Preventing lipid oxidation of precooked meat

The advantages of precooked meats are clear, just as it's clear that "warmed over flavor" (WOF) isn't one of them. The product may look like meat, but it may taste like cardboard once it is reheated.

WOF is the result of lipid oxidation, which can occur when cooked meat is refrigerated. In a nutshell, the oxidation of lipids — or unsaturated fatty acids — creates a stale taste owing to the release of ionic iron during cooking. The onset of WOF is rapid during storage, with oxidized flavors typically detectable within 48 hours.

One obvious solution is to flash-freeze the product, though this approach may present taste and texture issues all its own.

For red meat processors, the good news is that beef and pork tend to be less susceptible to WOF than turkey and chicken. Further, WOF isn't associated with cured product thanks to the presence of nitrites, which function as antioxidants. The bad news: Science is still struggling to lick WOF, primarily by preventing or slowing oxidation.

Current practices emphasize introducing antioxidants to product, though other methods — including reducing heat during cooking as well as maintaining proper product temperatures before and after — also may slow or prevent oxidation.

Meanwhile, many common antioxidants may do the trick.


Solution No. 1: Butylated hydroxyanisole and butylated hydroxytoluene
Both of these phenolic compounds get the job done, particularly when used in combination. Oxygen reacts preferentially with the two rather than oxidizing fats and oils, thereby preventing spoilage.

Because both are strong synthetic agents, USDA is very specific about their use, having approved them at 0.01 percent of fat content for select applications, including fresh pork, brown-and-serve sausage, fresh Italian sausage, pre-grilled beef patties and fresh sausage made from beef or beef and pork.


Solution No. 2: Natural ingredients
Rosemary extract, one of the better-known natural antioxidants, is among the most effective in retarding lipid oxidation. In comparison to most synthetic solutions, it also is more thermally stable. Some applications blend rosemary extract and citric acid to achieve the same end.

Solution No. 3: Mixed tocopherols
A synthetic form of vitamin E, mixed tocopherols compare favorably to other antioxidants, though various types aren't created equal. So-called high-alpha types promote higher vitamin E activity and, as a result, perform well as nutrients. They also are good antioxidants, but not as good as low-alpha tocopherols, since the latter contain greater amounts of gamma and delta tocopherols, which promote higher levels of antioxidant activity.

As with BHA and BHT, USDA rules apply. Usage may not exceed 0.03 percent of fat content. And mixed tocopherols can't be used in combination with other antioxidants.


Solution No. 4: Citric acid
Best as an antioxidant in a secondary role, this ingredient is a weak organic acid found in citrus foods. It typically works synergistically with primary antioxidants to slow or prevent lipid oxidation.