This study aimed to examine changes in phosphorylation of sarcoplasmic and myofibrillar proteins from longissimus lumborum,semitendinosus,and psoas major muscles during postmortem ageing for 5 d.These sarcoplasmic and...This study aimed to examine changes in phosphorylation of sarcoplasmic and myofibrillar proteins from longissimus lumborum,semitendinosus,and psoas major muscles during postmortem ageing for 5 d.These sarcoplasmic and myofibrillar proteins were separated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and stained with phosphorous and protein specific stains.Myofibril fragmentation index,pH,the content of lactic acid and the relative activity of μ-calpain in three ovine muscles were measured.These results showed that the relative phosphorylation level of sarcoplasmic and myofibrillar proteins of psoas major muscle were lower compared with longissimus lumborum and semitendinosus muscles(P<0.05).The pH of psoas major muscle was the lowest at 0.5 h postmortem,and the highest after 12 h postmortem(P<0.05).In addition,the relative activity of μ-calpain was higher within 5 d postmortem and myofibril fragmentation index was higher after 1 d postmortem in psoas major muscle than those of longissimus lumborum and semitendinosus muscles(P<0.05).The sarcoplasmic protein phosphorylation may regulate the rate of pH decline to influence the μ-calpain activity and then proteolysis of proteins consequently.This study gives a new perspective of the mechanism of postmortem meat tenderization.展开更多
The effects of xanthan gum (0 % and 0.3 %) on the quality of low sodium (2.0 %, 2.4 %, 2.8 %, 3.2 %, 3.6 % and 4.0 %) salted beef and property of myofibril proteins (MP) extracted from salted beef were researched. Cha...The effects of xanthan gum (0 % and 0.3 %) on the quality of low sodium (2.0 %, 2.4 %, 2.8 %, 3.2 %, 3.6 % and 4.0 %) salted beef and property of myofibril proteins (MP) extracted from salted beef were researched. Changes in the salting absorptivity, cooking loss, shear force, color and sensory analysis showed that xanthan gum had a positive effect on the quality of salted beef with low salinity (2.0 %, 2.4 % and 2.8 %). MP of salted beef treated with xanthan gum had higher solubility, lower hydrogen bond than that without it (P < 0.05). The decrease of surface hydrophobicity and intrinsic fluorescence intensity indicated that the chromophore of protein was brought into a hydrophobic environment in the presence of xanthan gum. The electrophoresis showed that xanthan gum could improve the concentration of myosin heavy chain, paramyosin and actin after tumble-salting. The data suggested that salted beef and its MP treated with xanthan gum and 2.8 % salt (XS3) had the best properties. Together, xanthan gum could be considered as a sodium salt substitute for the development of low sodium meat products.展开更多
Purpose:The aim of this study was to extend current half-sarcomere models by involving a recently found force-mediated activation of the thick filament and analyze the effect of this mechanosensing regulation on the l...Purpose:The aim of this study was to extend current half-sarcomere models by involving a recently found force-mediated activation of the thick filament and analyze the effect of this mechanosensing regulation on the length stability of half-sarcomeres arranged in series.Methods:We included a super-relaxed state of myosin motors and its force-dependent activation in a conventional