Effects of Photooxidation and Oxygen on Beef Quality and Physicochemical Properties of Protein during Storage

In order to explore the effects of light and oxygen on the storage quality of beef and the physicochemical properties of myofibrillar protein, the pH, color, total volatile basic nitrogen (TVB-N) content, malondialdehyde (MDA) content, microstructure, peptide composition, carbonyl, sulfhydryl and dimeric tyrosine contents of protein in fresh beef were determined during 0–5 days of storage at 4 ℃. The results showed that under natural storage conditions (aerobic, natural light and 4 ℃), the TVB-N and MDA contents increased with storage time, exceeding the standard limit on day 5; the microstructure of beef changed with the occurrence of crosslinking and degradation fragments, and its quality deteriorated and was no longer fit for consumption. Anaerobic and dark conditions could delay beef quality deterioration. As storage time increased, the carbonyl content of myofibrillar protein gradually increased, and the sulfhydryl content gradually decreased. Oxygen could more accelerate the increase of carbonyl groups than light, while light was more effective in reducing sulfhydryl groups. In summary, fresh beef should not be stored for four days under light and aerobic conditions. Light and oxygen can promote protein oxidation and cross-linking aggregation.