EFFECT OF SOME NATURAL ANTIMICROBIALS AND ANTIOXIDANTS ON QUALITY AND SHELF-LIFE OF LAMB MEAT

Abstract

Meat is defined as those animal tissues which are suitable for use as food. Meat has traditionally held a special place in the human diet because of its appealing flavour and texture and its high nutritional value (Steel, 2004).

Lamb meat is an important source of proteins and fats. Lamb meat, especially, has the highest level of polyunsaturated fatty acid (PUFA) of linolenic acid 18:3 (ro -3) (1.37 mg/100 mg) as compared to beef or pork meats (0.70 and 0.95 mg/100 mg, respectively), which has beneficial effects to the health. It helps to control blood cholesterol levels. However, PUFA acts as a substrate which favours the beginning ofthe oxidative process in meat. Lamb meat, also, is an important source of trace elements such as iron, zinc and copper, and range ofB vitamins and vitamins A and D (Lombardi-Boccia et al., 2005).

In the countries of North Africa and the Middle East bordering the Mediterranean, sheep is generally the most preferred meat, because sheep meat can be considered as more desirable, juicier, tender, flavourful and fatter than goat meat (Safiudo eta!., 1998).

The numbers of sheep in Libya for the year 2007 was 6.50 million heads and meat production for the same year was 189.00 metric tons while meat from sheep and goats represented about 147,000 metric tons (Arabic Agric. Statistics Year Book, 2008).

Lamb meat being a highly perishable commodity requires special attention during handling/storage/transportation. Lipid oxidation involves degradation of polyunsaturated fatty acids and generation of free radicals, leading to the deterioration of proteins, the oxidation of -heam pigments, and the generation of rancid odours. The addition of antioxidants is required to preserve flavour and coloure and to avoid vitamin destruction. Also microbial contamination has always been a great concern to the meat industry. The growth of microorganisms in meat is responsible for meat quality reduction and loss of revenues and can lead to serious health problems. The control of microbial contamination has been a major endeavor of the meat industry. Meat preservation is one of the most important areas that are continuously investigated in order to improve meat quality and safety (Aymerich et al., 2008). The most common method of prolonging the shelf life of meat is the use of refrigeration. The term refrigeration is the confined to the use of temperatures between (-2 and5°C} for the storage of meat. Almost all fresh meat is stored under such refrigeration. Meat is also preserved by the processes of freezing, thermal processing, some chemicals, irradiation, and dehydration (Nawar, 1996). Leistner, (2002) describes the principles of hurdle technology and states that if the initial microbial load is substantially reduced as a result of carcass decontamination procedures; fewer microorganisms are present, which are then more easily inhibited in subsequent processing steps. A combination of hurdles can ensure stability and microbial safety of preserved food. The most important hurdles used in food preservation are temperature (high or low}, water activity (aw), acidity (pH), redox potential (Eh), preservatives (e.g., nitrite, sorbate, sulfite), and competitive micro-organisms (e.g., lactic acid bacteria (Zhou et a!., 20 I 0). In the food industry, synthetic antioxidants are mostly used as they are pure, cheap and readily available. Food antimicrobials are chemical compounds added to or present in