ABSTRACT
The effect of cooking on pH, juiciness, instrumental colour and microstructural properties of chicken breast meat was investigated. Industrial skinless chicken breast meat samples were purchased, frozen and sliced into dimensions , thawed and cooked by air frying (AF), baking (BK), deep fat frying (DF) and grilling (GR) at 170, 180 and 1900C for 0, 4, 8, 12 and 16 min. The pH value of the cooked samples increased from 6.05 to 6.25. Cooking methods, temperatures and times each resulted to increase in pH. The results of objective sensory instrumental analyses showed that cooking decreased significantly (p < 0.05) juiciness of cooked chicken breast meat. Samples cooked by BK had the highest juiciness value of 24.91%, while DF cooked samples had the least value of 13.89%.The instrumental analyses increased L*, a*, b* values and browning index. The temperature and time of cooking showed similar effects on juiciness and instrumental colour. Short cooking time (8 min) and 1700C resulted in higher juiciness and best appetizing appearance to the consumers. The microstructure studies showed that raw chicken breast meat had an intact muscle fibres and bundles, but cooking caused disintegration of muscle fibres, perimysial – collagen shrinkage and it resulted to drier samples with big cracks/ voids and big surface damages, particularly in AF, BK and GR cooked products at 1900C for 8 min.
ABSTRACT
Avaliaram-se a composição física da carcaça e a qualidade da carne de 22 novilhos contemporâneos, com média de idade de 22 meses, das raças Charolês ou Nelore, terminados em confinamento, e que receberam diferentes proporções de concentrado na dieta. A fração volumosa da dieta foi composta pelas silagens de milho e sorgo em partes iguais. Os animais foram distribuídos em três tratamentos constituídos por 35, 50 ou 65 por cento de concentrado na matéria seca. Não houve efeito (P>0,05) da porcentagem de concentrado na dieta sobre a composição física da carcaça. A proporção de inclusão do concentrado influenciou (P=0,0013) positivamente a maciez da carne, aumentando em 0,026 pontos a cada ponto percentual de aumento do concentrado. As demais características qualitativas da carne não foram influenciadas (P>0,05) pelo aumento do concentrado na dieta. A carne dos novilhos Charolês apresentou textura mais fina, 4,15 x 3,14 pontos, foi mais macia, 6,85 x 5,71 pontos, mais suculenta, 7,17 x 5,77 pontos, e apresentou menor resistência das fibras ao cisalhamento, 3,79 x 5,79kgF. A carcaça dos novilhos Charolês apresentou maior deposição muscular, 65,5 x 61,5 por cento, e a dos novilhos Nelore apresentou maior percentagem de gordura, 23,3 x 20,3 por cento.
The physical compositionof carcass and meat quality of 22 Charolais (C) and Nellore (N) steers, feedlot finished and fed different levels of concentrate in the diet, were evaluated. The roughage fraction of the diet was made up by equal parts of corn and sorghum silages. The animals were distributed in three treatments constituted by 35, 50, or 65 percent of concentrate, in dry matter basis. Concentrate level did not affect carcass physical composition (P>0.05). Meat tenderness was positively affected (P=0.0013) by the concentrate level, increasing 0.026 points for each percent point increase of concentrate. The other meat qualitative characteristics were not affected by the concentrate level in the diet (P>0.05). Charolais steers showed meat with lighter color (4.44 x 2.89; P=0.0013), finer texture (4.15 x 3.14 points), better tenderness (6.85 x 5.71 points; P=0.0010), higher juiciness (7.17 x 5.77 points), lower Shear force (3.79 x 5.79kgf), and carcasses with higher muscle deposition (65.5 x 61.5 percent) in relation to N steers. Carcasses of Nellore steers showed higher fat percentage (23.3 x.20.3 percent).