This week's luck winner... soy sauce!!
Food Reward Friday isn't just about culinary monstrosities created by profit-hungry corporations. It's also about the everyday items, lurking in all of our pantries, which increase the reward value of our diet and sometimes cause us to overeat.
Soy sauce is a traditional flavor enhancer used in many parts of Asia, and it has been around for at least 1,500 years. It's a concentrated mixture of amino acids and salt, produced by the fermentation of soybeans and grains. The fermentation process breaks down the protein in soybeans, releasing amino acids including glutamate-- the "umami" amino acid that gives soy sauce its meaty punch.
The combination of meaty glutamate and salt is a potent one for our reward-sensitive brain regions, which are attuned to both flavors. Chefs have long known that glutamate, found in soy sauce but also industrially produced in crystalline form, draws people to their food.
The history of food processing technology has been one of gradually increasing the concentration of the rewarding "active ingredients" in food, and soy sauce falls squarely in this pattern. The original way of getting glutamate was via cooked meat, and this may be why our brains are attuned to it. Eventually, we figured out how to get more glutamate by boiling bones or seaweed in water. Then, we invented high-glutamate fermented sauces like fish sauce and soy sauce. The final step was learning to produce crystalline monosodium glutamate, the purest form of the rewarding "active ingredient" the human brain seeks. MSG is the crack cocaine of glutamate.
With each technological advance, the link between reward value and nutritional value became weaker. MSG is the culmination of this trend-- it's pure flavor but it contains virtually no nutritional value. Soy sauce lies somewhere between meat and MSG.