Rancid meat results largely from lipd oxidation (fat spoilage), a process that occurs most rapidly once meat has been cooked, according to Texas A&M meat scientist Ki Soon Rhee in College Station. Since this process is induced by oxygen and not by microbes, freezing won’t prevent it, which explains why fighting rancidity has become one of the leading problems facing purveyors of frozen, precooked meats. But research by Rhee indicates there’s natural antioxidant food ingredient that will retard development of those objectionable “off” flavors associated with rancidity–even in leftovers or long-warmed cafeteria offerings.
It’s cottonseed flour. Seeds of normal cotton plants have pigment glands containing gossypol, a chemical toxic to humans. The high-protein flour Rhee uses comes instead from a glandless variety, and has been defatted to reduce both its high of content and its susceptibility to rancidity. Initially Rhee mixed the flour with fresh uncooked ground beef. Though it slowed development of rancidity after cooking, Rhee suspected many consumers would object to having any additive in their otherwise pure beef. So now she’s concentrating on slipping some cottonseed flour into the coatings on breaded and batter-dipped meat products. In recent experiments, Rhee coated half her ground beef patties with batter made solely of wheat flour, and the rest in batter made from a 50/50 mix wheat and cottonseed flours.
After refrigerating these cooked “chicken-fried steaks” for five days, she found that those in wheater batter registered a thiobarbituric acid (TBA) test value of 10.5 to 10.9–unquestionably and very objectionably rancid. (TBA tests are the leading chemical tests for rancidity.) By contrast, 50/50 batter-dipped patties developed a TBA value of just 2.7 in the first test and 4.
3 in a second. Rhee attributes the second, higher rancidity score to using meat that had been frozen before cooking, rather than using fresh meat. Postcooking refrigeration was used to accelerate the rate of deterioration that would occur in the freezer. “Refrigerated [cooked] meat won’t last even a day before it becomes unacceptable to sensitive people,” says Rhee, noting that she is among the more sensitive, finding unpalatable the rancidity corresponding to a TBA value of just 1.2. Even cafeterias can benefit from Rhee’s studies.
Though rancidity can occur at room temperature in just two hours, hamburgers or roast beef slices can be held warm for hours or be stored as leftovers–without a tast change–if immersed in a gravy or au jus solution containing cottonseed flour.