The effect of increased methionine in broiler chicken diets on the quality of breast muscles at different times of vacuum storage under refrigeration

The aim of the study was to determine the effect of different levels of DL-methionine in feed for broiler chickens on the quality of vacuum-packed breast muscles stored under refrigeration. The material for the study was 72 breast muscles from 35-day-old broiler chickens fed diets with varying content of DL-methionine. The control group received a basal diet without additional DL-methionine, while the experimental groups received compound feeds supplemented with 0.08% or 0.24% DL-methionine. At 35 days of age, 24 birds from each group were randomly selected and experimentally slaughtered. After the carcasses were dissected, 8 right breast muscles were selected from each feeding group and analysed immediately after cooling. The remaining muscles were vacuum-packed and after 7 and 14 days of storage physicochemical and sensory analyses were performed to assess the influence of storage time on changes in their quality. The methionine level was not found to affect the sensory properties of the breast muscles, but the meat of birds receiving a higher level of this amino acid had better shear force and water-holding capacity in comparison to the control group. After just 7 days, the results of the analyses of vacuum-packed refrigerated muscles showed a negative effect of storage time on the capacity of the muscle tissue to bind water, as well as changes in the proportion of red colour in the muscles. However, it is worth noting that the sensory quality of the muscles deteriorated only after 14 days of storage.