### Flavor Networks

December 2, 2011

My longtime employer nicely provided a fitness center for its employees. Mid-day, I would exercise on a treadmill while watching television. Since daytime television is uniformly awful, I eventually settled on watching the Food Network. My exercise time coincided with a show about desserts hosted by Debbi Fields of the famous Mrs. Fields cookies.

In watching that show, I saw that most of the dessert recipes contained a set of common ingredients, such as flour, sugar, butter, oil, milk and eggs. To make a new recipe, you just needed to vary the proportions of these and add a pinch of some other ingredients, such as cinnamon, vanilla, or chocolate.

If I had been adventuresome, I would have written a computer program to randomly generate dessert recipes, baked them up, and seen how they tasted. It would have been a Monte Carlo calculation, with ingredient distributions derived from existing recipes. Alas, all this eating would have been contrary to the idea of my being at the fitness center in the first place.

No scientific idea is lost forever. It's generally rediscovered by another scientist. An eclectic group of scientists from the Department of Physics, Northeastern University (Boston, MA), the Dana-Farber Cancer Institute, Harvard University (Boston, MA), the School of Informatics and Computing, Indiana University (Bloomington, IN), and the Cavendish Laboratory, Cambridge University (Cambridge, UK) has recently published a paper on the arXiv Preprint Server that analyzes the connections between food ingredients in western and non-western foods.

The number of potential food recipes is huge. If a typical recipe has just eight ingredients, there would be about 1015 possible combinations using the 300 most common ingredients. The authors point out that this could still be an underestimate, since one authoritative source lists 1,000 ingredients,[2] and there could be ten ingredients per recipe, for a total of 1023 combinations. Obviously, humans are exploiting just a small fraction of the "culinary space," although most of these combinations would be quite unpalatable.

The authors find that western cuisines use ingredient pairs that share many flavor compounds. This finding supports what's called the "food pairing" hypothesis that some foods seem to naturally go together. A strange example of this is the discovery that chocolate and cauliflower taste good together.[3] East Asian cuisines, however, avoid such flavor pairing.

So, what ingredients are used most often? The following table shows the most popular food ingredients for North American and East Asian cuisine.

Contributing ingredients to North American and East Asian cuisine. The numbers are the relative contributions of each ingredient to the total cuisine, as defined in Ref. 1. These are ranked in order of greatest use from top to bottom.[1]
 North American Χi East Asian Χi milk 0.529 rice 0.294 butter 0.511 red bean 0.152 cocoa 0.377 milk 0.055 vanilla 0.239 green tea 0.041 cream 0.154 butter 0.041 cream cheese 0.154 peanut 0.038 egg 0.151 mung bean 0.036 peanut butter 0.136 egg 0.033 strawberry 0.106 brown rice 0.031 cheddar cheese 0.098 nut 0.024 orange 0.095 mushroom 0.022 lemon 0.095 orange 0.016 coffee 0.085 soybean 0.015 cranberry 0.07 cinnamon 0.014 lime 0.065 enokiatke 0.013 tomato -0.168 beef -0.2498 white wine -0.0556 ginger -0.1032 beef -0.0544 pork -0.0987 onion -0.0524 cayenne -0.0686 chicken -0.0498 chicken -0.0662 tamarind -0.0427 onion -0.0541 vinegar -0.0396 fish -0.0458 pepper -0.0356 bell pepper -0.0414 pork -0.0332 sesame seed -0.041 celery -0.0329 black pepper -0.0409 bell pepper -0.0306 shrimp -0.0408 red wine -0.0271 shiitake -0.0329 black pepper -0.0248 garlic -0.0302 parsley -0.0217 carrot -0.0261 Parmesan cheese -0.0197 tomato -0.0246

Network-oriented papers always have some very pretty figures, such as the one shown below. See the caption of the original figure for an explanation.[1]

This figure shows the connections between food ingredients. No, you're not expected to read the tiny characters. Click on the image for a more readable version, and see the caption of the original figure for an explanation. (via arXiv Preprint Server, Fig. S4 of Ref. 1).

### References:

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