钙蛋白酶和肉的成熟嫩化

对钙蛋白酶(Calpain)及其与肉的成熟嫩化的关系作一概述，认为在肉的成熟嫩化过程中。钙蛋白酶和溶解体组织蛋白酶起着巨大的作用，而钙蛋白酶的作用更为显著。     

梅山猪与三元杂交猪肌内脂肪含量、μ-钙蛋白酶和蛋白降解对嫩度的影响

目的:比较梅山猪与三元杂交猪(杜洛克猪×长白猪×大白猪)的剪切力、肌内脂肪含量、μ-钙蛋白酶及蛋白降解的差异,分析影响梅山猪肉嫩度的因素。方法:选取6头纯种梅山猪和6头三元杂交猪,取背最长肌为实验材料,采用变性聚丙烯酰胺凝胶电泳和蛋白免疫印迹技术测定μ-钙蛋白酶在宰后45 min的降解和整联蛋白、伴肌动蛋白在宰后成熟1、3、7 d的降解情况。结果:梅山猪肉在宰后成熟1、3、7 d的剪切力值均显著低于三元杂交猪(P0.05),在宰后成熟1 d的肌内脂肪含量显著高于三元杂交猪(P0.05)。在宰后45 min,梅山猪的μ-钙蛋白酶的80 kD百分含量显著高于三元杂交猪,78 k D和76 kD百分含量显著低于三元杂交猪(P0.05),梅山猪的μ-钙蛋白酶的自我降解程度较低,这与梅山猪的蛋白降解情况相一致。梅山猪的整联蛋白在成熟3d的相对光密度值显著高于三元杂交猪(P0.05),宰后成熟3 d和7 d的降解率显著低于三元杂交猪(P0.05),伴肌动蛋白在成熟1 d和3 d的相对光密度值显著高于三元杂交猪(P0.05)。结论:梅山猪的整联蛋白和伴肌动蛋白降解较少,这与μ-钙蛋白酶的降解有关,而μ-钙蛋白酶和蛋白降解对梅山猪肉的嫩度影响不大,梅山猪肉相对较高的肌内脂肪含量解释了其较高的嫩度。     

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。     

梅山猪与三元杂交猪肉宰后成熟过程品质变化比较

目的：比较梅山猪与三元杂交猪的肉品质以及影响两个猪种持水力的因素,为梅山猪肉质性状的选择提供一定的参考。方法：选取6 头梅山猪和6 头三元杂交猪,在宰后45 min取胴体左侧背最长肌,采用低场核磁共振技术测定肌肉中水分分布情况以及酪蛋白酶原分析法测定钙蛋白酶的活性,在成熟过程中的1、3、7 d测定肌肉的持水力。结果：梅山猪肉色的L*值和a*值与三元杂交猪差异显著（P＜0.05）。梅山猪宰后成熟1、3 d的贮藏损失率和宰后1 d的蒸煮损失率显著低于三元杂交猪（P＜0.05）,说明梅山猪肉具有较高的保水性。梅山猪宰后45 min的pH值显著高于三元杂交猪（P＜0.05）。低场核磁共振T2弛豫测定结果表明,梅山猪肉中结合水含量显著高于三元杂交猪,自由水含量显著低于三元杂交猪（P＜0.05）。肌肉水分分布的差异在一定程度上解释了两种猪肉的持水力的变化。梅山猪与三元杂交猪肉中的钙蛋白酶活性在成熟第1天差异显著（P＜0.05）,成熟第3天和第7天差异不显著。结论：钙蛋白酶活性对这两个猪种的保水性影响不大,肌肉的水分分布及宰后45 min、pH值的差异解释了梅山猪具有较高的保水性。     

内源蛋白酶在肉嫩化中的作用(综述)

本文阐述了与肉成熟有关的两类蛋白酶,即钙激活蛋白酶和溶酶体组织蛋白酶,并分别就两类酶的分类、影响酶活性的因素、在肉嫩化中的作用、分离提纯及活性测定方法等作了介绍.     

钙蛋白酶系统对肌肉系水力的影响研究进展

系水力是肉品质评价过程中重要的指标之一。大量的研究表明,系水力与宰后肌肉蛋白质的降解有关,而钙蛋白酶系统在此过程中起着重要的调控作用。本文结合国内外关于钙蛋白酶在肌肉系水力方面的研究,概述了系水力、钙蛋白酶系统,及其钙蛋白酶对系水力影响的可能作用机制,旨在为今后其在该领域的进一步研究提供参考。     

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.     

