钙蛋白酶系统及其对肉嫩度的影响

钙蛋白酶系统作为影响肉嫩度的重要因素引起了科研人员的广泛关注。钙蛋白酶系统是高度可调的复杂系统，包括钙激活酶、钙激活酶抑制蛋白和钙激活酶激活蛋白，三者相互作用，共同调控宰后肉的嫩化。本文综述了钙蛋白酶系统的结构及功能，并在此基础上阐述了其影响肉嫩度的作用机理。     

钙激活酶与肌肉嫩化的研究

宰后肌肉嫩度的变化是在多种酶的协同作用下完成的,其中一个重要部分是钙激活酶,主要论述了钙激活酶对肌肉嫩化的作用机理、钙激活酶嫩化模型、氯化钙与肉的嫩化和影响钙激活酶活性的因素等方面的内容。     

钙蛋白酶系统磷酸化对肉嫩度的影响研究进展

嫩度是肉品食用品质中最重要的品质特性之一,钙蛋白酶系统在宰后成熟过程中对改善肌肉嫩度起到主要作用。研究表明,磷酸化修饰参与钙蛋白酶系统复杂的活性调控过程。本文概述了μ-/m-钙蛋白酶和钙蛋白酶抑制蛋白磷酸化研究的最新进展,根据它们的磷酸化对其结构和功能的影响,探讨钙蛋白酶系统磷酸化修饰对宰后肉嫩化的作用机制,并对其在肉品质中的应用研究进行展望。     

宰后肉的嫩化机制及其影响因素

宰后肉类的后期成熟和嫩化处理,是改善肉品质（嫩度）的关键环节。本实验阐述了影响宰后肉嫩度的因素（pH值、胶原蛋白和钙激活酶）和相关嫩化机理（有机酸、电刺激、盐类、外源酶和内源酶、超声波、高压和吊挂拉伸的嫩化机理）。     

巴西研究牛肉中的钙和钾含量对内洛尔牛嫩度的影响

<正>钙和钾是动物营养中的必需营养素,由于它们在细胞中的作用,其含量对肉的嫩度有一定影响。研究表明,由钙蛋白酶和钙蛋白酶抑制酶组成的蛋白水解系统需要钙离子的参与,是宰后骨骼肌嫩度的主要影响因子。而钾的含量与肌肉收缩有关,也会影响肉的嫩度。巴西的科学家通过对老化14 d的肉进行测试发现钾含量对WarnerBratzler剪切力具有正效应,这也就意味着钾的含量越高肉的嫩度就越低。另外,编码     

钙蛋白酶系统对肉的嫩化作用研究进展

肉的嫩度是肉品质的一个重要指标,严重影响肉的食用价值和经济价值.钙蛋白酶系统通过水解肌原纤维蛋白,在宰后肌肉嫩化中起着决定性的作用.综述钙蛋白酶系统(包含钙蛋白酶、钙蛋白酶抑制蛋白和钙蛋白酶激活蛋白3部分)对肉嫩化的作用机制和研究现状,并探讨研究前景.     

钙激活蛋白酶在肉成熟中的作用机理

与肉成熟有关的内源蛋白酶之一的钙激活蛋白酶类(Calpains),对该酶类的组成成分、存在位置、含量测定、提纯方法、活性测定、不同部位分布特点、宰后含量变化及自我水解的特点进行了详细说明,以了解对探索肉的成熟机理具有重要意义的钙激活蛋白酶类的作用机理。本文引用Titin、Nebulin、Dystzophin、Desmin、Troponin-T等等蛋白的宰后变化分析以说明钙激活蛋白酶促进肉成熟的作用机理。最后指出该酶研究疑问和研究意义。     

细胞凋亡对肌肉宰后嫩化的贡献

嫩度是肉品最重要的品质指标,而成熟是改善肉的嫩度的重要途径。肉成熟嫩化的原因普遍认为是肌细胞的细胞骨架降解造成的。目前,细胞骨架降解的机理研究方面报道较多的是钙激活酶系统、组织蛋白酶系统和蛋白酶体,而有关细胞凋亡酶在肉成熟中的作用国内外还鲜见报道。本文综述了宰后肌细胞内生理条件的变化,以及细胞可能选择的死亡方式,即凋亡;概述了能作为caspase酶家族底物的几类主要的肌细胞骨架蛋白;对常用的几类诱导细胞凋亡的细胞毒素进行了介绍;最后,对细胞毒素注射应用于宰后牛肉品质形成机理研究的潜在意义进行了探讨。     

钙激活酶对肉嫩度的影响

宰后肌肉嫩度的变化是在多种酶的协同作用下完成的,其中一个重要部分是钙激活酶。本文主要论述了钙激活酶的分子结构特征,影响酶活性的因素、以及对肌肉嫩化的作用机理等方面的内容。     