cross-bridge model.We simulated active stretches of a sarcomere consisting of 2 non-uniform half-sarcomeres on the descending limb of the force-length relationship.Results:The mechanosensing model predicts that,in a passive sarcomere on the descending limb of the force-length relationship,the longer half-sarcomere has a higher fraction of myosin motors in the on-state than the shorter half-sarcomere.The difference in the number of myosin motors in the on-state ensures that upon calcium-mediated thin filament activation,the force-dependent thick filament activation keeps differences in active force within 20%during an active stretch.In the classical cross-bridge model,the corresponding difference exceeds 80%,leading to great length instabilities.Conclusion:Our simulations suggest that,in contrast to the classical cross-bridge model,the mechanosensing regulation is able to stabilize a system of non-uniform half-sarcomeres arranged in series on the descending limb of the force-length relationship.展开更多
【目的】研究不同品种鸡胸肉肌原纤维特性与原料肉品质的关系,为筛选鸡肉加工专用品种、明确原料肉品质特性对鸡肉加工制品的影响提供理论依据。【方法】通过扫描电镜和透射电镜观察8个品种鸡胸肉的微观结构以及超微结构,利用Image-Pro ...【目的】研究不同品种鸡胸肉肌原纤维特性与原料肉品质的关系,为筛选鸡肉加工专用品种、明确原料肉品质特性对鸡肉加工制品的影响提供理论依据。【方法】通过扫描电镜和透射电镜观察8个品种鸡胸肉的微观结构以及超微结构,利用Image-Pro Plus 6.0软件定量分析肌原纤维直径、密度以及肌节长度;同时结合原料肉蒸煮损失率、剪切力、质构特性以及肌原纤维小片化指数(MFI)等品质指标,借助相关分析,建立肌原纤维特性与原料肉品质之间的相关性。试验数据采用SAS9.2软件进行方差分析、多重比较分析和相关性分析。【结果】通过比较8个品种鸡胸肉的基本化学组成成分,发现不同品种鸡胸肉化学组成成分之间存在显著差异(P<0.05),其中,乌鸡的水分含量为75.44%,显著高于(P<0.05)其它品种,而柴母鸡的水分含量最低;蛋白质含量变幅较小,为22.03%—24.53%,三黄鸡的蛋白质含量最高,贵妃鸡的蛋白质含量最低;贵妃鸡的肌内脂肪含量为3.11%,显著高于(P<0.05)其它品种。通过对8个品种鸡胸肉的基本品质指标分析,结果表明,不同品种鸡胸肉的色泽、pH、嫩度、持水能力及质构特性存在显著差异(P<0.05);矮脚鸡的亮度值和红度值显著高于(P<0.05)其它几个品种;乌鸡胸肉的pH最高;贵妃鸡、清远鸡、乌鸡及童子鸡胸肉的剪切力较其它几个品种鸡小;乌鸡胸肉的蒸煮损失率最低。8个品种鸡胸肉的微观结构和超微结构观察结果显示,不同品种鸡胸肉的肌原纤维直径、密度、肌节长度及肌原纤维小片化指数之间也存在显著差异(P<0.05),其中贵妃鸡、清远鸡、乌鸡及童子鸡的肌原纤维直径较细,密度较大;清远鸡的肌节长度最长;三黄鸡和贵妃鸡的MFI值较其它品种的大,分别为138.67和134.67。相关分析结果表明,肌原纤维直径与剪切力呈显著正相关(P<0.05),肌原纤维密度与剪切力呈显著负相关(P<0.05);肌节长度与蒸煮损失存在显著负相关关系(P<0.05)。【结论】肌原纤维特性与原料肉的品质存在密切的关联性,肌原纤维特性会对原料肉品质以及加工特性产生重要影响。展开更多
基金funded by the National Agricultural Science and Technology Innovation Program in China
文摘This study aimed to examine changes in phosphorylation of sarcoplasmic and myofibrillar proteins from longissimus lumborum,semitendinosus,and psoas major muscles during postmortem ageing for 5 d.These sarcoplasmic and myofibrillar proteins were separated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and stained with phosphorous and protein specific stains.Myofibril fragmentation index,pH,the content of lactic acid and the relative activity of μ-calpain in three ovine muscles were measured.These results showed that the relative phosphorylation level of sarcoplasmic and myofibrillar proteins of psoas major muscle were lower compared with longissimus lumborum and semitendinosus muscles(P<0.05).The pH of psoas major muscle was the lowest at 0.5 h postmortem,and the highest after 12 h postmortem(P<0.05).In addition,the relative activity of μ-calpain was higher within 5 d postmortem and myofibril fragmentation index was higher after 1 d postmortem in psoas major muscle than those of longissimus lumborum and semitendinosus muscles(P<0.05).The sarcoplasmic protein phosphorylation may regulate the rate of pH decline to influence the μ-calpain activity and then proteolysis of proteins consequently.This study gives a new perspective of the mechanism of postmortem meat tenderization.
基金the National Key Research Program of China(2016YFD0401501).
