Combined effects of gamma irradiation and aging on tenderness and quality of beef from Nellore cattle.

Combined effects of gamma irradiation (0, 3, 6 and 9 kGy) and aging (1 and 14 days) on quality attributes of vacuum-packaged beef from Nellore cattle were evaluated. The meat water holding capacity was affected by irradiation, increasing (p < 0.05) purge and cooking loss regardless of the dose used. Irradiation negatively affected myofibrillar fragmentation, but samples irradiated at 9 kGy had (p < 0.05) higher soluble collagen and lower shear force values. The meat metmyoglobin reducing activity was reduced (p < 0.05) by the irradiation process, inducing the metmyoglobin accumulation with increasing dose applied. Samples irradiated at 9 kGy presented (p < 0.05) higher lipid oxidation and lower oxymyoglobin proportion and color redness and chroma values. It was concluded that irradiation at 9 kGy combined with aging can be used as an effective tool for improving the tenderness of Nellore beef, but resulted in a discoloration of the beef.

Retail display of beef steaks coated with monolayer and bilayer chitosan-gelatin composites.

The effects of edible monolayer and bilayer chitosan-gelatin coatings on the weight loss, lipid oxidation, color preservation (display-life), and shelf-life of beef steaks during 10 days of retail display (at 4 °C; 12 h light/day) were evaluated. The edible coatings had a homogeneous crack-free surface, with the bilayer films being two times thicker than the monolayer coatings. During storage, the control samples had higher pH values and more weight loss (P < .05) than the coated ones. The coatings effectively retarded (P < .05) lipid oxidation and microbial growth (psychrotrophic bacteria, molds, and yeast), extending the shelf-life from 6 to 10 days. The coatings also significantly prevented metmyoglobin accumulation on the beef surface, as reflected in the maintenance of the CIE color indices and sensorial redness perception throughout storage. These effects were similar for both the monolayer and bilayer films, suggesting that chitosan-gelatin coatings could improve the shelf-life and display-life of beef during retail storage.