In 2009 I wrote about my journey towards the perfect soft boiled eggs. Equipped with a formula I knew what I wanted, but it wasn’t so easy after all. Since then I’ve tried to model experimental data from Douglas Baldwin as well as data from my own measurements of egg yolk tempereatures when cooked sous vide (pictures of how I did this at the end of this blog post). I never got around to blog about the results, and now there’s no need for it anymore: The egg yolk problem has been solved! And the question that remains is: How we can utilize this in the kitchen?

The break through came this year with a paper by César Vega and Ruben Mercadé-Prieto entiteld Culinary Biophysics: on the Nature of the 6X°C Egg [1]. In my opinion it’s a brilliant example of molecular gastronomy: the results are practical enough for chefs and technical enough for scientists. This paper holds the key to unlock the true potential of egg yolk texture, and with it every chef can reproducibly prepare yolks with textures in the whole range between soft and hard. If you think I sound a bit exalted, you’re absolutely right.

Eggs cooked at low temperature have been all around the internet for the last couple of years, but a general feature of all these posts has been a focus on temperature. This has been the generally accepted truth. Even Hervé This in an interview with Discover magazine claimed that “Cooking eggs is really a question of temperature, not time”. But the present paper counters this. It’s main conclusion is that the texture of the egg yolk is a result of the time-temperature combination used, it’s thermal history if you like. If you’re interested in the details of the paper I suggest you jump directly to the pdf (I could download it for free some days ago, so give it a try), but if you’re only interested in the results, read on! A practical way to measure egg yolk texture is by using a rheometer. It’s a fancy piece of equipment that measures viscosity (and for those of you who are technically inclined – it measures viscosity as a function of shear rate). And what César and Ruben have done is to prepare a graph that shows the viscosity of a large number of temperature and time combinations. It’s a so-called iso-viscosity plot, meaning that once you have decided which viscosity you want the graph will show you all the temperature-time combinations that will give the desired result.

The figure shows how an egg yolk with a texture resembling one of the reference foods can be prepared by chosing any temperature-time combination along the respective plotted lines. (The figure is used with kind permission from Springer Science+Business Media: César Vega and Ruben Mercadé-Prieto in Food Biophysics 2011, 6:152-159, Culinary Biophysics: on the Nature of the 6X °C Egg, figure 8, page 158. The legend overlay has been added by me for clarity.)

For chefs, and even for chemists not working with rheology, it’s difficult to relate to numerical values of viscosity. To get around this the authors did a clever thing by measuring the viscosity of a range of semi-solid foods that may function as reference points: sweetened condensed milk, mayonnaise, honey, cookie icing and Marmite. You can use the iso-viscosity plot shown above to find different time-temperature combinations that give the same yolk viscosity. To use the plot, first decide which texture you want the egg yolk to have. Let’s say you’re in for a honey like texture (filled triangles). Pick a temperature, draw a vertical line until it crosses the line plotted through the triangles and then a horizontal line from there to the time axis. Repeating the exercise for different temperatures will give the different time-temperature combinations that all give a honey like yolk texture; in this case 310 min at 60 °C, 200 min at 61 °C, 125 min at 62 °C, 75 min at 63 °C, 55 min at 64 °C, 45 at 65 °C, 40 min at 66 °C, 26 min at 67 °C and finally 25 min at 68 °C will all do the trick. With a temperature controlled water bath one can chose whatever combination one likes, but if using a large pot of water and manually turning the heat on/off it’s advisable to cook the egg yolk in the lower temperature range. Also, the authors state that it requires a bit of practice to obtain different textures at temperatures above 66 °C.

The paper only deals with egg yolks. At the given time-temperature combinations the white will remain more or less runny. If only the yolk is to be used this doesn’t matter. But if serving the whole egg a simple way to set the egg white is to immerse the egg in boiling water for 2-3 minutes. Alternatively for a little longer at 85 or 90 °C. A comment made by Olly Rouse to my previous post on eggs suggests 8 min at 90 °C followed by cooling at 55 °C is perfect to set the white. However, if the eggs are to be “cooled” at 6X °C maybe 6-7 min is enough. What complicates matters even more is that at 6X °C convection inside the still runny egg white contributes significantly to the heat transfer, but I assume that this is negligible in combination with the longer cooking times in the lower 6X °C range.

