter holidays

Chicken, rose & rice flavour match (TGRWT #16)

Markus at Supernova Condensate has posted the invitation to join in on episode #16 of "They go really well together" (TGRWT). The idea is that foods with one or more flavour compounds in common will taste well in combination; the concept of flavour pairing. This months ingredients are chicken and rose.

I like to keep things rather simple flavourwise so that the flavours are allowed to come forth, the combinations becoming more evident. I've read that risotto is a real challenge, being many a cook's "nightmare". I suppose it's my ignorance that made me try making...

"Approximate-sous-vide" soy sauce marinated chicken breasts with chicken/rose risotto and sweet chilli tomato salsa

The risotto and tomato salsa was based on a modified recipe found at egg.no (English translation). The foodpairing scheme for rose indicates that rose should match well with tomato (strong correlation) and soy sauce (weak correlation), in addition to a weak correlation with chicken. Unfortunately, I couldn't find any asparagus, as this is also indicated to be a good match with rose and might go well with the risotto and chicken. I simply went for green peas and asparagus beans.

Ingredients (four persons)
4 Chicken breast fillets
Soy sauce, sweet + salt

100 ml sweet chilli sauce
2 tomatoes

1 onion, finely chopped
300 ml rice suitable for risotto
1/2 t saffron
2 T white wine vinegar + 50 ml water
1 l chicken stock
3 T butter (had only margarine, unfortunately)
75 ml grated parmesan (actually grana padano)
1 T rose water
basil leaves (garnish)

Directions
The chicken fillets was slashed and left in soy sauce to marinate for 8 hours (two fillets with sweet soy sauce and two in salt). The fillets were put in plastic bags and immersed in a pot with water, cooked "approximately-sous-vide" (65-69 °C) for 2 hours. They were fried quickly just before serving.

The salsa was made simply by chopping tomatoes and mixing with the chilli sauce (didn't bother skinning the tomatoes, since much of the umami flavour sits is in the skin and seeds :).

I won't give a detailed description of how the risotto was made. I simply followed a typical risotto procedure found in most standard cookbooks. The rose water was stirred in at the end of the process. I wanted just a hint of rose, and combining saffron and rose might give a distinctive Persian touch to the risotto. At least, that was the idea, and I didn't want the rose to dominate as it easily will if it's not used with care.

Verdict
I'd say that the chicken vs. rose combination worked well, rather despite than because of the dish as a whole. I felt that several things didn't really work out great:

• the chicken was good but not great, mostly due to the marinating (it'd probably been better plain than marinated, as my son commented)
• the risotto was somewhat on the tart side. I guess I should have spent that extra money on white wine rather than using cheap vinegar (or been lighter on the vinegar). Also, I felt it was a little heavy on parmesan
  

That said, I felt that the rose did not dominate, probably because of the strong parmesan flavour (before adding parmesan, I thought it was heavy on rose, but not afterwards). The rose and chicken blended well together, and still after the meal I could in some way imagine/"visualise" the two flavours lingering together. It's strange, but I can't say the chicken and rose flavour resemble each other, but in some way they're definitely related. However, I really missed the asparagus...

An appropriate Norwegian name for this dish might be "Ros og ris", a phrase for giving feedback/response; "praise & smack".