不同地区羊肉肌内结缔组织特性的分析

采用了冬夏季蒙古羊-自然,乌珠穆沁羊-自然和乌珠穆沁羊-圈养羊的半腱肌和肱三头肌为研究对象,利用分光光度法测定样品结缔组织中的胶原蛋白的含量及其热溶解性。结果表明:3个品种羊不同季节屠宰后其半腱肌和肱三头肌中结缔组织的胶原蛋白含量最高,肌内膜胶原蛋白含量明显高于肌束膜中胶原蛋白含量。其中,半腱肌中的结缔组织的胶原蛋白含量分别均呈现显著下降趋势(p0.05),但是同一种羊冬、夏两季间半腱肌中的结缔组织的胶原蛋白含量变化不显著,同一季节屠宰的3个品种羊半腱肌的结缔组织、肌内膜、肌束膜中胶原蛋白含量均呈现显著差异(p0.05)。肱三头肌的结缔组织、肌内膜中胶原蛋白含量均呈现显著差异(p0.05),夏季乌珠穆沁羊-自然与圈养的肱三头肌中胶原蛋白含量变化不显著。3个品种羊不同季节的羊半腱肌和肱三头肌结缔组织内胶原蛋白热溶解性存在显著差异(p0.05),夏季半腱肌结缔组织内胶原蛋白热溶解性高于冬季半腱肌,冬季肱三头肌结缔组织内胶原蛋白热溶解性明显高于夏季。蒙古羊-自然的结缔组织内胶原蛋白热溶解性明显高于乌珠穆沁羊。     

乌珠穆沁羊生长过程中肌内结缔组织特性研究

以1～18 月龄乌珠穆沁羊为研究对象,分别利用羟脯氨酸法和DSC 法研究其生长过程中肌内结缔组织中胶原蛋白含量、胶原蛋白热溶解性及其热变性的变化。结果表明：结缔组织、肌内膜和肌束膜中胶原蛋白含量和热溶解性随着月龄的增加而显著下降(P ＜ 0.05),而且肌内膜中胶原蛋白含量和热溶解性明显高于肌束膜。结缔组织和肌内膜胶原蛋白的热变性温度随着月龄的增加而逐渐升高,肌束膜胶原蛋白的热变性温度随着月龄的增加而呈现下降趋势。     

乌珠穆沁羊生长过程中肌内结缔组织结构及特性变化

以优良品种乌珠穆沁羊(1～18月龄)为研究对象,利用组织学法观察其生长过程中肌肉结缔组织的结构变化,并对其生长过程中肌内结缔组织中吡啶诺林含量和蛋白多糖中糖醛酸含量进行测定分析。结果表明：肌内膜的厚度随着月龄的增加而增加,其中6月龄与9月龄、12月龄与18月龄之间差异不显著(P＞ 0.05);而肌束膜厚度1～6月龄显著增加,之后显著下降(P＜0.05)。肌内膜的蜂窝孔径逐渐增大,并且胶原纤维网状结构变的越紧密,肌束膜中胶原纤维的波浪状结构变的越有规则。结缔组织内吡啶诺林含量和糖醛酸含量随着月龄的增加而逐渐增加,各月龄之间差异均显著(P＜0.05)。     

屠宰季节对蒙古羊肌内结缔组织含量及热变性温度影响研究

以不同屠宰月份自然放养的蒙古羊的半腱肌和肱三头肌结缔组织为研究对象,利用差示扫描量热仪DSC(Different Scanning Calorimeter)测定肌内结缔组织中胶原蛋白的热变性温度,结果如下:相同屠宰月份半腱肌中结缔组织含量高于肱三头肌;半腱肌和肱三头肌中结缔组织含量除5月和8月间变化不显著外其余均显著(p0.05)。8月结缔组织含量最低,11月最高。肱三头肌结缔组织的热变性温度高于半腱肌;11月屠宰样品中半腱肌结缔组织的热变性温度Td最高。而肱三头肌结缔组织的热变性温度Td在5月屠宰样品中最高。解释了自然放养蒙古羊不同部位骨骼肌内结缔组织特性在不同月份的变化规律,在此基础上为屠宰月份变化,而引起结缔组织的特性变化机理提供理论依据。     