Now that all possible egg yolk textures are available the question is: How we can utilize this in the kitchen? Apart from preparing soft boiled eggs, are there any applications in cooking? I’m sure there are many good ideas out there just waiting to be realized. If you blog or twitter about your ideas for utilizing precisely cooked egg yolks I suggest that you tag your blogposts with 6Xyolk and your tweets with #6Xyolk. Then everyone can easily follow up on the progress.

From my own experiments with measuring the core temperature of eggs cooked sous vide: The pictures show how I cut a thin slice from a plastic wine cork, pierced it with a philips screw driver, glued it to an egg, carefully pierced the egg shell with the same screw driver and finally introduced a thermocouple into the core of the egg yolk. There was enough friction between the thermocouple and the wine cork to allow the egg to be suspended by the thermocouple in the water bath. Temperature was logged using myPClab from Novus. Prior to the measurement the egg with the inserted thermocouple were left for several hours in the fridge for temperature equillibration.

[1] Vega, C.; Mercadé-Prieto, R. Food Biophysics 2011, 152-159. DOI: 10.1007/s11483-010-9200-1

• Culinary innovation
• Blurring lines between food technology and culinary arts
• Issues and trends related to human nutrition
• The collaboration between food science and culinary innovation
• Techniques and technology and their role in quality of life/guest satisfaction associated with culinary, wine and food experiences
• Trends in molecular gastronomy and its derivates
• Annual review of trends in culinary science and technology
• Applied research
• Relevant research notes
• Management styles, methods and principles
• Techniques and innovations

While you wait for Flavour and International Journal of Gastronomy and Food Science to appear you can always browse through some back issues of this journal.

According to the journal home page the main areas of interest include:

• Mechanisms of taste and flavour
• How flavour affects liking and satisfaction gained from eating
• Relationships between satiety and perceived quality of foods
• Choice behaviour with respect to food quality and satiety
• Multi-modal integration and multi-sensory perception of flavour
• How all senses play their role in our perception of flavour both in combination and separately
• How ingredients are changed by different cooking methods and in the mouth
• Aroma release mechanisms in the mouth
• Interoception
• The evolution of our organs of taste
• The psychology and neuroscience of food preferences and habit formation

I just received an alert today about a major review article on molecular gastronomy: Molecular Gastronomy: A New Emerging Scientific Discipline (DOI: 10.1021/cr900105w) is a British-Danish joint publication by Peter Barham, Leif H. Skibsted, Wender L. P. Bredie, Michael Bom Frøst, Per Møller, Jens Risbo, Pia Snitkjær, and Louise Mørch Mortensen. Peter Barham is a professor in polymer physics at the University of Bristol, author of The science of cooking and probably doesn’t need further introduction. The Danes are all associated with the Department of Food Science at the University of Copenhagen and have a varied background in chemistry, food science, sensory science and psychology background. Check out the links to their individual profiles more info on projects and publications. Leif H. Skibsted and Michael Bom Frøst head several molecular gastronomy related projects. The Danish scientists also work closely together with Claus Meyer, chef at Meyers madhus and visiting professor at Copenhagen University, and Torsten Vildgaard, assistant head chef at Denmark’s gastronomic shining star Noma (which Claus Meyer started together with René Redzepi in 2004 – they were ranked 3rd in Restaurant magazines top 50 list for 2009, only surpassed by el Bulli and The Fat Duck).

Considering the impact factor of Chemical Reviews (ranked as a clear no. 1 among chemistry journals), this review will likely remain the review on molecular gastronomy for years to come – so you can just as well go ahead and read it. It’s got a whopping 53 pages and more than 350 references, and will be very useful for further studies and research. Oh, and the authors have opted for sponsored access, meaning that you can download the whole review for free!

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Some curiosa as a post scriptum: Even though the above mentioned review is the most comprehensive academic treatment on molecular gastronomy to this date, the very first mention of “molecular gastronomy” in Chemical Reviews was in a review on platinum chemistry in 2005 (check out the full text search). When writing a review on platinum C-H activation chemistry some years ago with my supervisor I mentioned in the short author bio that besides my research activities I had “a strong interest in molecular gastronomy”. My supervisor prof. Mats Tilset then added to his bio that he had “a strong interest in practical gastronomy”. Even in serious journals there is room for a little fun

