Efeitos da radiação gama e do congelamento prévios à maturação na cor e perfil de ácidos graxos da carne bovina

Abstract

The objective of this study was to evaluate the effects of gamma radiation and freezing prior to aging on the color and fatty acid profile of beef. Different irradiation doses (0, 3, 6 and 9 kGy) were applied in frozen (-18 ° C / 24 h) and non-frozen (4 ° C) samples of left and right Longissimus thoracis et lumborum, of Nellore (Bos indicus) and then aging (1 ° C) for 1 and 14 days. The frozen samples were thawed (4 ° C / 24 h) before aging. The samples were evaluated for pH, oxygen consumption rate (TCO), metamioglobin reducing activity (MRA), proportion of heme pigments, and instrumental (CIELAB) and sensorial color. The non-aging samples were also evaluated for lipid oxidation (thiobarbituric acid reactive substances - TBARS and peroxide index - PI) and fatty acid profile. The pH values of the samples submitted to freezing reduced (P <0.05) after 14 days of aging. The freezing process reduced (P <0.05) the TCO values only on the first day of aging and the MRA values at both times. The MRA of the non-frozen samples reduced (P <0.05) with the application of higher doses of irradiation. Higher irradiation doses resulted in a greater reduction (P <0.05) in the proportion of oximioglobin in the frozen samples than in the non-frozen ones. The proportion of metamioglobin increased (P <0.05) with higher irradiation doses and aging time. Higher irradiation doses reduced the color tone values of the frozen samples (P <0.05), but did not affect (P> 0.05) the color of the non-frozen samples. Consumers perceived the non-frozen samples irradiated by 9 kGy as lightness samples regardless of aging time. Higher doses of irradiation implied (P <0.05) higher values of TBARS and frozen samples in lower (P <0.05) PI values. A reduction (P <0.05) was observed in the content of unsaturated fatty acids, especially in the omega 3 series, with the application of higher doses of gamma radiation. It was concluded that gamma radiation and freezing caused changes in the proportion of heme pigments in the meat, with little effect on the instrumental color and with an increase in the perception of light color. The irradiation implied an increase in the lipid oxidation of the meat, with consequent reduction in the unsaturated fatty acids.