New journal Flavo(u)r for researchers and practitioners

A new open access journal for issues related to Molecular gastronomy has recently arrived: Flavour. According to the editors, the journal "seeks to create a shared forum for the publication of evidence-based research in an open access context that will make it accessible not only to researchers but also the wider community of chefs, policy makers and the public". This is no small ambition.

The Kitchen Stories project - Interdisciplinary network of culinary claims

The text below is an attempt at drawing up a new programme/collaboration/network for exploring claims about food and cooking. Hereby, we make an effort to start a new international and interdisciplinary network to explore such claims from various angles. If you are a researcher (from any field), teacher at any level, chef or something else and find this interesting, read on and feel free to contact us. The programme is drawn out by researchers from Finland (here and here) and myself.

Update 2nd June 2015: This is also described in a paper in the scientific journal Flavour. Fooladi & Hopia (2013). Culinary precisions as a platform for interdisciplinary dialogue. Flavour, 2(6). (open access)

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

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

Enlightening video lecture on argumentation at Penn State University

Twice a semester Pennsylvania State University holds its Ed Waterbury Lecture on science, technology, mathematics, engineering and mathematics education. This autumn, one of my main sources of inspiration concerning argumentation in science was the invited lecturer.

Prof. Sibel Erduran from University of Bristol is a renown researcher, author and lecturer in fields such as science education, argumentation in science education and philosophy of chemistry. Her contribution to a seminar at the University of Oslo a few years ago was the starting point of my interest in argumentation in science education. In fact, this was the main impulse for me getting involved in what we now call "the Kitchen stories project" (see below).

Her 1 hr lecture + Q/A session at Penn State University was on the topic of argumentation in education (mainly middle school) and professional development of teachers, titled "Modeling Epistemic Practices in Teachers' Learning: The case of argumentation". This lecture is available on the university's web pages (open access, hopefully online for a long time).

Sibel Erduran: "Modeling Epistemic Practices in Teachers' Learning: The case of argumentation"

Food Culture Centre for Children Opened in Oslo

First day of September this year Norway saw a new centre for children's food culture located in an old renaissance farm in the middle of Oslo. This is to be a national resource for helping schools and pre-schools to focus on good food and food culture.

In the Norwegian curriculum the subject home economics ("Food and health") is given throughout primary and lower secondary school. Many would say that this subject does not enjoy much credit of being a "serious" subject in competition with mathematics, language, science etc. There does not even exist school books in this subject for primary school pupils(!) and the subject has not enjoyed the benefits of having its own "national centre for education" to support schools and teachers the same way as many other school subjects (e.g. Norwegian Centre for Science Education).

New chocolate & dispersion article out in Norwegian school science periodical

A popsci article on chocolate truffles/ganache and dispersions recently published in the Norwegian school science periodical (print and web).

As a starting point for the text, I use a recipe for chocolate ganache from the Oslo chocolatier Deux chocolatiers. From there, I describe chocolate and ganache as dispersions and how we can understand the structure/texture of chocolate, why chocolate seizes and where chocolate ganache/truffles come into the picture. The article can be found at www.naturfag.no/mat:

• Norwegian version
• Google translation
• pdf of periodical, Naturfag 2/10

Also, recommendable is Anu's blog molekyyligastronomia with two entries recently on chocolate ganache (look forward to the day comes that google translate deals efficiently with Finnish grammar, though).

To round off the season, Muppet Show's own gastronomical column headed by the Swedish chef making chocolate Moose must be one of the ultimate Christmas treats treat wrap up the fooducation blog before Christmas holidays :)

Some more posts on chocolate

• Previous blog posts at fooducation on chocolate
• Two previous blog posts at fooducation specifically on dispersions

Why are some considered food lovers whereas others are considered food geeks?

Often, when I talk about food I'm met with an attitude that I'm talking chemistry and for that reason whatever I say is incomprehensible. The blinds go down and I see the eyes of the person I talk with go all shifty. Probably, he or she considers me being a food geek...

Whereas "food lover" has mostly positive connotations, "food geek" has this mixed flavour to it. Could it be that the "food geek" (whoever that might be) holds some concepts which he applies in considering the food and which sets him apart from the food lover?

