Effects of polyphosphates on frozen chickens.

The main objective of this work was to study the antioxidant properties of polyphosphates in frozen chickens, which were obtained during supervised factory trials, and to propose reasons for this effect. Previous work has been mainly concerned with why polyphosphates increase the water holding capacity (WHC) of meat.After a brief review of the types, uses, and effects of polyphosphates in the food industry, their specific use and effects in frozen chicken are discussed. The factors which affect WHC and the lipid and fatty acid compositions of chicken tissues are discussed; as is the mechanism of the autooxidation reaction, and the theories about the mode of action of polyphosphates. Lipid and fatty acid compositions were determined by chromatographic methods. The degree of autooxidation was determined by the thiobarbituric acid(TBA) test. The distribution of added polyphosphates and the ionic composition of individual muscles were determined by Inductively Coupled Plasma Atomic Emission Spectrometry (IOPAES). The hydrolysis of polyphosphates was studied using thin layer chromatography(TLC) and phosphorus-31 Fourier transform nuclear magnetic resonance ([31] P-FTNMR) . The reasons for choosing thesetechniques, and the results of preliminary tests are given.Polyphosphate treatment was found to result in cooked muscles having reduced TBA numbers and lower levels of calcium and magnesium than untreated muscles; but to have little effect on chill-water uptake, thaw and cooking losses, and lipid and fatty acid composition. Added polyphosphates were found in the pectoralis major and pectoralis minor muscles, but leg muscles contained either none or very small amounts. Polyphosphates were found to undergo considerable hydrolysis immediately on mixing with excised muscle, and during prolonged frozen storage of the whole chicken. The general conclusions concern the lipid and fatty acid composition of chicken muscles, the autooxidation process, and the scope and reliability of the TBA test. It was concluded that polyphosphates remove calcium and magnesium from thawed muscle, and that they perhaps associate with phospholipids.