A while ago I came across the article “Christmas gingerbread (Lebkuchen) and Christmas cheer–review of the potential role of mood elevating amphetamine-like compounds formed in vivo and in furno” (abstract from NCBI, free full text pdf download from publisher). The paper reviews a hypothesis proposed by Alexander Shulgin in a series of papers appearing in Nature in the 60′s. Shulgin noted that allylbenzenes and propenylbenzens found in many spices are “merely lacking ammonia to become amphetamines”. The author reviews the evidence that such substances may be converted in the body to psychoactive metabolites, but concludes that the evidence is equivocal at best. However, the author launches an alternative theory:

“… the formation of these compounds during the cooking process, what I have called “in furno.” Examination of the Lebkuchen recipe in Table 3 reveals chemical constituents that, when heated together in furno might plausibly result in some ammonia addition to the alkenylbenzene double bonds, which would lead to the presence in the Lebkuchen of 4-methoxyamphetamine (PMA) from (E)-anethole and 4-hydroxy-3-methoxyamphetamine (HMA) from eugenol.”

But as the author prudently add: “Until the appropriate laboratory and clinical investigations are performed, it is merely a subject of speculation and fantasy.” Nevertheless is an entertaining paper to read, and I’m sure that this kind of “science triva” can cheer up discussions around the dinner tables in an otherwise dark December. And I must add that I really love the term in furno (i.e. in the oven, during the cooking/baking process) used alongside the more common in vivo and in vitro.

I’ve illustrated the proposed reactions in the scheme below. Anethole and eugenol are found in cloves/cinnamon and anise seeds respectively. Baker’s ammonia is known to chemists as ammonium carbonate, but also under names such as salt of hartshorn. It has a very strong smell of ammonia and upon heating it decomposes and releases ammonia which could possibly react with the allyl/propenyl groups.

[Found via the very funny NCBI ROFL blog]

After 7 days of feeding my sour dough starter “took off” and was ready for baking. Even with a water bath set to 28 °C it took longer than expected. I started off with 100% hydration as this is convenient when you have to feed your starter frequently. Using only whole grain rye flour and water, I fed my starter every 12 hours (I’ve included details of the “feeding schedule” at the end of this post). This time interval is based on the growth cycle of yeast, where the yeast after an exponential growth phase reaches a plateau after 8-12 hours. This is the best time for feeding the starter.

There seems to be a consensus that a wet starter (i.e. 100% hydration) favors growth of lactic acid bacteria (LAB) which in turn produce acids. The low pH after 2 days in my starter suggests plenty of LAB activity, so the main challenge for me was to get the yeast growing. Considering the fact that the yeasts found in sourdoughs prefer areob conditions for growth, I should have whisked in more air with each addition of water. And I wonder if this is the origin of the widespread myth that you “catch wild yeasts from the air”. I’m quite sure whisking helps, but what you do is not to catch yeast, but rather feed oxygen to your starter. This needs testing though! Most starter recipes call for discarding of half or even more of the starter before each feeding. Even though it seems wasteful I wonder if an important effect of this is to dilute the acid produced by the LAB (the flour may also act as a buffer). This acid will to some extent slow the growth of yeasts (even though the sourdough yeasts are far more acid tolerant than the conventional brewer/baker’s yeast Saccharomyces cerevisia).

Bubbles indicating that the starter is active

Regarding temperature the growth optimum for LAB lies around 32-33 °C whereas the growth optimum for yeast is somewhat lower at 28 °C. The sourdough FAQ has further temperature recommendations which are illustarted in the graph below (data from sourdough FAQ). Holding this together with the notion (see for instance p. 272 in “The handbook of dough fermentations”) that lower temperatures (20-25 °C) favor acetic acid production (= stronger flavor) and higher temperature (> 32 °C) favors lactic acid production (= milder flavor) it immediately becomes clear why a starter kept at roomtemperature has little yeast activity and smells of acetic acid. It need not be ruined, but is desperately in need of dilution, aeration and higher temperature.

Effect of temperature on growth of lactic acid bacteria and yeast based on data for optimum growth and no growth from the sourdough FAQ

I’ve kept the starter alive since August and baked with it at least once a week. I make sure that I keep 50-100 g which I store in the fridge. I’ve also frozen a sample just in case. I’ve changed from 100% hydration to 67% hydration, as this simplifies the calculations a little. On the evening before baking day I feed the starter to a total starter weight of approximately 900 g. The next day I bake bread as follows (the exact numbers were calculated using an internet sour dough calculator with the following input: 3200 g total dough weight, 25% starter, 67% hydration of starter and final dough and 1.8% salt):

Sour dough bread
949 g water
1417 g flour *
800 g starter (67% hydration, 25% of total dough)
34 g salt

* for instance 300 g rye whole grain, 200 g rye fine, 300 g whole grain wheat and then plain all-purpose wheat flour up to 1417 g.