One reason that food geeks are considered as, simply geeks, might perhaps find it's reason in what has by pedagogics researchers Meyers & Land (2003, 2005) been coined "threshold concepts". Take any stereotypical notion of a geek, and you'll probably find that one important reason that you consider him a geek is because he holds some knowledge or a world view that lies beyond your grasp (for simplicity I'll use "he" for the geek, but it could of course be a "she" as well. Likewise, I'll use "you" for the non-geek). This could e.g. be a view coloured by mathematical insight (maths/physics geek) or chemical insight (chemistry geek). Often he sees things using his mathematical or chemical spectacles that you normally would consider everyday matters. Accordingly, for many "food geeks" food is not only food but an assembly of plant/animal cells, molecules or even "chemicals" that can be manipulated. The result is a gap between his way of seeing things and your way of seeing things, in this case food and cooking; he becomes the geek.

Dancing the structure of a molecule + scent vs music revisited

Some time ago I caught a glimpse of a headline about some researchers "dancing their natural science projects", more specifically a biochemist dancing the structure of certain biochemical compounds. I thought the idea was rather far-fetched and didn't give it further thought. After seeing it just recently I find myself being so very wrong... Second part of the post contains a few recent thoughts about a project on scent vs. music.

Have a look at the video below. In the start of the video I didn't see the point, but after a while things started to dawn on me.

Lipids Dance! from Kerstin Wagner on Vimeo.

After watching the video I realised that this did indeed illustrate behaviour of the molecules in question in a very vivid way. I'm of the opinion that one should look for as many possible ways of describing and explaining a phenomenon as possible. If a student tells you they don't understand what you're saying there is seldom any help in repeating the same words one more time. You need to find new words, some other metaphor, another mental representation.

How small are actually the things food is made of?

How small are single plant cells, proteins, sugar molecules? What about those things that spoil our food: bacteria, enzymes? All of them are really small, but when things get this small it is often difficult to grasp that there are huge differences in smallness as well. Below is a tip on how you might get to grips with this.

When dealing with food we talk or read about proteins, carbohydrates, plant cells, enzymes, bacteria and lots of different "really small things". Enzymes react, making fruit brown, proteins and sugars react to give what we perceive as brown coloured and pleasant smelling bread crust. Plant cells absorb or lose water through osmosis to become hydrated or dried, resulting in crunchy or dry/flabby vegetables or fruit. Bacteria and fungi either help us making leavened bread or yogurt, or they spoil our food rendering it unappetizing or even unhealthy.

Usually we talk of these things as macroscopic entities: proteins = eggs, fungi = visible mould on old bread, carbohydrates = sugar in the sugar cup. However, some times these are referred to in terms of their microscopic properties, and this is among the challenges when teaching about food (many of these things are actually submicroscopic, but in educational context we commonly refer to this as the "micro level").

The concept of "smallness"

During my time of teaching, I've realised that many people in general have not reflected on several aspects of this feature:

1. there is indeed a microscopic world behind the macroscopic sensible/tangible world, and the latter is often a reflection of the former (after all, eggs are cooked because protein molecules react in certain ways)
2. there are huge differences in actual size between these things which we commonly just think of as "really small"

"Culinary precisions" and/or "Kitchen stories" at science education conference

Last week, I attended the IOSTE XIV symposium. The topic of my presentation was a follow-up of three previous blogposts on culinary precisions: a framework on teaching "nature of science" (argumentation and inquiry) using culinary precisions.

The biannual conference was hosted by IOSTE, the International Organization for Science and Technology Education. It involved more than 200 participants from 47(?) countries from all continents, located in the beautiful Slovene town of Bled. A true pearl.

BACKGROUND

A year ago I wrote three posts on these matters, and these are the background for an exciting new collaboration with researchers from Finland (links below). The posts were:

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

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

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

"The fun-flavoured way to learn science"

Paulina Mata and her colleagues in Portugal have produced a very interesting booklet on "Experiments for the family to do together" (...in the kitchen).

In a previous post on inquiry-based teaching methods and promoting students' argumentation skills I referred to a European Commission report. In this report, it is referred to two best practice examples, one of them being the project Pollen (EU Sixth Framework Programme 2002-2006). Slightly embarrassed, I must admit not knowing that a part of this was a resource for families to learn experimenting with and through food.

