The chemistry and use of lysozyme as a food preservative and a pharmaceutical are reviewed. Lysozyme inhibits the growth of deleterious organisms, thus prolonging shelf life. Chemicals used to improve the preservative effect of lysozyme and those that inhibit the enzyme are discussed, along with the stability of lysozyme in various chemical environments. Lysozyme has been used to preserve fresh fruits and vegetables, tofu bean curd, seafoods, meats and sausages, potato salad, cooked burdock with soy sauce, and varieties of semihard cheeses such as Edam, Gouda, and some Italian cheeses. Lysozyme added to infant‐feeding formulas makes them more closely resemble human milk. Lysozyme has been used clinically in the treatment of periodontitis, administered in chewing gum, and implemented to prevent tooth decay. It has also been administered to patients suffering from cancer for its analgesic effect and has been used as a potentiating agent in antibiotic therapy.

The chemistry of lysozyme and its use as a food preservative and a pharmaceutical.

Publisher Summary This chapter discusses “warmed–over” flavor (WOF) in meat, poultry, and fish. In the first section, the classification and significance of lipids is described. It explains the structure of lipids and the composition of animal fats. The role of lipids in meat flavor, both the desirable and undesirable, are presented. Next section discusses the mechanisms of lipid oxidation. It delves into the topics of autoxidation, catalysts of lipid oxidation, comparison of heme and nonheme iron as pro–oxdidants in muscle tissue, and phospholipid oxidations. In the subsequent section, development of WOF, the species differences in WOF, influence of deboned meat, influence of heating, influence of chopping and emulsifying and effects of curing are explained. A discussion on the prevention of WOF in meat, poultry, and fish is also presented in the last section.

“Warmed-Over” Flavor in Meat, Poultry, and Fish

Effect of rosemary extract, chitosan and α-tocopherol on lipid oxidation and colour stability during frozen storage of beef burgers


Postmortem changes of sardine muscle during 15 d storage at 0 °C were studied to evaluate its quality and functionality. No microbial deterioration was detected since trimethylamine and histamine concentration remained low with final values of ≤ 1.62 mg/100g and 0.00018 ppm, respectively. A final proteolytic activity ≤ 20 μg Tyrosine/min/g protein was detected. Lipid oxidation from moderate to advanced was detected after day 5 with values of 31.8 to 33.9 meq/kg and 26 mg/kg for peroxide value and thiobarbituric acid value respectively. Muscle protein showed no gel-forming ability. Extraction of myofibrillar protein decreased 45% and 81% at day 5 and 15 respectively. Overall results indicated that good quality was maintained during the storage period with a final K value of 50.7% when proper handling practices were implemented.

Postmortem Biochemical and Functional Characteristic of Monterey Sardine Muscle Stored at 0 °C

Structural characterisation, physicochemical properties and antioxidant activity of polysaccharide from Lilium lancifolium Thunb.

SUMMARY— During an 8-week storage period of bovine muscle at −4°C, the total extractable protein content dropped from 91 to 51%. This decline, accompanied by a decrease in water-binding capacity of muscle, was primarily caused by the insolubilization of both sarcoplasmic proteins and actomyosin. The increase in the free fatty acid content from about 1.6 to 9.1% over the 8-week period may be attributed to phospholipid hydrolysis. The TBA number rose progressively throughout the entire storage period while the peroxide value increased to a maximum in 2 weeks of storage and then decreased to a constant value of 7.

Chemical deterioration of frozen bovine muscle at -4°C.

SUMMARY— Organoleptic and chemical deterioration of freshwater whitefish muscle frozen at −10°C for periods up to 16 weeks was assessed. As frozen storage of muscle progressed, the toughness and rancidity of baked muscle increased. The solubility of the myofibrillar protein fraction, “actomyosin,” dropped from about 72 to 22% over the 16 week storage period of whitefish muscle. No change in the solubility of sarcoplasmic protein in frozen stored muscle was observed. However, with polyacrylamide disc electrophoresis, two new sarcoplasmic protein bands were detected after 16 weeks of storage. With storage of frozen muscle, water-binding capacity diminished. Although the total lipid and cholesterol contents of muscle remained constant throughout frozen storage, the phospholipid content decreased as the free fatty acid content increased. Oxidative deterioration of lipid in frozen muscle was estimated.

A. Awad

Papers

Chemical deterioration of frozen bovine muscle at -4°C.

Deterioration of Fresh-Water Whitefish Muscle During Frozen Storage at −10°C