肉类嫩化的理论、方法及前景

近十多年来,肉类嫩化理论及加工工艺研究一直是肉品学科中的热点之一。了解肉的嫩化机理可以更好地加速肉嫩化的过程。嫩化技术为宰后嫩化技术和宰前嫩化技术。牲畜宰前肉的嫩化如适龄牲畜在出栏前,日粮中适当加入VD3、VE,或使牲畜适当运动。综述了电刺激、钙处理、外源酶处理、机械嫩化、pH处理、高压处理、冲击波处理等影响肉类嫩度与品质的因素及嫩化的技术理论和方法。     

Applied and Emerging Methods for Meat Tenderization: A Comparative Perspective

The tenderization process, which can be influenced by both pre‐ and post‐slaughter interventions, begins immediately after an animal's death and is followed with the disruption of the muscle structure by endogenous proteolytic systems. The post‐slaughter technological interventions like electrical stimulation, suspension methods, blade tenderization, tumbling, use of exogenous enzymes, and traditional aging are some of the methods currently employed by the meat industry for improving tenderness. Over the time, technological advancement resulted in development of several novel methods, for maximizing the tenderness, which are being projected as quick, economical, nonthermal, green, and energy‐efficient technologies. Comparison of these advanced technological methods with the current applied industrial methods is necessary to understand the feasibility and benefits of the novel technology. This review discusses the benefits and advantages of different emerging tenderization techniques such as hydrodynamic‐pressure processing, high‐pressure processing, pulsed electric field, ultrasound, SmartStretch^?, Pi‐Vac Elasto‐Pack® system, and some of the current applied methods used in the meat industry.     

响应面试验优化超声波辅助木瓜蛋白酶嫩化河蚌肉工艺

为解决河蚌肉的肉质粗韧问题,提高其食用品质,利用超声波辅助木瓜蛋白酶对其嫩化处理。通过Box-Behnken试验设计,建立了综合评分与超声功率、超声时间、木瓜蛋白酶质量分数之间的二次回归模型;确定超声波辅助木瓜蛋白酶嫩化河蚌肉的最佳工艺参数为木瓜蛋白酶质量分数6%、超声功率150 W、超声时间27 min,此时河蚌肉嫩化效果最佳。与木瓜蛋白酶、超声波、CaCl2嫩化效果相比,可溶性蛋白含量提高48%,硬度和咀嚼性分别降低63%和65%。     

Meat tenderization by proteolytic enzymes after osmotic dehydration

The treatment of proteolytic enzymes is one of the popular methods for meat tenderization. In this case, it is very important how to introduce the enzymes into the meat cut. This paper describes meat tenderization by dipping the meat cut in a solution containing proteolytic enzymes after contact-osmotic dehydration. After the dehydration of each piece of meat from culled cow for 18 h by contact-dehydration sheet, each sample was dipped for 3 h in a solution containing papain or proteinases from Aspergillus traditionally used for soysauce production in Japan. It was stored at 3～4°C for 24, 48 and 168 h, and subjected to texture measurement, sensory evaluations, biochemical analysis and histological observations. The penetration efficiency of the enzyme solution (of around 80%) after the contact-osmotic dehydration seemed to be sufficient. A marked decrease in hardness by texture measurements was observed in the meats treated with proteolytic enzymes and higher sensory scores for tenderness were observed in the meats treated with enzymes as compared with the untreated meat. The papain-treated meat received the highest score in tenderness, but the scores given to juiciness and taste were lower than that of the control. The rapid increases of the fragmentation of myofibrils from the enzyme-treated meat were observed at first 24 h of storage as compared with that of the control. Remarkable degradation of myosin molecule in the myofibrils from the enzyme-treated meats was observed on SDS-PAGE profiles. Considerable degradation of myofibrilar structure especially due to proteolytic removal of Z-lines, was observed among the myofibrils from enzyme-treated meats by electronmicroscopy. The remarkable deformation and disruption of honeycomb-like structure of endomysium were also observed in the meats treated with enzymes. From these results, it was shown that treatment after osmotic dehydration, was effective in tenderizing.     

超声波技术嫩化机理及其在肉制品中应用效果的研究进展

嫩度是评估肉制品品质的重要指标,提高嫩度有利于吸引消费者二次购买。传统物理嫩化技术虽广泛应用于肉及肉制品的嫩化加工,但在线应用差这一缺陷导致消费者接受度较低,因此推进了新兴物理嫩化技术的研究。其中,超声波作为一种高效节能、绿色环保、穿透力强的非热加工技术广泛用于肉制品的嫩化。本文综述了肉制品嫩化理论、嫩度主要影响因素以及超声波嫩化的基本原理,并从不同角度（肌纤维和结缔组织特性）阐述了超声波技术对肉制品嫩度的影响,为超声波技术在改善肉制品品质方面提供新思路和理论指导。     

MEAT TENDERIZATION: POSSIBLE CAUSES AND MECHANISMS. A REVIEW.

