A compound natural preservative (CNP) was produced by mixing clove cinnamon extracts with tea polyphenol, chitosan, propolis, nisin and lysozyme. Its effects on microbiological [total aerobic counts (TACs)], chemical [total volatile base nitrogen (TVB-N), 2-thiobarbituric reactive substances (TBARS), total reducing activity (TRA) and pH values], and colorimetric characteristics of chilled beef and mutton that were kept under vacuum packaging during refrigerated storage at 4 ± 1℃ were investigated for 4 weeks. Results indicated that the CNP significantly inhibited the growth of microbes, improved TRA values, and decreased TBARS and TVB-N values to some extent especially at the later storage time, but had no obvious advantage in maintaining the color stability of beef and mutton when compared to lactic acid (LA, positive control) and sterile distilled water (DW, negative control). The shelf-lives of chilled beef and mutton were observed to be 3 − 4 weeks for the CNP treatment. The susceptibility of meat species to lipid oxidation was greater in beef than mutton, but spoilage as a consequence of bacteria load was greater in mutton than beef.Keywords: compound natural preservative, beef, mutton, vacuum packaging, refrigerated storage *To whom correspondence should be addressed. haojm.1@163.com (J. Hao)
IntroductionMany food products are perishable by nature and require protection from spoilage during their preparation, storage and distribution for the desired shelf-life. The spoilage of food is a complicated process involving the interactions of microbial, physical, and chemical changes. Microbial contamination and lipids oxidation in foods during processing and storage are the major causes of food-borne illnesses and loss of shelf-life (Rao et al., 2008). A cold distribution chain is imperative, but it cannot assure the quality and safety of all perishable foods by itself. Therefore, additional preservation techniques such as physical processes (e.g., irradiation and packaging methods), artificial chemical methods (added calcium lactate, sodium succinate, and so on), and natural biological antimicrobial and/or antioxidant ingredients (adding plant essential oils or extracts, etc.) are being used or investigated for their application to food products (Nam et al., 2001;Zhu et al., 2009;Kong et al., 2010).Meat is recognized as one of the most perishable foods, and consumers prefer meats that are high in polyunsaturated fatty acids (PUFAs) and myoglobin, for its high ferrous iron and phospholipid content (Enser et al., 1996;Rhee et al., 1996). Some researchers have reported that crude clove extracts have the greatest total phenolic contents and ferricreducing antioxidant power out of 32 tested spices, are also strongly inhibitory of TBARS formation (Wojdyło et al., 2007), and thereby improved the quality and nutritional value of cooked pork patties (Kong et al., 2010). Cinnamon was the second most powerful extract (Kong et al., 2010). Moreover, preservative effects increased with spice concentrations. The incorporatio...