Postmortem protein phosphorylation in garlic-treated meat during refrigerated storage: Glycolytic and proteolytic...

The effects of sarcoplasmic and myofibrillar protein phosphorylation on meat quality were studied, focusing on the influence of garlic. Postmortem protein phosphorylation, glycolytic and proteolytic changes were investigated in ground meat with 0 % (control), 1 %, and 2 % garlic during 4 days of refrigerated storage. Twenty sarcoplasmic (S) protein bands were detected using SDS-PAGE. With an increased garlic ratio significantly reducing total phosphorylation (P < 0.05), especially at 48 h postmortem, and the phosphorylation increased in bands S6, S13 and S17, decreased in bands S1, S16, S18, S19 (P < 0.05). The interaction between garlic ratio and postmortem time significantly (P < 0.05) affected the phosphorylation of S2 and S3 bands. Possibly related to the level of sarcoplasmic protein phosphorylation, increasing garlic ratio slowed glycolysis, resulting in lower lactic acid (P < 0.001) and higher pH values (P < 0.01). Additionally, the contents of glycolytic intermediates, including glucose, acetic, pyruvic, citric and succinic acids, were significantly (P < 0.05) higher in control meat compared to garlic-treated ones. For myofibrillar proteins, 14 bands were detected, and phosphorylation of bands M10 and M11 decreased (P < 0.05) with increasing garlic ratio. The phosphorylation of M5 band was significantly (P < 0.05) affected by the interaction between garlic ratio and storage time. Garlic-treated meats were more tender (P < 0.01), possibly due to myofibrillar proteins with decreased phosphorylation, and had higher levels of Lys, Ser + Asn, Tyr amino acids (P < 0.01). The study revealed that protein phosphorylation, influenced by garlic incorporation, might play a critical role in regulation meat quality, likely through its effects on glycolysis and proteolysis.