Effects of Frozen Storage on Chicken Muscle Proteins a

SUMMARY Quantitative examination of chicken muscle proteins showed that protein extractability in both breast and leg muscle decreased during frozen storage because of loss of solubility of actomyosin fraction. This decrease accompanied a decrease in the sulfhydryl‐group content of muscles and loss in myosin‐adenosinetriphosphatase activity. The stroma‐protein fraction remained unaffected, and the sarcoplasmic‐protein fraction decreased only after long storage. In the non‐protein‐nitrogen fraction, the amount of free amino acids and other protein‐breakdown products increased as a result of proteolysis. The rate of these changes depended directly on storage temperature and time. It is suggested that chicken muscles in frozen storage undergo proteolysis and that the myofibrillar‐protein fraction is denatured.