钙蛋白酶的活性调节及其与肉嫩度的关系

钙蛋白酶(calpain)是与肉嫩度相关的重要内源性蛋白酶之一,广泛存在于细胞质中,且需要一定量的Ca2 激活。研究表明,钙蛋白酶在Ca2 的激活下能降解肌原纤维蛋白,从而改善肉品嫩度。但是,由于钙蛋白酶抑制蛋白(calpastatin)等因素对钙蛋白酶活性的抑制作用,钙蛋白酶的活性调节成为一系列高度可调的复杂过程。在综述钙蛋白酶结构与功能关系的基础上,进一步阐述了钙蛋白酶的活性调节如何影响肉品嫩度。     

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。     

生姜蛋白酶对猪肉致嫩作用的研究

本课题研究了生姜蛋白酶对猪肉的致嫩作用,对其用量、pH值、预处理温度进行了测试对比。结果表明:生姜蛋白酶对猪肉的致嫩作用十分显著,最佳用量为0.01%,最佳pH为7.0,最佳预处理温度为30℃。     

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。     

Role of muscle endopeptidases and their inhibitors in meat tenderness

Postmortem meat tenderness improvement is generally assumed to result from the softening of the myofibrillar structure by endogenous proteolytic enzymes. In this context, the present paper is a broad overview of the different peptidases so far identified in skeletal muscle, their specific inhibitors and their respective potential role in postmortem muscle. A series of petidase families have been thus considered including calpains, cathepsins, proteasomes, caspases, matrix metallopeptidases (MMP) and serine peptidases.     

Trends in postmortem aging in fish: understanding of proteolysis and disorganization of the myofibrillar structure

Postmortem tenderization is caused by enzymatic degradation of key structural proteins in myofibrils as well as in extracellular matrix, and of proteins involved in intermyofibrillar linkages and linkages between myofibrils and the sarcolemma. The function of these proteins is to maintain the structural integrity of myofibrils. Current data indicate that calpains and cathepsins may be responsible for degradation of these proteins. Other phenomena occurring in cells postmortem (pH drop, sarcoplasmic Ca2+ increase, osmotic pressure rise, oxidative processes) may act in synergy with proteases. Our understanding of the underlying mechanisms of muscle degradation should be improved for an accurate evaluation of the postmortem muscle changes and consequently of the fish quality.     

Survey of conditioning indicators for pork loins: changes in myofibrils, proteins and peptides during postmortem conditioning of vacuum-packed pork loins for 30 days

This study was performed to examine the changes in myofibrils, proteins and peptides during postmortem conditioning of vacuum-packed pork loins at 4 °C for 30 days. The fragmentation of myofibrils has been observed during postmortem aging for 20 days and its ratio increased until 20 days. The 32 kDa component derived from troponin T increased during storage for 20 days, while a glyceraldehyde 3-phosphate dehydrogenase (GAPDH) among sarcoplasmic proteins was significantly degraded during storage for 15 days. Some oligopeptides increased during such storage, two peptides (peptides P1 and P2) significantly increasing during storage for 20 days. Their sequences were APPPPAEVHVHEEVH (P1) and VPTPNVSVVDLT (P2). Homology analysis showed that peptides P1 and P2 were derived from troponin T and GAPDH, respectively. It was concluded that the fragmentation of myofibrils, the increases in the 32 kDa component and peptides P1 and P2, and the decrease in GAPDH were useful as conditioning indicators of progressive degree during the storage of pork loins stored at 4 °C.     

Bovine muscle 20S proteasome. II: Contribution of the 20S proteasome to meat tenderization as revealed by an ultrastructural approach

The role of the 20S proteasome proteolytic effects was revisited using an ultrastructural approach with the aim to explain some particular structural changes identified in type I muscles and in high pH meat. In both types of meat, major changes observed after ageing are an increase in the thickness of the Z-line followed by the appearance of an amorphous protein structure spreading out over the I-band. This was followed by a total degradation of this amorphous structure and of the Z-line. Partial transversal fragmentation of the myofibrils within the I-band can also be detected. The data reported clearly demonstrate that the 20S proteasome was able to mimic these sequential structural changes, a feature never obtained with either calpains or cathepsins. It is the first time that a direct implication of this complex in postmortem muscle is postulated.     

