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This study was to evaluate the effects of two systems for US application on the physical (Warner Bratzler Shear force - WBS, and color) chemical (pH, lipid oxidation,) and microbiological (mesophilic, lactic acid and psychotropic bacteria) properties of Semitendinosus beef during storage (16 days at 7±1ºC). Samples obtained 48 h post-mortem were submitted to US using bath (45 kHz) and probe (20 kHz) in different time (0, 60, 120 or 240 s). After application the samples were vacuum packaged and evaluated during at 0, 3, 5, 9 and 16 days. The sonication presented an influence (P <0.05) in pH, wherein sonicated samples presented higher pH than the control up to 5th day of storage. US reduced WBS force after treatment, but this effect was not maintained during storage, even because cold storage improves toughness of meat. Lipid oxidation and color values did not changed and microbial flora were not damaged by the use of US. Discriminant analysis shows that storage time was the most important factor, while US system and time of exposure presented slightly differences regarding to their effect on meat. The results suggested that for improvement of US effect on meat the application should be performed not only before packaging, but also during storage. [ABSTRACT FROM AUTHOR]

In total, 2520 chickens were randomly allocated into 36 pens with 70 chickens per pen. One group that served as the control was fed a basal diet, while the others were fed diets supplemented with olive leaves at 5 or 10 g/kg. At 42 days of age, chickens were slaughtered and the breast was used in the manufacture of chicken hamburgers. The lipid and protein oxidation and bacterial count of chicken hamburgers were assessed. The results showed that the incorporation of olive leaves in chicken diets decreased (P < 0.05) the lipid and protein oxidation of chicken hamburgers during frozen storage. Dietary olive leaves at 10 g/kg were more effective (P < 0.05) in inhibiting lipid and protein oxidation. Diet supplementation with olive leaves resulted in lower (P < 0.05) aerobic mesophilic and psychrophilic bacteria, Staphylococcus spp. and Enterobacteriaceae counts over the entire storage period. [ABSTRACT FROM AUTHOR]