The Portuguese Pollen team together with Paulina Mata have developed the booklet "The fun-flavoured way to learn science - Experiments for the family to do together" in Portuguese and English.

The booklet is written in a very simple language and seems to be aimed at a general public, both children and adults, in order to stimulate adults to experiment more at home together with their children (or vice versa). It starts out with some general comments and recommendations on experimenting at home, and goes on with a number of very simple and straightforward experiments. One might say that many of the experiments are overly simple ("Why does an ice cube float?", "Do vegetables contain water?" etc.). However, I think that such a "low-level" approach might be a very good idea of several reasons:

One major and one minor literature reference on Molecular gastronomy

At last(!) there is a comprehensive and broad focussed review on molecular gastronomy (MG) in the scientific literature. Also, I stumbled over another scientific paper on the same topic from 2007 which has missed my attention until now.

An important (and seminal?) contribution

Martin at khymos has written a short post on the most recent and comprehensive addition to the scientific publications on MG: "Molecular Gastronomy: A New Emerging Scientific Discipline" written by eight(!) researchers in the field, and is open access. What a gift!

Since it was mentioned already in a paper from 2008 (van der Linden, McClements & Ubbink, ref. here), I've been waiting for this paper for at least a year. It is incredibly welcome that others than Hervé This writes about MG in scientific papers, and now we have several contributions with slightly different viewpoints on the same phenomenon.

December issue of school science magazine on food

The last issue of the Norwegian science education magazine "Naturfag" (equivalent to "School science") has several articles on food previously posted here on fooducation. The magazine is in Norwegian and free for download.

Issue 2/2009 with mostly Christmas- and winter related content includes the following articles based on fooducation posts. Most of them are updated/revised versions and are also found as updated versions on the Norwegian Centre for Science Education "gastronomic school science" web pages www.naturfag.no/mat (Google translation here):

1. "Christmas dinner trimmings - a hot potato?" (part 1 and part 2) and "Green vegetables and chlorophyll revisited" combined
   
   
2. "Deciphering an old preserves recipe"
   
   
3. The effect of added sugar, salt and high temperature on microorganisms/yeast. This is not previously published on fooducation, but a time lapse video with captions in Norwegian can be seen on YouTube. It is self-explanatory, i guess. The purpose is to show an easy to set up experiment for testing conditions under which microorganisms thrive or die. Relevance is to baking (you want to promote the yeast) and preservation (you want to suppress or kill microorganisms)
   
   
4. "Leavens in cookies - theory and practice"

The latter also made it into the news section of "Nysgjerrigper", a science knowledge project from the Norwegian Research Council.

Of course there are several other interesting topics in the issue as well, such as "Gingerbread house architecture" "Catch sight of and predict the northern light" and more.

Merry Christmas

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 1:3 - why it seizes with just a little water, ...and what to do about it

Revised June 2nd 2015 

(Important: See the last set of comments for a critique which possibly requires some major revision to the text and figures).

If just a little amount of water finds its way into melting chocolate, it goes all grainy and solid - it seizes/curdles. There is really no fix to the problem. However, if some more water is added, the chocolate suddenly becomes fluid again. How come?

In three recent posts in the Swedish food blog Matmolekyler ("Food molecules"), Malin discusses the physics of chocolate. In the third one, the question arose on what really happens when a little water makes the chocolate go all grainy, and why adding some more water solves the problem. It made me start looking around in my "standard" food literature base: Corriher, McGee, Belitz/Grosch/Shieberle, Barham, Pedersen, Dahlgren. Although Corriher came closest, none of them had the answer to Malin's question: "is there an oil-in-water emulsion going on or something?". Finally, Beckett did have the answer, maybe not very surprising, since the name of the book is "The Science of Chocolate". However, it took some serious searching even in this book in addition to a few research papers. Hence, I expect to write a couple of more posts on chocolate since I've dug into the topic.

Chocolate seems like no easy medium to work with, and according to books on the topic I have to follow loads of specific directions in order to avoid failing. I've postponed it in fear of failing. The solution to the problem: start by failing on purpose!