The postmortem meat tenderizing process is complex and not fully understood. The nature of changes associated with the improvement in tenderness and the exact mechanisms involved are still unknown. Based on relevant evidence, old and new, this review attempts to clarify the statement of our knowledge of these aspects. Of the different biochemical and ultrastructural changes occurring in meat, a key role of myofibril disruption taking place at the N₂-line level in meat tenderization has been emphasized. This may be ascribed to the action of lyosomal enzymes, especially cathespin B and L. However, all the changes thus far identified can be only explained by a synergistic action of lysosomal and calcium-dependent proteinases. Besides or together with proteolytic enzymes, weakening of myofibrils may also be mediated by the high ionic strength achieved in postmortem muscles. Both mechanisms possibly involved in the meat tenderizing process have been tentatively tested in relation with the large muscle variability in aging rate. It appears that some concepts are in conflict with the results presented. For instance, no direct relationship was found between aging rate and proteinase content of muscles.     

Contribution of postmortem muscle biochemistry to the delivery of consistent meat quality with particular focus on the calpain system

Tenderness has been repeatedly reported as the most important quality aspect of meat. However, a number of studies have shown that a significant portion of retail meat can be considered tough. As a consequence, a significant consumer segment is willing to pay a premium for guaranteed tender meat. However, apart from measuring the shear force, there is no reliable method to predict tenderness. Most of the branded meat programs therefore attempt to ensure eating quality by controlling some of the factors that affect tenderness. Meat tenderness is determined by the amount and solubility of connective tissue, sarcomere shortening during rigor development, and postmortem proteolysis of myofibrillar and myofibrillar-associated proteins. Given the effect of postmortem proteolysis on the muscle ultrastructure, titin and desmin are likely key substrates that determine meat tenderness. A large number of studies have shown that the calpain proteolytic system plays a central role in postmortem proteolysis and tenderization. In skeletal muscle, the calpain system consists of at least three proteases, μ-calpain, m-calpain and calpain 3, and an inhibitor of μ- and m-calpain, calpastatin. When activated by calcium, the calpains not only degrade subtrates, but also autolyze, leading to loss of activity. m-Calpain does not autolyze in postmortem muscle and is therefore not involved in postmortem tenderization. Results from a number of studies, including a study on calpain 3 knockout mice, have shown that calpain 3 is also not involved in postmortem proteolysis. However, a large number of studies, including a study on μ-calpain knockout mice, have shown that μ-calpain is largely, if not solely, responsible for postmortem tenderization. Research efforts in this area should, therefore, focus on elucidation of regulation of μ-calpain activity in postmortem muscle. Discovering the mechanisms of μ-calpain activity regulation and methods to promote μ-calpain activity should have a dramatic effect on the ability of researchers to develop reliable methods to predict meat tenderness and on the meat industry to produce a consistently tender product.     

Calcium and potassium content in beef: Influences on tenderness and associations with molecular markers in Nellore cattle

Calcium (Ca) and potassium (K) are essential nutrients in animal nutrition. Furthermore, the Ca content can influence meat tenderness because it is needed by the proteolytic system of calpains and calpastatins, major factors in postmortem tenderization of skeletal muscles. K content, which is needed for muscle contraction, can also affect meat tenderness. This study showed that K positively affects the Warner–Bratzler shear force (WBSF), measured at 14 days of meat aging, which means that higher levels of K are related to lower meat tenderness. Additionally, a significant effect (P ≤ 0.015) of a SNP in the calcium-activated neutral protease 1 (CAPN1) gene on Ca content was observed. Metal content in beef can affect not only nutritional values but also meat quality traits. Part of this effect may be related to variation in specific genes.     

Effects of elastase from a Bacillus strain on the tenderization of beef meat

The tenderization effect of a new elastase from Bacillus sp. EL31410 was investigated on beef meat. Meat tenderization was done by dipping the meat cut in a solution containing proteolytic enzymes after freeze-dehydration. It was found that a marination time of 4 h was enough for enzyme adsorption. The samples were treated for 4 h in different enzyme solutions and then was stored at 4 °C for 24, 48, 72 h, and subjected to texture measurement, sensory evaluations, biochemical analysis and histological observations. A marked decrease in hardness, by texture measurements, was observed in the meats with papain and elastase and higher sensory scores for tenderness were observed in the meats treated with enzymes than in the control. The papain-treated beef meat received the highest score for tenderness, but the scores given for juiciness and taste were lower than that of the control. Rapid increases of fragmentation of myofibrils from the enzyme-treated meat were observed in the first 24 h of storage, especially for papain-treated meat. Meantime, elastin of myofibrilar structure was selectively degraded by elastase compared with the control when stored at 4 °C for 48 h as shown by electron microscopy. These findings suggest that Bacillus elastase (EL31410) is a promising substitute for papain as a favourable meat tenderizer.