文摘The effects of xanthan gum (0 % and 0.3 %) on the quality of low sodium (2.0 %, 2.4 %, 2.8 %, 3.2 %, 3.6 % and 4.0 %) salted beef and property of myofibril proteins (MP) extracted from salted beef were researched. Changes in the salting absorptivity, cooking loss, shear force, color and sensory analysis showed that xanthan gum had a positive effect on the quality of salted beef with low salinity (2.0 %, 2.4 % and 2.8 %). MP of salted beef treated with xanthan gum had higher solubility, lower hydrogen bond than that without it (P < 0.05). The decrease of surface hydrophobicity and intrinsic fluorescence intensity indicated that the chromophore of protein was brought into a hydrophobic environment in the presence of xanthan gum. The electrophoresis showed that xanthan gum could improve the concentration of myosin heavy chain, paramyosin and actin after tumble-salting. The data suggested that salted beef and its MP treated with xanthan gum and 2.8 % salt (XS3) had the best properties. Together, xanthan gum could be considered as a sodium salt substitute for the development of low sodium meat products.
文摘Purpose:The aim of this study was to extend current half-sarcomere models by involving a recently found force-mediated activation of the thick filament and analyze the effect of this mechanosensing regulation on the length stability of half-sarcomeres arranged in series.Methods:We included a super-relaxed state of myosin motors and its force-dependent activation in a conventional cross-bridge model.We simulated active stretches of a sarcomere consisting of 2 non-uniform half-sarcomeres on the descending limb of the force-length relationship.Results:The mechanosensing model predicts that,in a passive sarcomere on the descending limb of the force-length relationship,the longer half-sarcomere has a higher fraction of myosin motors in the on-state than the shorter half-sarcomere.The difference in the number of myosin motors in the on-state ensures that upon calcium-mediated thin filament activation,the force-dependent thick filament activation keeps differences in active force within 20%during an active stretch.In the classical cross-bridge model,the corresponding difference exceeds 80%,leading to great length instabilities.Conclusion:Our simulations suggest that,in contrast to the classical cross-bridge model,the mechanosensing regulation is able to stabilize a system of non-uniform half-sarcomeres arranged in series on the descending limb of the force-length relationship.
文摘【目的】研究不同品种鸡胸肉肌原纤维特性与原料肉品质的关系,为筛选鸡肉加工专用品种、明确原料肉品质特性对鸡肉加工制品的影响提供理论依据。【方法】通过扫描电镜和透射电镜观察8个品种鸡胸肉的微观结构以及超微结构,利用Image-Pro Plus 6.0软件定量分析肌原纤维直径、密度以及肌节长度;同时结合原料肉蒸煮损失率、剪切力、质构特性以及肌原纤维小片化指数(MFI)等品质指标,借助相关分析,建立肌原纤维特性与原料肉品质之间的相关性。试验数据采用SAS9.2软件进行方差分析、多重比较分析和相关性分析。【结果】通过比较8个品种鸡胸肉的基本化学组成成分,发现不同品种鸡胸肉化学组成成分之间存在显著差异(P<0.05),其中,乌鸡的水分含量为75.44%,显著高于(P<0.05)其它品种,而柴母鸡的水分含量最低;蛋白质含量变幅较小,为22.03%—24.53%,三黄鸡的蛋白质含量最高,贵妃鸡的蛋白质含量最低;贵妃鸡的肌内脂肪含量为3.11%,显著高于(P<0.05)其它品种。通过对8个品种鸡胸肉的基本品质指标分析,结果表明,不同品种鸡胸肉的色泽、pH、嫩度、持水能力及质构特性存在显著差异(P<0.05);矮脚鸡的亮度值和红度值显著高于(P<0.05)其它几个品种;乌鸡胸肉的pH最高;贵妃鸡、清远鸡、乌鸡及童子鸡胸肉的剪切力较其它几个品种鸡小;乌鸡胸肉的蒸煮损失率最低。8个品种鸡胸肉的微观结构和超微结构观察结果显示,不同品种鸡胸肉的肌原纤维直径、密度、肌节长度及肌原纤维小片化指数之间也存在显著差异(P<0.05),其中贵妃鸡、清远鸡、乌鸡及童子鸡的肌原纤维直径较细,密度较大;清远鸡的肌节长度最长;三黄鸡和贵妃鸡的MFI值较其它品种的大,分别为138.67和134.67。相关分析结果表明,肌原纤维直径与剪切力呈显著正相关(P<0.05),肌原纤维密度与剪切力呈显著负相关(P<0.05);肌节长度与蒸煮损失存在显著负相关关系(P<0.05)。【结论】肌原纤维特性与原料肉的品质存在密切的关联性,肌原纤维特性会对原料肉品质以及加工特性产生重要影响。