The problem
It all starts when trying to melt the chocolate. (Cook)books say:

1. the chocolate should be carved or cut into small pieces
2. use low heat, preferably a water bath or double boiler , stirring continuously
3. don't ever get water in the chocolate (either from the water bath or from moist equipment)
4. (microwave oven might be used as an alternative, although carefully)

I have an inherent need of doing things as easy as possible, and using the double boiler method makes me go nuts waiting for the last bits to melt. To me, water bath equals splashing warm tap water around in the kitchen sink. In that respect, points 2-3 pose a problem, because getting water in the chocolate results in this:

Left: 100 g melted pure (55%) chocolate
Right: the same melted chocolate after adding less than a teaspoon of water

In fact, so little water is needed for this to happen that steam from a boiling pan might be enough to make the chocolate go grainy. When this happens, there is no way back to the pure chocolate. However, it is perfectly usable for other purposes such as chocolate sauce, ganache, drinking cocoa etc. Alternatives to using water bath or a double boiler principle. In stead of water bath or double boiler, I usually use the microwave or even melt the chocolate directly in the pot using low heat and stirring continuously (have to be very careful). However, I love sabotage experiments. When recipes tell me by all means not to do something, the little boy awakens and I go for it. And that's the point in this post: what happens when chocolate seizes?

To understand what happens one need to know what chocolate is...

Basically, chocolate is

• cocoa fat (cocoa butter) - water repelling
• sugar particles - water loving
• cocoa particles - somewhat unclear*
• lecithin emulsifier - water repelling and water loving
• (for milk chocolate: milk fat and/or milk powder)

Chocolate is a dispersion, consisting of solids distributed in a fatty (continuous) phase. It contains miniscule cocoa particles (mean diameter ca. 0.016 mm) and sugar particles too small for our tongue to notice them as grainy when properly distributed. The sugar is hydrophilic (water loving), and repelled by the fat. An important function of the lecithin emulsifier is to build protecting layers around the sugar particles so that they don't separate from the fatty phase and give a grainy texture. The emulsifier is commonly lecithin (lecithin is also a natural constituent of egg yolk, and the main reason for why the yolk doesn't split into a fatty and a watery phase).

Schematic drawing of the above photos
Left: pure chocolate. Right: chocolate after adding just a little water

What happens when water gets into the chocolate?
In it's solid form, pure chocolate is a relatively stable system virtually free of water (0.5-1.5% by weight). When the chocolate is melted, the stable dispersion is challenged. If just a small amount of water (or steam) finds its way into the chocolate, the water molecules form droplets, since they don't want to mingle with the fat. Since water and sugar like to mingle, the sugar particles are wetted by the water. The result is "the sugar bowl effect", just as when a few drops of water are spilled into a sugar bowl. The tiny sugar particles in the chocolate become moist and cling together giving larger lumps (agglomerates). The result is an inhomogeneous mixture between these sugar agglomerates and the cocoa fat mixture. These won't mix evenly because the sugar has gone watery (the lecithin is probably not capable of stabilising such large amounts of hydrophilic constituents). Since sugar is a major ingredient in chocolate, it all goes grainy. A water content of 3-4% by weight is enough to make the chocolate seize. Since the chocolate might contain som water already the critical amount of added water might be as low as 1.5% by weight (1/3 teaspoon on 100 g, ref. Afoakwa et al.).

Add some more water, and everything is "fine" again
If the chocolate has seized, there is really no way back to the original chocolate. However, if some more water is added, the grainy mass magically turns silky smooth again. What happens is that the emulsion inverts; whereas fat was the continuous phase in chocolate, now water is the continuous phase and the fat is distributed/"dissolved" in the water:

Left: 100 g melted pure (55%) chocolate, seized with less than a teaspoon water

Right: the same chocolate after a tablespoon of water

A definite explanation of this was in fact rather difficult to find, and the only literature source stating this explicitly was in fact Beckett's book (The Science of Chocolate. Afoakwe also states this, but refers to Beckett's book). He writes that about 20% by weight water vs. chocolate is needed to achieve such a phase inversion, whereas Corriher writes that you need a minimum of 1 tablespoon water per 56 g (2 oz) chocolate. This roughly equals 30% 20% by weight. Note that this is total amount of water; if cream, butter or some other water-containing ingredient is used, this contribution counts.