Mix water and flour mixed until all flour is wetted. Leave for 15-20 minutes (during which the autolyse proceeds – this eases subsequent mixing). Mix (see more comments below regarding method/machine for this) until dough is smooth, and while mixer is running add sour dough starter. Once the starter has been properly incorporated into the dough, add the salt. Cover and leave to rise until volume has increased 30-100% (I know – this is not very accurate…). I have left it in on my bench top, but while this worked well on warm August days, it seems to be less than ideal on colder October days. Leaving the dough to rise on top of the fridge might be a conventient compromise here as my current waterbath is not large enough to hold the mixing bowl with dough. The reason I use a starter with a 67% hydration is that I can be more sloppy when adding the starter to the sourdough as it will not change the hydration of the dough. After proofing and slashing I bake the breads on a baking stone which is preheated to 250 °C. Right beneath the baking stone I have a small oven proof dish that I fill with boiling water. This helps to moisten the air in the oven and it simulates the steam injection port of professional baking ovens. There are several reasons why this is important. Moist air is a better heat conductor than dry air, and it prevents the surface from drying out too early while baking, resulting in a better oven spring. Furthermore the moist air condenses on the cold surface of the dough which improves gelatinization of the starch. This in turn gives better crust formation. After 10 min at 250 °C I open the oven to let the moisture out, take out the dish with water, turn the heat down to 220 °C and close the oven door. I bake the breads to a core temperature of about 93-95 °C.

Here I bake two 800 g loaves on a baking stone. Notice the dish with water for steam generation.

I should comment on mixing. When kneading by hand I’ve had a tendency to add to much flour. In fact I think this is one of the reasons why I quit baking bread several years ago – I found that the breads I made generally were a little to dry with a poor crumb, and at that time I didn’t really sit down and think about these matters. In retrospect however there’s no doubt that baking bread and adding flour ad lib until the dough feels good to touch is NOT recommended. Well anayway not unless you stop adding flour while the dough is still quite sticky. The thing about doughs with a high percentage rye is that they are quite sticky, and they should be. This is the best argument you’ll ever get for buying a kitchen gadget: bread doughs are too sticky to be kneaded by hand! There you have it! I’ve settled with the Assistent from Sweden. It was formerly sold under the Electrolux brand, but is now marketed indepentendly, yet it is still produced at the very same factory as always. In the US the machine is known as the Magic Mill. It has a huge 7 L bowl that rotates. The roller is attached to a flexible arm, so if the dough is to hard to work the arm just moves to the middle of the bowl. This significantly reduces the chances of overheating the motor. There are of course other alternatives from Kitchen Aid, Hamilton Beach and Viking Range which seem robust, but I have no experience with these. However, I doubt that the average Kenwood can cope with more than 3 kg of bread dough (but please correct me if I’m wrong ).

Unlike most other machines, the bowl of the Magic Mill/Assitent rotates while the roller pushes the dough to the sides of the bowl

Sources for further reading

I’ve read quite a bit about sourdoughs, and what I’ve been looking for a simple correlation between temperature, hydration and fermentation time. An excellent source of information with lots of practical advice is the FAQ from rec.food.sourdough.

I think the best resource I’ve found sofar is Lorenz and Bruemmer’s chapter “Preferments and Sourdoughs for German Breads” and Teija-Tuula Valjakka, Heikki Kerojoki and Kati Katina’s chapter “Sourdough Bread in Finland and Eastern Europe” in “The handbook of dough fermentations”. I will have to study these more carefuly.

There are quite a number of academic publications which also touch upon the effect of temperature on acid development. Here are some snippets:

“Controlled production of acetic acid in wheat sour doughs”:

…temperature has no significant effect, and that fructose is more efficient in influencing the FQ than dough yield.

FQ = fermentation quotient = lactic acid / acetic acid

“Volatile compound and organic acid productions by mixed wheat sour dough starters: Influence of fermentation parameters and dynamics during baking”:

… Low temperature (25 degrees C) and sour dough firmness (dough yield 135) were appropriate for LAB souring activities but limited yeast metabolism. Raising the temperature to 30 degrees C and semi-fluid sour doughs gave more complete volatile profiles …

“Sourdough: a tool for the improved flavour, texture and shelf-life of wheat bread” (Ph.D. thesis of Kati Katina):

The production of acids depends also on other things such as fermentation temperature, time and dough yield. Optimum temperatures for the growth of lactobacilli are 30-40 °C depending on strain (Stanier et al. 1987) and for yeasts 25-27 °C. In general, a higher temperature, a higher water content of sourdough and the utilisation of wholemeal flour enhances the production of acids in wheat sourdoughs (Brummer and Lorenz 1991, Lorenz and Brummer 2003).

