| Tenderness is an important indicator of beef eating quality. The early chilling temperature before rigor stage has an important influence on the tenderness and proper chilling can inhibit the growth of microorganisms on the surface of beef, prolong storage time, slow down denaturation of muscle protein, and it also promote the maturation process, which can improve the degree of tenderness.After cooling process, off rigor is still needed under proper temperature to make the beef tender. Temperature can directly affect the speed of off rigor, so it is feasible to accelerate the process of off rigor by controlling the mature temperature.Under traditional storage temperature of chilled meat, shelf life is short, microorganisms grow fast, so the impact of freezing temperatures on beef quality was studied, which is helpful to solve the problem of short storage time and rapidly declining of edible quality.In this study, cuts of beef (length × width × height= 15.0cm×10.0cm5.0cm) were chosen for the test material, different cooling type of pre-rigor stage,cooling ice storage and different maturity temperature were researched. The results are as follows:1 Effect of different pre-rigor chilling on quality Characteristics of cuts beefrapid chilling, conventional chilling and delayed chilling process were used in this study.The core temperature, pH,water retention, color, shear force and orther indicators were tested to study the influence of different cooling types. With rapid chilling and conventional cooling, chilling speed was fast,and before the temperature was 4℃, pH value was high, cold muscle shrunk, the tenderness of the meat had a significant effect (P<0.05), but there was had no significant effect on color (P>0.05). The falling speed of the meat temperatures was much lower using delayed chilling method, which can to advance into the stiffness of beef, with the maturity will be increasing beef tenderness, brightness and redness are improved, although the chilling loss more rapid cooling of large beef, but beef tenderness maximum degree of improvement, the best eating quality of beef. So that the delay was cooled to stiff preliminary cuts of beef the best chilling.2. Effect of maturation temperature on beef cuts qualityBeef cuts matured at (4±0.5)℃、(10±0.5)℃, As for the hot mature, discharge of acid was completed after 5d slaughter, and beef tenderness improved significantly (P<0.05), water retention was also significantly higher than the low temperature mature, but beef color differences among mature temperature was not significant. From the mechanism of the tenderness, calcium-activated enzyme declined in the maturation process, enzyme activity stored at (10±0.5)℃ was higher than that of (4±0.5)℃, which can promote the process of mature and improve the tenderness. Myofibrillar fragmentation index was significantly different (P<0.05). Collagen content of two proven temperature was not significantly different (P> 0.05), little effect on the maturation process. Therefore, It is suggested that 10℃ high temperature can promote maturation, improve meat tenderness, and has a high water retention.3 Effect of ice temperature storage on the quality of chilled beefThe beef were storged in three different temperatures (-1.5±0.5)℃, (0± 0.5)℃,and (4±0.5)℃, the effects of storage temperature on beef sensory quality, texture features, color and water holding capacity and other indicators of quality were studied. The results showed that:at ice temperature storage conditions, it can extend the shelf life of beef to more than 24 days effectively, and the effective shelf of beef was 8 days,16 days when storged at 4℃ and 0℃, respectively. At ice temperature conditions, when the shelf life of beef up to 24 days, the total number of beef colonies was 2.6×106cfu/g, and the TVB-N content was 14.56mg/100g, they are within the scope of the national secondary standard meat; pH value of 6.14 was still within standard range of first class fresh meat, and water loss rate was significantly lower than that of stored at (0±0.5)℃ and (4±0.5)℃. Color was red and there is no decay smell, belonging to the standard of fresh meat. In this way, market supply of fresh beef can be effectively extended and the decay loss rate declined, which can meet people’s demand for safety and healthy animal food. |
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