Schematic drawing of the above photos

Left: seized chocolate. Right: after adding a tablespoon of water

Since chocolate contain plenty of emulsifiers, this emulsion might be quite stable and a good starting point to many wondrous things such as drinking cocoa, chocolate sauce, ganache/truffles, foam/mousse ("chocolate chantilly") or even a chocolate mayonnaise.

What might be taught/learned

• dispersions: emulsions and solid dispersions
• solutions/solubility, hydrophilic and hydrophobic properties
• experimental and cooking skills (dealing with chocolate)
• observational skills (what to look for in an experiment)

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*Note: Some sources (Rowat et al., 2011, and these ppt slides by Naveen Sinha) state that the cocoa particles are hydrophilic (water loving) and that the emulsifier surrounds these rather than (or just as much) as the sugar particles. I have not been able to confirm this and have thus drawn it as neither water loving or water repelling. However, I've found a couple of papers stating that the cocoa particles in fact contain fat (points towards water repelling, see Do et al., 2011) and that the emulsifier primarily attaches itself to the sugar particles (Vernier cited in Svanberg et al., 2011).

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References, scientific papers

Afoakwa, Paterson & Fowler: "Factors influencing rheological and textural qualities in chocolate - a review". Trends Food Sci. Tech., 2007, 290-298.
Do, Vieira, Hargreaves, Mitchell & Wolf: "Structural characteristics of cocoa particles and their effect on the viscosity of reduced fat chocolate". LWT - Food Sci. Tech., 2011, 44, 1207-1211.
Rowat, Hollar, Stone & Rosenberg: "The Science of Chocolate: Interactive Activities on Phase Transitions, Emulsification, and Nucleation". J. Chem. Ed., 2011, 88, 29-33
Svanberg, Ahrné, Lorén & Windhab: "Effect of sugar, cocoa particles and lecithin on cocoa butter crystallisation in seeded and non-seeded chocolate model systems". J. Food Eng., 2011, 104, 70-80.

References, books with relevant information on the subject

Beckett: The Science of Chocolate (1. ed.). Cambridge : Royal Society of Chemistry 2000.
Belitz, Grosch & Schieberle: Food Chemistry (3. ed.). Berlin: Springer 2004.
Dahlgren, Ö.: Laga mat - hur man gör och varför. Stockholm : Liber utbildning, 1994.
McGee, H.: McGee on Food and Cooking. London: Hodder and Stoughton 2004.
Corriher, S.: Cookwise. New York: William Morrow 1997.
Pedersen, T.: Kemien bag gastronomien. Copenhagen: Nyt Nordisk Forlag 2005.

My first spherification

Yes, I know. I'm six years late to be among the cool guys, but who cares? To me it's all about having fun and learning, and then being late is no issue.

As far as I know, spherification and it's related methods were introduced by El Bulli chef Ferran Adrià et al. some time after the turn of century. I has got a lot of attention, and a You Tube search on the term gives quite a few hits on demonstrations of DIY spherification.

The phenomenon is based on using hydrocolloids, that is compounds that can generate gels, mostly with water but other media are also know (oils and alcohol mixtures, that is). A good place to start is Martin Lersch's hydrocolloid recipe collection "Texture". A number of different gelling agents are being used, the most common household substances being gelatin and fruit pectin, the latter often used when making jams and jellies.

In this case I got my hands on some sodium alginate that I wanted to play with. When a mixture containing sodium alginate comes in contact with a calcium solution, the alginate starts to cross-link and a gel is formed. In this case, dripping a alginate-containing solution into calcium chloride generates small beads that are gelatinous on the surface and liquid in the centre. Alginate is somewhat sensitive to the pH, and sodium citrate might be used as a buffer to stabilise the pH at ca. 4-5 (all this information is found in the Textures recipe collection).

Sodium alginate is a polymeric carbohydrate-like compound which is soluble in water. When it reacts with calcium ions, cross-links are formed giving large three dimensional webs that become viscous/gel-like and holds water.