I must admit that I’m a little confused as some of these snippets seem to contradict. It might be that I’m overlooking something important though and that I’m taking results out of their context. Any insight from my readers on this will be greatly appreciated!

Starter details
Here’s the details from my notebook on how I fed my sourdough starter. As I mentioned above, I wonder if discarding dough in the process actually does make sense after all.

• July 29, evening: 50 g rye + 50 g water
• July 30, morning: 25 g rye + 25 g water, evening: small bubbles (!), 50 g rye + 50 g water
• July 31, morning: 50 g rye + 50 g water, evening: pH measured to 3-4 with strips, fed with 50 g rye + 50 g water
• August 1: morning: 50 g rye + 50 g water, tested for bread baking, result: not active enough, feeding continued evening: 50 g rye + 50 g water
• August 2: morning: 50 g rye + 50 g water, evening 50 g rye + 50 g water
• August 3: morning: 50 g rye + 50 g water, evening: no bubbles, discarded all except ~100 g, fed with 50 g rye + 50 g water
• August 4: morning: 50 g rye + 50 g water, evening 50 g rye + 50 g water
• August 5: morning: 50 g rye + 50 g water, evening: big bubbles, the starter is active, CO2 production evidenced by tickling in nose, fed with 60 g rye + 60 g water and 2 x 100 g samples taken for fridge and freezer as fallback points
• August 6: morning: 50 g rye + 50 g water, first successfull bread made with the starter

I show my raw data to illustrate that it’s not straightforward, even with temperature control.

A fool proof starter – is it possible?
What I’m hoping to achieve can be summarized as follows: A “fool proof”, robust and quick method to obtain a sourdough starter that’s as simple as possible, using only flour and water (possibly with addition of some fruit) without having to waste anything of the starter. Temperature is maintained using a thermostated water bath. Preferably it should be possible to adjust the fermentation quotient (ratio of lactic acid/acetic acid) and the total titrable acid content by means of temperature, time and hydration/dough yield.

The International Journal of Gastronomy and Food Science (IJGFS) is planned for launch this year. Elsevir is mentioned as a publisher, but there is currently no further information on the Elsevir website. The journal is initiated by AZTI-tecnalia, a Spanish technology center specializing in marine and food research, in collaboration with ALICIA, a Catalan research centre focusing on technological innovation in kitchen science and the dissemination of agronourishment and gastronomic heritage. The restaurant Mugaritz and the websites aliment@tec and Ciencia y gastronomia also have their logos on the IJGFS website. The objective of the journal is to “fill the gap in the expanding fields of Gastronomy and Food Science, by adopting a scientific approach”.

In addition to scientific papers and review articles they plan to publish “original recipes” which is novel and unusual for a scientific journal. I must say that I’m curious about how the peer review process of “original recipe” contributions will be. How do you judge novelty and originality of a recipe? For scientific work this is easier as there are comprehensive databases of previously published work. No such database exists for recipes. Nevertheless, it is a goal for the journal to become a communication channel betwen chefs and food scientists, and we’ll probably see recipe contributions from both groups. If the concept of the journal works out and they actually manage to get contributions from chefs and scientists (and hopefully also some joint contributions) the journal will become a quite unique addition to the more food science oriented journals!

From the descriptions it seems that the journal will cover scientific, technological and practical aspects of molecular gastronomy, even though they completely avoid using the molecular gastronomy! Instead they list the following areas of interest: Gastronomy in perspective, Food Science and Gastronomy and Innovation in Gastronomy. Regardless of which labels they use, this all sounds very interesting to me!

An invitation to contribute has been sent out by email and in case you didn’t receive one but would like to contribute I’d recommend you to check out the online invitation and fill out the application form. I’ll return with an update once the journal goes live.