来自牛半腱肌肌束膜和肌内膜胶原蛋白热力学特性分析

探讨牛半腱肌肉肌束膜和肌内膜胶原蛋白热力特性的热诱导变化。牛半腱肌肉分别采用水浴和微波加热到内部终点温度分别为20、40、50、60、70、80℃和90℃,用示差扫描量热法研究肌束膜和肌内膜胶原蛋白热力特性(起始、最高和最终热收缩温度)在热处理过程中的变化。结果表明：牛半腱肌肉肌束膜和肌内膜胶原蛋白的热收缩温度在两种热处理方式间都存在显著差异,在两种热处理方式中,内部终点温度60℃是影响肌束膜和肌内膜胶原蛋白热收缩温度的关键加热温度。热诱导的肌束膜和肌内膜胶原蛋白热力特性的变化是水浴和微波加热牛肉胶原蛋白热收缩温度存在差异的主要原因。     

不同月龄肉羊肌内结缔组织中Ⅴ型胶原蛋白的特性

采用自然放牧条件下的6、9、12、18 月龄乌珠穆沁羊,取其半腱肌（Semitendinosus,ST）和背最长肌（Longissimus dorsi,LD）,提取并分离纯化肌内结缔组织中的Ⅴ型胶原蛋白。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、傅里叶变换红外光谱（Fourier transform infrared spectroscopy,FTIR）、热变性温度和氨基酸组成分析,比较各月龄段肉羊不同部位中Ⅴ型胶原蛋白的特性。结果表明：Ⅴ型胶原蛋白主要由α1(Ⅴ)、α2(Ⅴ)、α3(Ⅴ) 3 种亚基组成;ST和LD肌内结缔组织中Ⅴ型胶原蛋白的含量随着月龄的增长而增加,且各月龄间差异显著（P＜0.05）;在同一月龄段,ST肌内结缔组织中Ⅴ型胶原蛋白的含量高于LD;FTIR分析表明,各月龄段ST和LD肌内结缔组织中的Ⅴ型胶原蛋白均出现了主要吸收峰酰胺A、B及酰胺Ⅰ、Ⅱ、Ⅲ;ST肌内结缔组织中Ⅴ型胶原蛋白的热变性温度随着月龄的增长而显著升高（P＜0.05）,但9、12 月龄间无显著差异（P＞0.05）;LD肌内结缔组织中Ⅴ型胶原蛋白的热变性温度随着月龄的增长而升高,但9、12 月龄及12、18 月龄间无显著差异（P＞0.05）,其他月龄均差异显著（P＜0.05）;氨基酸组成分析结果表明,Ⅴ型胶原蛋白的总氨基酸、亚氨基酸及羟脯氨酸含量随着月龄的增长而呈上升趋势,且各月龄间有显著差异（P＜0.05）。本研究解释了随着肉羊月龄的增加,其骨骼肌肌内结缔组织中Ⅴ型胶原蛋白的特性变化。     

三种弱有机酸结合NaCl腌制对牛肉肌束膜和肌内膜胶原蛋白热力学特性影响

探讨三种弱有机酸(乳酸、醋酸和柠檬酸)结合NaCl腌制处理对牛肉肌束膜和肌内膜胶原蛋白热力学特性影响。牛半腱肌肉于4℃条件下分别经1.5%弱有机酸并与2%NaCl结合浸泡腌制24h,用差示扫描量热法研究肌束膜和肌内膜胶原蛋白热力特性(起始、最高和最终热收缩温度)在腌制处理过程中的变化。结果表明:3种弱有机酸的单独腌制处理后牛肉肌束膜胶原蛋白含量要比与NaCl的结合腌制处理低。不同腌制处理组之间,牛肉肌内膜胶原蛋白含量都有不同程度的差异。牛肉经腌制处理增强了肌内膜胶原蛋白的稳定性和部分处理组牛肉肌束膜胶原蛋白的热稳定性。     

低钠干腌肉加工过程中肌内结缔组织特性

以猪背最长肌为实验材料,食盐组为对照组,研究低钠盐对干腌肉加工过程中肌内结缔组织特性的影 响。结果显示：陈香结束后,低钠组次级肌束膜厚度比食盐组低0.72 μm（P＜0.05）,胶原蛋白热溶解性比食盐 组高0.91%（P＜0.05）,而低钠组胶原蛋白总含量、初级肌束膜厚度、成熟交联含量与食盐组相比差异不显著 （P＞0.05）。与食盐相比,低钠盐使α-螺旋、β-转角的相对含量分别减少了11.69%、13.41%（P＜0.05）,聚集 片、无规卷曲的相对含量分别增加了46.88%、5.82%（P＜0.05）。干腌猪肉加工中,低钠盐较食盐能进一步促进肌 内结缔组织蛋白降解。     

