Qualidade da carne de bovinos superprecoces terminados em confinamento / Quality of meat from super-young cattle finished in feedlot

Avaliou-se a qualidade da carne de 10 bovinos F1 Guzerá-Nelore e 10 F2 Pardo Suíço-Guzerá-Nelore, inteiros, e abatidos precocemente. Na avaliação da carne, foi utilizado o músculo Longissimus dorsi. O delineamento experimental foi o inteiramente ao acaso. Verificaram-se para F1 e F2, respectivamente, médias para umidade de 75,3 e 75,1, extrato etéreo de 1,4 e 1,5, proteína de 23,7 e 23,6 e cinzas de 1,04 e 1,06. Cor em L* de 28,9 e 30,3, médias para cor em a* de 22,6 e 23,4 e cor em b* de 15,3 15,4, força de cisalhamento de 3,4 e 3,5, perda de peso pelo descongelamento de 9,8 e 10,5 e perda pelo cozimento de 15,9 e 15,6. Não houve diferença estatística para nenhuma das variáveis analisadas entre os grupos genéticos.

The purpose of this study was to use instrumental analysis to evaluate the chemical composition and fatty acid profile of 10 cattle Guzerath-Nellore (F1) and 10 Brown Swiss-Guzerath-Nellore (F2), intact and feedlot finished and slaughtered at 13 months. The Longissimus dorsi was used for meat evaluation. The experimental design was completely randomized. Humidity for F1 and F2 was respectively 75,3 and 75,1 averages, 1,4 and 1,5 averages for ether extract, proteins were 23,7 and 23,6 and 1,04 and 1,06 averages for ash. The results for F1 and F2, respectively, with averages for color to L * of 28,9 and 30,3, averages for the color to a* of 22,6 and 23,4 and color to b * 15,3 and 15,4, averages for shear force of 3,4 and 3,4, weight loss by thawing of 9,8 and 10,5 and weight lost by cooking of 15,9 and 15,4. There were no differences in genetic groups analysis.

The effects of anticalcification treatments and hydration on the molecular dynamics of bovine pericardium collagen as revealed by 13C solid-state NMR.

This article describes a solid-state NMR (SSNMR) investigation of the influence of hydration and chemical cross-linking on the molecular dynamics of the constituents of the bovine pericardium (BP) tissues and its relation to the mechanical properties of the tissue. Samples of natural phenethylamine-diepoxide (DE)- and glutaraldehyde (GL)-fixed BP were investigated by (13)C cross-polarization SSNMR to probe the dynamics of the collagen, and the results were correlated to the mechanical properties of the tissues, probed by dynamical mechanical analysis. For samples of natural BP, the NMR results show that the higher the hydration level the more pronounced the molecular dynamics of the collagen backbone and sidechains, decreasing the tissue's elastic modulus. In contrast, in DE- and GL-treated samples, the collagen molecules are more rigid, and the hydration seems to be less effective in increasing the collagen molecular dynamics and reducing the mechanical strength of the samples. This is mostly attributed to the presence of cross-links between the collagen plates, which renders the collagen mobility less dependent on the water absorption in chemically treated samples.

Effect of moisture content on the invertase activity of freeze-dried S. cerevisiae.

The invertase activity of intact Saccharomyces cerevisiae submitted to freezing-thawing was affected by pH, the chemical nature of the buffer, and the freezing cooling rate (CR), leading in some cases to a complete invertase inactivation (acetate buffer, pH 4.0, CR = 0.5 degree C/min). Once established under adequate freezing conditions the invertase activity remained unchanged after freeze-drying. Nevertheless, in some cases the cell-growing capability after freeze-drying diminished around 70%, mainly if the frozen cell suspension was attained through freezing carried out at CR = 0.5 degree C/min. Water sorption isotherms of freeze-dried samples (freeze-dryer Edwards L-4KR; 30 degrees C and 0.1 mB) were determined at 10 and 25 degrees C. The monolayer moisture content (MMC) at each temperature (12.7 and 3.71 for 10 and 25 degrees C, respectively) was calculated from isotherms by applying BET and GAB models. Freeze-dried yeast with water activity (Aw) between 0 and 0.33 (about the MMC value) maintained at 25 degrees C for 235 days and at 89 degrees C for 15 min retained at least 85% of its original invertase activity (IA), whereas samples with Aw > MMC lost at least 60% of its IA. X ray diffraction showed that the freeze-dried cake before and after storage presented an amorphous structure.

Efeito do valor de pH do meio na estabilidade da peroxidase e de carotenos de cenoura (Daucus carota L.). / Effect of pH on stability of peroxidase and of carotenes in carrot (Daucus carota L.)

Estudou-se a influencia do valor de pH do meio na atividade enzimatica da peroxidase e na estabilidade de beta-caroteno de cenoura fresca. Os valores de pH estudados foram de 4,0; 5,0; 6,0; 6,2; 6,4; 6,6; 6,8; 7,0 e 8,0.A atividade enzimatica maxima foi verificada na faixa de pH compreendida entre 6,0 e 6,4.O teor de beta-caroteno manteve-se inalterado para todos os valores de pH ensaiados