Molecular gastronomy: a food fad or science supporting innovative cuisine? Cesar Vega, Job Ubbink (Trends Food Sci Technol 2008, 19(7), 372-382)

The concepts, history and approaches of molecular gastronomy are discussed with an emphasis on the relation to food science and technology. A distinction is made between molecular gastronomy and science-based cooking (…) We discuss how chefs are dealing with the available systematic knowledge on food and cooking, and how molecular gastronomy can facilitate the cumbersome, but much needed discussions among food scientists and chefs.

Molecular Gastronomy: A Food Fad or an Interface for Science-based Cooking? Erik van der Linden, David Julian McClements and Job Ubbink (Food Biophysics, 2008, 3(2), 246-254)

A review is given over the field of molecular gastronomy and its relation to science and cooking. We begin with a brief history of the field of molecular gastronomy, the definition of the term itself, and the current controversy surrounding this term. (…) On the one hand, it can facilitate the implementation of new ideas and recipes in restaurants. On the other hand, it challenges scientists to apply their fundamental scientific understanding to the complexities of cooking, and it challenges them to expand the scientific understanding of many chemical and physical mechanisms beyond the common mass-produced food products.

The life of an anise-flavored alcoholic beverage: Does its stability cloud or confirm theory? Elke Scholten, Erik van der Linden, Hervé This (Langmuir 2008, 24(5), 1701-1706).

The well-known alcoholic beverage Pastis becomes turbid when mixed with water due to the poor solubility of trans-anethol, the anise-flavored component of Pastis in the water solution formed. This destabilization appears as the formation of micrometer-sized droplets that only very slowly grow in size, thus expanding the life of the anise-flavored beverage. (…) experiments on Ostwald ripening show an increase in stability with increasing ethanol concentration, the results based on our interfacial tension measurements in combination with the same Ostwald ripening model show a decrease in stability with an increase in ethanol concentration.

Formal descriptions for formulation, Hervé This (Int J Pharm 2007, 344(1-2), 4-8)

Two formalisms used to describe the physical microstructure and the organization of formulated products are given. The first, called “complex disperse systems formalism” (CDS formalism) is useful for the description of the physical nature of disperse matter. The second, called “non periodical organizational space formalism” (NPOS formalism) has the same operators as the CDS formalism, but different elements; it is useful to describe the arrangement of any objects in space. Both formalisms can be viewed as the same, applied to different orders of magnitude for spatial size.

Lavoisier and meat stock Hervé This, Robert Meric, Anne Cazor (Compt Rend Chim 2006, 9(11-12), 1510-1515).

Antoine-Laurent de Lavoisier published his results on meat stock’ preparations in 1783. Measuring density, he stated that food principles’ were better extracted using a large quantity of water. This result was checked.

A recent article (found via Harold McGee’s News for curious cooks) featuring Heston Blumenthal as a co-author emphasizes the huge difference in glutamic acid contents between the flesh and pulp of tomatoes. Glutamic acid and it’s sodium salt (mono sodium glutamate or MSG) are responsible for the characteristic umami taste. On average the flesh contains 1.26 g/kg glutamic acid whereas the pulp on average contains 4.56 g/kg glutamic acid. Similar differences are found for several nucleotides which posess similar taste qualities. These differences can explain the perceived difference in umami taste between the flesh and pulp of tomatoes – and is worthwhile considering when cooking.

Those concerned about food with added MSG should read the chapter about MSG in John Emsley’s excellent book “Was it something you ate?”. First thing to note is that you can’t be allergic to MSG because our body needs glutamic acid to function properly. Emsley retraces the history of the Chinese restaurant syndrome (CRS) back to it’s roots in 1968 when a letter was published (R.H.M. Kwok, New Engl. J. Med. 1968, 278, 796) describing a series of symptoms experienced after having eaten at a Chinese restaurant. To make a long story short, in 1993 Tarasoff and Kelly reviewed previous studies and conducted a double blind test which led to the following conclusion:

… ‘Chinese Restaurant Syndrome’ is an anecdote applied to a variety of postprandial illnesses; rigorous and realistic scientific evidence linking the syndrome to MSG could not be found.

Following the publication, a critical reply was published by Adrianne Samuels, to which the authors have replied.

Anyway, it was in John Emsley’s book that I first read about the record levels of glutamic acid found in parmesan cheese: 12 g/kg! That’s nearly three times the amount found in tomato pulp. In some cheeses there is so much that it crystallises out in small white crystals visible to the naked eye. Think about this when you sprinkle your food with parmesan. And if you ever wondered why Italian food tastes so nice, now you know that MSG is one reason (but of course not the only one …).