Preliminary study on the effect of caspase-6 and calpain inhibitors on postmortem proteolysis of myofibrillar proteins in chicken breast muscle

The objective was to determine the effect of three different protease inhibitors, caspase-6 specific inhibitor VEID-CHO (N-Acetyl-Val-Glu-Ile-Asp-al), calpain inhibitor leupeptin or calpain inhibitor EGTA on protein degradation, ultrastructure of myofibrils and calpain activity during postmortem (PM) aging of chicken muscle. Results showed that proteolysis of nebulin, troponin-T and desmin during 14-days postmortem storage were inhibited significantly by leupeptin. Inhibitive effects of VEID-CHO and EGTA on these protein degradations were significant only during 1-day postmortem storage. The activities of calpains were inhibited noticeably by leupeptin and EGTA, but not by VEID-CHO. Samples treated with VEID-CHO, leupeptin and EGTA retarded structural disruption of chicken muscle fibers. These results demonstrate that calpain is a major contributor to PM tenderization; while caspase-6 plays, if any, a minimal role in the conversion of chicken muscle to meat.     

Effect of low voltage electrical stimulation and temperature conditioning on postmortem changes in glycolysis and calpains activities of Korean native cattle (Hanwoo)

The combined effects of low voltage electrical stimulation (LVES) and temperature conditioning during early postmortem (PM) ageing on glycolytic rates and calpains activities of Korean native cattle (Hanwoo) were determined. M. longissimus was taken after splitting course, divided into three pieces and temperature conditioned at 2, 16, and 30°C for 3 h PM. The PM glycolytic rates, calpains and calpastatin activities were measured at 1, 3, 9, and 24 h PM. Although both LVES and the 30°C treatment accelerated glycolytic rates and resulted in improved enzyme activities, LVES was more effective for the improvement of enzyme activities than the 30°C treatment. Among tested Rigor-values (R-value; R(248), R(250), and R(258)), R(258) showed the highest correlation with pH (r=0.814, P<0.01), glycogen content (r=0.784, P<0.01) and μ-calpain (r=0.838, P<0.01) and selected as a suitable parameter to predict glycolytic rate. The high correlation coefficients between μ-calpain activity and metabolic rate parameters suggest that the change in the enzyme activity is closely related to glycolytic rates. The LVES in combination with the 30°C treatment until 3 h PM was the best treatment to accelerate the glycolytic rate and to improve the calpains activities in Hanwoo tissue.     

The effects of different chilling methods on meat quality and calpain activity of pork muscle longissimus dorsi

The objective of this study was to investigate the effects of conventional chilling (0 to 4 °C), rapid chilling (RC, -20 °C for 30 min, followed by 0 to 4 °C), and short-duration chilling (0 to 4 °C for 30 min, followed by 25 °C) on meat quality and calpain activity of pork muscle longissimus dorsi (LD). The muscle quality characteristics pH, color, cooking loss, pressing loss and tenderness, and calpain activities were measured 0-, 3-, 12-, and 24-h postmortem. Results show that the RC resulted in a faster temperature decline of the muscle, and prevented the meat pH and Commission Internationale de l'Eclairage L* value from declining during postmortem aging. RC also reduced meat cooking loss and pressing loss compared with the other two chilling methods. However, the chilling methods did not significantly affect meat shear force. During the first 24-h postmortem, there was not a noticeable change in the activity of m-calpain. But μ-calpain activity decreased regardless of chilling method. In the rapidly chilled carcasses, μ-calpain activity remained the same 3- and 12-h postmortem. However, in the short-duration chilled and conventionally chilled carcasses, the activity was visibly reduced. At 24-h postmortem, no clear zones on the gel were observed in all three treatments. PRACTICAL APPLICATION: Conventional and RC methods are commonly used for pork in commercial practice nowadays. Compared with conventional chilling, the effect of RC on quality parameters of pork varies. In recent years, short-duration chilling (SC) is widely used in many Chinese pig slaughtering facilities. However, few researchers have studied the effect of SD on pork quality. Therefore, the present study investigated the effect of different chilling methods on functionalities or quality of chilled pork meat.     

肌肉内源蛋白酶及其在干腌火腿加工过程中的作用

综述了组织蛋白酶和钙激活中性蛋白酶的性质、水解能力、抑制剂及其影响因素的研究进展 ,并对国外就其在干腌火腿加工过程中的活性变化及其与火腿加工质量关系的研究结果进行了总结 ,有助于我国正在进行的传统肉制品加工工艺现代化改造