Effect of postmortem aging and fast-freezing on meat quality of various lamb cuts under prolonged frozen storage and repeated freezing/thawing conditions

Abstract

This study aimed to investigate the effects of aging and fast-freezing on meat quality attributes of various lamb cuts under conditions of prolonged frozen storage (Experiment 1) and repeated freezing/thawing cycles (Experiment 2). The paired lamb muscles including longissimus dorsi, gluteus medius, quadriceps femoris, semimembranosus, and biceps femoris from 15 lamb carcasses were collected at 1 d postmortem. In Experiment 1, the muscles were vacuum-packaged and randomly assigned to one of 3 treatments: (1) non-frozen control (aged only for 5 wk at −1.5°C); (2) aging for 4 wk, fast-frozen in a −18°C glycol immersion chamber, and frozen storage in −18°C for 1 week; or (3) aging for 4 wk, fast-frozen, and frozen storage for 24 wk. In general, regardless of muscle cuts, samples that were aged, fast-frozen, stored for 1 wk, and thawed exhibited similar water-holding capacity, shear force, and color attributes as those of the aged-only (never frozen) lamb muscles (P>0.05). Furthermore, extending the frozen storage duration up to 24 wk did not result in any adverse effects on color, shear force, purge loss, or microbiological attributes of the aged/fast-frozen/thawed lamb muscles (P>0.05). In Experiment 2, the repeated freezing and thawing of aged and fast-frozen lamb loins (n=8) had no adverse impacts on color, tenderness, or microbiological attributes (P>0.05), although slight increases in purge and cook losses were observed compared to non-repeated slow-frozen loins. The findings of the present study suggest that the combined treatment of aging and fast-freezing can minimize changes in meat quality during the freezing and thawing process, even with prolonged frozen storage of up to 24 wk.