KFC’s secret recipe may or may not have been revealed recently, but the science behind why it tastes so good is clear.
Steve Witherly, PhD, devoted a whole section to KFC in his 2007 book, “Why Humans Like Junk Food.” Keep reading to see insights pulled from the book and our interview with Witherly.
Because humans evolved as foragers, our brains learned to recognise and desire things that pack a lot of calories.
Caloric density scale ranges from 0 for water to 9 for pure fat. While raw chicken breast without the skin has a caloric density of 1.35, KFC's original chicken breast scores 2.3: the extra crispy version gets a 2.9. The skin by itself scores an intoxicating 5.0.
'Ergo, the chicken is only a vehicle for eating the skin,' writes Witherly.
Humans have evolved to love salty things -- a result of our bodies needing sodium to function properly while our sweat glands constantly deplete the supply, according to Witherly.
One KFC original chicken breast contains 1.1 grams of sodium, amounting to a staggering 48% of your recommended daily value.
All told, salt makes up around 1.85% of the weight of the meal. That's right around the ideal level of salt for human enjoyment of dry foods, according to Witherly. His theory is that it's perfect for us, since a bite of it combined with the saliva in your mouth brings the salt content to approximately the 1% level found in your blood.
KFC adds the infamous flavour-booster monosodium glutamate to dozens of items, as detailed on the company website. It also uses foods naturally high in effectively similar free glutamates like chicken.
MSG enhances salt taste and salt taste pleasure, while also triggering the brothy umami taste.
Although MSG has gotten a bad rap, most scientists agree that it's safe, as there have been no studies showing that it causes headaches or other supposed negative effects. Witherly himself likes to use it (combined with salt at a 9:1 ratio) in his home cooking.
Colonel Sanders' secret here is the use of a pressure fryer, something that can be
dangerous without just the right equipment and methods. The pressure fryer not only lets KFC cook chicken faster and with less oil but also locks in moisture.
Witherly theorizes that it may also drive some of that salt and MSG into the meat, making it that much more delicious.
Semi-emulsified means it's a partial mixture of water and fat. Humans like emulsifications because all the salt or sugar gets concentrated in the water part, making for an extra flavorful rush when it hits your mouth.
While traditional fried chicken takes a few seconds to activate your taste buds, KFC's moist skin gives an immediate surge of salt and MSG.
Food scientists have observed that people like the excitement of biting through different textures, whether fried tortilla and ground beef, cookie wafers and creme, or crispy breading and moist chicken. People also enjoy the combination of opposite traits, such as salty snacks and beer.
Biting into KFC yields both the textural and tastable excitement you're looking for.
White pepper, used by KFC in astonishing amounts, and black pepper contain a powerful compound called piperine.
Piperine activates receptors for tingling and burning in the mouth. It also activates special receptors in the brain, giving it potential antidepressant-like qualities (though probably not in very small doses).
Piperine may also aid digestion. This, too, can make you crave it. 'One of the theories I've put forth is that if you eat something that does something to you and it's beneficial, your brain figures it out ... it wants you to do it again,' Witherly says.
Food scientists talk about non-specific aroma quality as a powerful factor in popular foods from Doritos to Coke. When our brain can't easily identify a food's dominant flavour, we're less likely to get bored of it.
KFC, with its secret 11 herbs and spices, as well as unusual flavour compounds derived from pressure cooking, fits the bill.
'If say KFC was rosemary-dominant aroma profile, the brain can burn out on rosemary really fast, but not if the eleven herbs and spices don't have a distinctive aroma that the nose and brain can memorise,' Witherly said in email. 'You just can keep eating this forever without sensory burnout.'
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