苏尼特羊骨骼肌总胶原蛋白含量的测定

本试验通过对不同月龄苏尼特羊的不同部位的肌肉总胶原蛋白含量的测定与分析,其结果表明,随着月龄的增加,总胶原蛋白的含量呈增加的趋势,相关分析表明,同一月龄不同部位肌肉中总胶原蛋白含量依次为:斜方肌>股二头肌>背最长肌>半腱肌,1、2月龄间总胶原蛋白含量在半腱肌和背最长肌之间没有显著性差异(P>0.05),其他月龄差异均显著(P<0.01),这些结果表明,通过测定肌肉总胶原蛋白的含量可以较客观的评价肉的嫩度。     

乌珠穆沁羊生长过程中肌内结缔组织中Ⅲ型胶原蛋白的变化

采用1至18月龄不同生长阶段乌珠穆沁羊为研究对象,对其骨骼肌内结缔组织中提取Ⅲ型胶原蛋白,并进行SDS-PAGE电泳鉴定,利用高效液相色谱测定所提取的Ⅲ型胶原蛋白中三种主要氨基酸含量,并依据羟脯氨酸含量计算出Ⅲ型胶原蛋白的含量,通过SAS软件分析肌内结缔组织中Ⅲ型胶原蛋白随月龄增加的变化规律。结果表明,随着乌珠穆沁羊月龄的增加,骨骼肌肌内结缔组织Ⅲ型胶原蛋白中甘氨酸和脯氨酸含量显著下降(P0.05),羟脯氨酸含量显著增加(P0.05)。Ⅲ型胶原蛋白的含量随着月龄的增加而显著增加(P0.05)。本研究对家畜生长过程中肌内结缔组织中胶原蛋白的性质、以及胶原蛋白对肉品质的影响起重要的作用。     

Structural weakening of intramuscular connective tissue during post mortem ageing of chicken Semitendinosus muscle

The structural changes in intramuscular connective tissues endomysium and perimysium during post mortem ageing in chicken semitendinosus muscle were investigated using an improved technique of scanning electron microscopy. In post mortem chicken aged for 12 h at 4°C, the endomysium resolved into individual collagen fibrils and the perimysial sheets separated into collagen fibres. These results provide direct evidence for the structural weakening of endomysium and perimysium during post mortem ageing. The structural changes in the intramuscular connective tissue were minimal until 6 h post mortem, but clearly observable after 12 h post mortem. It was concluded that this disintegration of the intramuscular connective tissue is the chief mechanism in tenderisation during extended post mortem ageing of chicken.     

Pyridinoline Cross-links in Bovine Muscle Collagen

Development of muscle collagen cross-linkage was investigated by determining hydroxylysylpyridinoline and lysylpyridinoline contents of longissimus dorsi, semitendinosus and extensor carpi ulnaris muscles. These were removed from male, female and castrated German Simmental cattle (150–620 days old) fattened on different energy levels and related to possible influences of sex, feeding intensity and type of muscle. In intramuscular collagen, an age-related increase in pyridinoline content was found. Cross-link formation was also influenced by sex and feeding intensity. Epimysia exhibited differences in pyridinoline content which were probably due to differences in physical strain of the muscles.     

Structural changes in endomysium and perimysium during post-mortem aging of chicken Semitendinosus muscle-Contribution of structural weakening of intramuscular connective tissue to meat tenderization

Post-mortem changes in endomysium and perimysium were investigated during aging of chicken semitendinosus muscle at 4°C. Although the shear-force value of raw meat decreased rapidly within 5 h post mortem and gradually thereafter, the solubility of collagen and the ratio of each chain of soluble collagen remained unchanged during 24 h post mortem. Light microscopic studies showed that structures of endomysium and perimysium disintegrated into several thin sheets within 12 h post mortem, and that many gaps opened in the cross-section of endomysium and perimysium. While endomysium and perimysium were not stained by periodic acid Schiff reagent in fresh muscle, they were markedly stained in muscle 12 h post mortem. These results provide direct evidence for the structural weakening of endomysium and perimysium during post-mortem aging of chicken. Therefore, we conclude that the structural weakening of the intramuscular connective tissue is closely related to tenderization of chicken.     

