Studies of lipid peroxidation mechanisms that lead to the development of warmed-over flavour in red meat products

Summary

Current trends show that meat consumers are showing an increased demand for pre-cooked 'heat and eat' convenience meals. The worldwide market potential for meat-based ready meals was estimated to be approximately $20 billion in 2000 with an annual growth of 4%. Home meal replacement - HMR - is one of the fastest growing segments of the food industry. Meat usually represents the main component of a meal and the form in which it is presented has an important impact on consumer acceptance. For example, over 30% of beef produced goes into cured meat products and while these products are oxidatively stable, they do not taste like freshly cooked beef and are not acceptable to consumers as a HMR. Consumers display a clear preference for the flavour and aroma of freshly cooked beef and expect these to be present in a beef-based HMR. Once cooked, beef is usually served immediately and not kept stored for later consumption. This is due to the rapid development of the specific and undesirable flavour associated with reheating refrigerated cooked beef.

In 1958, the American meat researchers Margaret Tims and Betty Watts introduced the term "warmed-over" to describe this off flavour and in the 45 years that have followed much research effort has been devoted to its solution. Warmed-over flavour - WOF - results from the rapid oxidation of lipids in cooked meat. Chilled raw meat is oxidatively stable for several weeks whereas in the cooked product rancidity can be detected within hours. WOF is characterised by loss of fresh meat aroma and the development of flavours and aromas described by consumers as "stale", "rancid", "painty" or "cardboard-like". WOF is a major problem in the restaurant, fast-food, institutional-service and airline food catering industries. Therefore, the production of novel heat and serve pre-cooked beef meals for these markets and the HRM market must address the issue of WOF development during storage and subsequent serving of the product. The early development of WOF in ready-to-eat meat meals could be masked through the inclusion of condiments and sauces. However, free radicals, lipid hydroperoxides and malondialdehyde produced during the oxidation process have been implicated in the pathophysiology of diseases such as atherosclerosis and cancer. The prevention of WOF in pre-cooked meat products has potentially important health implications as well as its impact on consumer acceptability.