Strawberry spheres in sparkling drink (for lava lamp effect)
(Sparkling Chardonnay or non alcoholic cider are both fine)

Equipment
(immersion) blender
scale (0.1 g precision is needed)
some general kitchenware
disposable plastic pipette (7 ml) or plastic syringe (10-20 ml)
(pH strips)

Ingredients
frozen and thawed strawberries, 200 g
sugar, 25 g
sodium alginate, 1.9 g
sodium citrate¹, 2 g
calcium chloride², 2.5-4 g
water, 500 ml
Sparkling Chardonnay or non-alcoholic drink (i.e. apple cider)

Procedure (see You Tube for informative demonstrations)
For template, the recipe for Melon cantaloupe caviar taken from El Bulli's texturas recipes: The strawberries were blended and mixed with the sugar. pH measured to be ca. 3 (somewhat uncertain since the berries gave some colour to the strips). Sodium citrate was added gradually, stopping at a total of 2 g to get a pH of ca. 4-5.¹ Sodium alginate was added and blended (the alginate partially turned into lumps; should have added the alginate to a small portion, mixed this, and then added the rest. Lots of blending did the trick). The mixture was strained through a sieve. For easier dripping (see below), the mixture was diluted 1:1 with water (the initial strawberry mixture was rather viscous, resulting in oblong or drop-shaped "caviars"). This would of course affect gelation, hence the amounts here are deduced on a try-and-fail basis.

Calcium chloride was dissolved in the water. The strawberry mixture was dripped into the calcium chloride solution, the drops forming small strawberry beads, and left for 1/2 to 1 minute.³ The beads were strained, rinsed in water and added to the sparkling wine or cider.

(Tri)sodium citrate functions as a buffer due to its three carboxylic acid functional groups.


Verdict
The strawberry beads/spheres/caviars tasted good, no detectable flavour from the matrix. Simply strawberry. While mixing, the strawberries turned somewhat greyish. Not surprising, since the colour is an anthocyanin pigment (anthocyanin colours are pH dependent, often bright red in acidic environment and more on the green/blue side in basic conditions).

The reason for using Chardonnay was simply that I found Chardonnay to match well with strawberries at the food pairing database, and that this might be a fun aperitif (although I would maybe not spend money on an expensive wine and then put strawberry in it).

What might be taught

• chemical reactions might occur between chemical compounds
• experimental and cooking skills (weighing exact amounts, diluting etc.)
• dispersions: gels (hydrocolloids) and macromolecules
• pH, acidity and buffers (citrate)
• density (the beads float up together with the CO₂ bubbles, and sink when the bubbles burst)

The procedure is somewhat complicated, and I'm glad I didn't bring the kids the first time. When the table was set, and the solutions were ready, the kids loved dripping the solution making beads. Now I've got some experience, and next time I'll bring them along from the beginning.

Notes/comments
¹ It was difficult to assess the pH correctly, and the amounts of sodium citrate suggested in the textures recipe collection did not (seemingly) have the desired effect. Hence, citrate was added until the desired pH, adding up to 2 g.

² The CaCl₂ must be dry/dehydrated. In my case, it had absorbed moisture from the air and gone all wet (quite hygroscopic). It was in left in shallow bowls in the oven at 150-200 °C stirring occasionally. A couple of hours later, a white crystalline/powdery salt was left.

³ Using 2.5 g CaCl₂ per 500 ml water and leaving the beads 30 seconds in the bath resulted in rather soft beads. Leaving them for one minute gave beads that were solid almost throughout. I wanted firmer beads with a soft interior. Increasing the concentration to 4 g CaCl₂ per 500 ml water did the trick: firm shell, and liquid interior when the beads were left in the bath for somewhat less than a minute.

References
McGee, H.: McGee on Food and Cooking. London: Hodder and Stoughton 2004.
Lersch, M.: Hydrocolloid recipe collection

Has the term "Molecular gastronomy" lost it's content?

The term Molecular gastronomy has been debated quite heavily the few last years, and several prominent chefs and writers have denounced the term. What's in a name?

An interesting post on the development and applications of molecular gastronomy (MG), both as a term, but also as a phenomenon at Martin's khymos. Most of the relevant links are found in that post as well. Also, many of the comments are relevant and interesting, making the post more complete.

Has MG reached a point of matureness in the sense that it might have some real impact on peoples cooking in general? As mentioned in Martin's post, it has already to a certain extent, such as sous-vide cooking. However, some of the more spectacular applications (foams, alginate spheres etc.) combined with misuse of the term in media has resulted in the term being discredited. In my opinion, the name is not the main thing (although its ok to avoid misunderstandings and establish a common ground languagewise as well). I'll continue using the term until a better alternative gets the main foothold.