Three-dimensional observation of connective tissue of bovine masseter muscle under concentrate- and roughage-fed conditions by using immunohistochemical/confocal laser-scanning microscopic methods

ABSTRACT:  We investigated changes in connective tissue components of masseter (MA) muscle in Japanese black heifers ( n = 6) in concentrate- and roughage-fed groups (groups C and R, respectively). Body weight, at slaughter, of experimental heifers in group C (272.3 ± 22.3 kg) was higher ( P < 0.05) than that of group R (213.8 ± 27.5 kg). However, muscle weight and myofiber diameter (superficial and deep layers) of MA muscle did not differ between groups C and R. In contrast, total mastication duration of group R was longer ( P < 0.05) than that of group C. MA muscle of groups C and R was composed only of type I myofiber. Using immunohistochemical/confocal laser-scanning microscopy, type I collagen was observed mainly in perimysium, and type V and VI collagen were observed in perimysium and endomysium of both groups. Type IV collagen and laminin were observed only in the endomysium in both groups. However, type III collagen and fibronectin were strongly apparent in the perimysium and endomysium in group R. Connective tissue components in the perimysium of groups C and R were observed to form plate-shaped layers. On the other hand, honeycomb-shaped connective tissue components were seen in the endomysium-surrounded muscle fibers. In particular, fibronectin was strongly observed in the perimysium and endomysium in group R. These results indicate that there are different developmental changes among connective tissue components in MA muscle in response to mastication. The immunohistochemical/confocal laser-scanning microscopic method is useful to investigate the structural relationship among connective tissue components in skeletal muscle.     

饲养方式对宰后苏尼特羊肉一磷酸腺苷激活的蛋白激酶活力及糖酵解的影响

本研究测定了放牧和圈养条件下苏尼特羊宰后羊肉一磷酸腺苷激活的蛋白激酶（AMP-activated protein kinase,AMPK）活力、AMPK基因（PRKAA1、PRKAA2、PRKAG3）mRNA相对表达量和糖酵解指标,分析了 AMPK活力与糖酵解指标之间的相关性,研究不同饲养方式对羊肉AMPK活力及糖酵解的影响。结果表明：放牧条 件下苏尼特羊背最长肌的剪切力、亮度值以及黄度值均显著大于圈养条件（P＜0.05）;两种饲养方式的胴体初pH值 （pH1）和静止排酸24 h后胴体最终pH值（pH24）差异不显著（P＞0.05）;圈养条件下苏尼特羊PRKAA1和PRKAG3基 因的相对表达量显著大于放牧条件（P＜0.05）,PRKAA2基因相对表达量显著小于放牧条件（P＜0.05）;AMPK活 力和己糖激酶活力均为圈养条件大于放牧条件,但差异不显著（P＞0.05）;圈养条件下乳酸含量显著大于放牧条件 （P＜0.05）。通过相关性分析可知：PRKAG3基因相对表达量与AMPK活力、己糖激酶活力以及乳酸含量均呈显 著正相关（P＜0.05）,与剪切力呈显著负相关（P＜0.05）;PRKAA1基因相对表达量仅与乳酸含量呈显著正相关 （P＜0.05）;PRKAA2基因相对表达量与AMPK活力以及糖酵解指标无显著相关性;AMPK活力和己糖激酶活力以 及乳酸含量均呈显著正相关（P＜0.05）。综上所述,PRKAA1和PRKAG3基因相对表达量高时,AMPK被激活,使 己糖激酶活力增加,加速组织内的糖酵解,增加肌肉乳酸含量,降低pH值,进而影响肉的品质。     

Histological Contribution of Collagen Architecture to Beef Toughness

ABSTRACT:  The relationship between shear-force value and collagen architecture of connective tissue of the  longissimus thoracis  (LT) muscle of Japanese Black ( n  = 10) and Brown (Kumamoto) ( n  = 5) steers (body weight: 688.4 ± 8.6 kg as average and standard error) was investigated. There were negative correlations between the shear-force value and lipid content ( n  = 15,  R ²= 0.3709,  P  < 0.01) and protein content and lipid content ( n  = 15,  R ²= 0.6748,  P  < 0.01). Shear-force value and collagen content ( n  = 15,  R ²= 0.4344,  P  < 0.01) were positively correlated. In scanning electron microscopic photographs of the macerated preparation, the perimysium of the high-lipid LT muscle was broken down compared with the low-lipid LT muscle. The endomysium in all LT muscle fibers showed similar architecture. The fine surface cover of reticular collagen fibers around an adipocyte was observed in the high-lipid LT muscle perimysium. These results suggested that the shear-force value of the LT muscle was related to change in collagen architecture and of the perimysium in particular.