Effect of Grape Seed Extract on Eating Quality of Repeatedly Frozen-Thawed Altay Sheep Meat

This study aimed to examine the effects of grape seed extract (GSE) on enhancing the quality of Altay sheep meat during repeated freeze-thaw cycles. The surface of the Longissimus dorsi muscle was sprayed with 0.5 g/100 mL GSE aqueous solution prior to undergoing 1, 3, 5 or 7 freeze-thaw cycles. At each cycle, meat color, myoglobin oxidation status, pH, shear force, thiobarbituric acid reactive substances (TBARS) value, total volatile basic nitrogen (TVB-N) content and volatile compound profile were determined. The results indicated that with increasing freeze-thaw cycles, lightness (L*), redness (a*), relative content of oxymyoglobin (OMb), pH, and shear force decreased; yellowness (b*), TBARS value, and relative contents of deoxymyoglobin (DMb) and metamyoglobin (MMb) showed an increasing trend; TVB-N contents initially increased and then decreased. The incorporation of GSE was found to mitigate the pH decrease and significantly lower the TBARS value (P < 0.05) during freeze-thaw cycles, but had no significant effect on the color, shear force or TVB-N content of mutton. Additionally, the levels of major volatile flavor compounds such as hexanal, 1-octene-3-ol, (E,E)-2,4-decenal, (E,Z)-2,4-decenal, (E)-2-octanal, octanal, heptanal, 3-octanone, carbon disulfide, and 2-pentylfuran initially rose and then fell with increasing freeze-thaw cycles, resulting in flavor deterioration. Compared with the blank group, GSE addition significantly curtailed the formation of aldehydes, ketones, alcohols, and furans resulting from lipid oxidation during repeated freeze-thaw cycles, thereby improving mutton flavor. This research provides a theoretical foundation and technical support for the flavor preservation and regulation of meat products during cold-chain circulation.