多频复合超声真空煮制对卤牛肉肌纤维结构及保水性的影响

Effect of Multifrequency Ultrasonic-Assisted Vacuum Cooking on the Muscle Fiber Structure and Water-Holding Capacity of Stewed Marinated Beef

以牛腱子肉为研究对象,对比不同复合超声频数(40/52/68、40/52、40/68、52/68、40、52、68、0 kHz)处理后卤牛肉纤维结构、质构特性和水分变化,探讨多频复合超声真空煮制对卤牛肉纤维结构以及保水性的影响。结果表明,随着复合超声频数的增加,肌原纤维小片化指数、β-转角与无规卷曲结构含量均随之增加,质构特性中弹性有增大趋势,而α-螺旋和β-折叠结构的相对含量、卤牛肉的硬度、咀嚼性、内聚性则随之降低,肌纤维表面结缔组织的溶解性增加,肌纤维分离、断裂愈加明显;低场核磁共振分析结果表明,超声处理使横向弛豫时间T2向左迁移并缩短,改变了水分分布,左迁幅度随复合超声频数增加而增大,结合水和自由水含量亦随之增加,准结合水含量相应减少;三频组蒸煮损失率显著低于双频和单频组,出品率的趋势则相反,三频出品率最高。综上,超声处理对卤牛肉肌纤维结构的破坏和保水性改善具有明显的频率效应,复合超声频数越多,频率效应越显著。

The effect of multifrequency ultrasonic-assisted vacuum cooking on the muscle fiber structure and water-holding capacity of stewed marinated beef was studied.Changes in the muscle fiber structure,texture properties and moisture content of stewed marinated beef prepared from beef shank under different ultrasonic frequencies(40/52/68,40/52,40/68,52/68,40,52,68 and 0 kHz)were measured.The results showed that with increasing the number of ultrasound frequencies,myofibrillar fragmentation index(MFI),the contents ofβ-turn and random coil increased,and the texture attribute of elasticity tended to increase,while the contents ofα-helix andβ-sheet decreased,and so did the hardness,chewiness,and cohesiveness of stewed marinated beef.Meanwhile,the solubility of connective tissue on the surface of muscle fibers increased,the separation and fracture of muscle fibers became more apparent.Low field-nuclear magnetic resonance(LF-NMR)results showed that ultrasound treatment caused a leftward shift of the transverse relaxation time(T2)and shortened it,thus changing the water distribution.As the number of ultrasonic frequencies increased,the shifting range of transverse relaxation time to the left increased,and the contents of bound water and free water also increased,while the content of quasi-bound water correspondingly decreased.Cooking loss was significantly lower in the triple-frequency group than in the dual-frequency and single-frequency groups,while the product yield showed an opposite trend,the highest value being found in the triple-frequency group.In summary,ultrasound treatment destroyed the muscle fiber structure and improved the water-holding capacity of stewed beef;the more the number of ultrasonic frequencies,the more pronounced the effect.