"Iberico on window pane". Photo: Naturlegvis/Erlend Krumsvik

However, I'd be somewhat surprised if we don't see more of the results from MG/research reaching a general public soon. Hopefully, some of the "less spectacular" but more "relevant" or "useful" knowledge might hit the domestic kitchens in not too long. The real test for me is: is this knowledge so relevant to the everyday citizen that I should teach this to my preservice teacher students attending our Food & health courses? A few examples from the top of my head:

• Alginate/hydrocolloid spheres (specifically)? No
• Sous vide cooking? Yes if the focus lies on the method rather than specialty equipment
• Application of knowledge about maillard reactions? Yes/probably
  
• Application of knowledge about umami taste? Probably
• Dispersions in food and everyday life (two posts)? Yes
  

Among the more recent and interesting examples is the 2007 Mottram et al. (incl. Heston Blumenthal) article on tomato pulp being more rich on umami taste than the flesh (short RSC chemistryworld article free of charge). When dealing with tomatoes, many cookbooks and recipes tell you to remove the pulp and use the flesh of the tomato only. However, Mottram's results indicate that the pulp and seeds carry lots of wonderful umami taste, and hence it'd be a shame to throw that away. Heston Blumenthal demonstrates this in one of his BBC In search of perfection episodes, more specifically making tomato sauce in "The perfect hamburger" episode. Also, tomato sauce figures among the freely available Blumenthal BBC videos.

Many cookbook recipes might be rewritten just slightly to incorporate this knowledge, giving more flavourful dishes. Furthermore, this knowledge is something that the domestic cook might adopt rather easily. I'd be really happy to see something like this making it into the domestic kitchens around. In that case, MG (or whatever one prefers to call it) does indeed have had an impact.

References (not comprehensive)
Ubbink, J. et al.: "Molecular gastronomy: a food fad or science supporting innovative cuisine?", Trends in Food Science & Technology, 2008, 19, 372-382

Ubbink, J. et al.: "Molecular Gastronomy: A Food Fad or an Interface for Science-based Cooking?", Food Biophysics, 2008, 3, 1557-1866

Martin Lersch (khymos) on definitions of Molecular gastronomy

Kroger, M: "Editorial: What's All This We Hear about Molecular Gastronomy?", Comprehensive Reviews in Food Science and Food Safety, 2006, 5, 48 - 50.

This, H. :"Molecular gastronomy", Angewandte Chemie, 2002, 41, 83-88.

Very easy odour adaptation experiment

Matmolekyler published last month an incredibly easy and straightforward experiment for illustrating the phenomenon of odour adaptation.

Adaptation is the phenomenon in which you stop noticing an odour/aroma when you've been subjected to it for a while. This is, amongst other, used as a motive for varying aroma components throughout a meal. Have a look at "Jullovsexperiment: Hacka ditt luktsinne" (Google translated version: "Christmas holiday experiment: Hack your sense of smell"). In this case, Malin Sandström, proposes to use coffee and cinnamon.

I'm on constant search for experiments that give personal experiences with food and science. In my eyes, the sheer ease of this experiment is maybe the greatest advantage, making it very acessable for anyone wanting to experiment with these phenomena.

Heston Blumenthal and Peter Barham have also described this in one of their Kitchen Chemistry episodes (Discovery channel):

"Our brains, it seems, respond much more to changes in which molecules are in the nose and mouth than they do to what is actually there, for example - if you chew a piece of gum, the flavour will disappear after a few minutes, as your brain gets "bored" by the aroma in the nose - but there is virtually no reduction in the amount of flavour molecules in the nose. However, if you simply change the input from your tongue, by, for example - taking a sip of sweetened water - the full flavour will be instantly restored"

Peter Barham (Discovery Channel)

What to teach/learn

• Gain experience with aroma and sense of smell
• Experience the phenomenon of adaptation
• (Experience that flavour experience is both taste and aroma)

Post-comment
I tested the experiment with our students and it worked perfectly! The student with the cinnamon even commented: "the odour fades away while I'm smelling it". Great fun. A colleague has been doing this experiment for several years using (synthetic) almond and rum essences. However, the intensities of these are somewhat uneven, and one swamps the other. Coffee and cinnamon works perfectly :)