| 1 | Characterisation of pH decline and meat color development of beef carcasses during the early postmortem period in a Chinese beef cattle abattoir显示文摘This study investigated the pH/temperature decline of beef carcasses in a typical Chinese abattoir and color development as pH declined during rigor onset. A natural cubic spline model was used to model the pH/temperature decline for those carcasses which passed through pH 6.0. Six of the 97 carcasses that exhibited a high(≥6.10) ultimate pH(pHu)(darkcutting) in the M. longissimus lumborum(LL) were sampled, along with the same numbers of normal pHu and intermediate pHu carcasses(5.40–5.79; 5.80–6.10, respectively), to examine color development within 24h postmortem. It was shown that 66.7% of the modeled carcasses were outside the ideal pH/temperature window with a temperature@pH6.0 lower than ideal, suggesting the need for acceleration of the pH decline. The stable and low a~*, b~* and chroma values of high pHu beef within the first 12h indicated dark-cutting beef might be detected earlier than expected. | ZHANG Yi-min David L.Hopkins ZHAO Xiao-xiao Remy van de Ven MAO Yan-wei ZHU Li-xian HAN Guang-xing LUO Xin | 2018 | Journal of Integrative Agriculture2018，17，7： | 4 |
| 2 | Implications of step-chilling on meat color investigated using proteome analysis of the sarcoplasmic protein fraction of beef longissimus lumborum muscle显示文摘In order to improve beef color and color stability,step-chilling(SC)was applied on excised bovine longissimus lumborum muscle,with chilling starting at 0–4℃ for 5 h,then holding the temperature at 12–18℃ for 6 h,followed by 0–4℃ again until 24 h post-mortem.pH and temperature were measured during rigor on SC loins as well as those subjected to routine chilling(RC,0–4℃,till 24 h post-mortem).Color L*,a*,b*values,metmyoglobin(MetM b)content,MetM b reducing ability(MRA)and NADH content were determined on samples aged for 1,7,and 14 d.Sarcoplasmic proteome analysis was only conducted on d 1 samples.The results showed muscles subjected to SC maintained a temperature at around 15℃ for 5 to 10 h post-mortem,and exhibited a slow temperature decline,but rapid pH decline.Beef steaks treated with SC had higher L*,a*,b* and chroma values than those of RC samples at 1 and 7 d chilled storage(0–4℃),while showing no significant difference for a*,b* and chroma values at d 14.The SC samples also exhibited a lower relative content of surface MetM b,higher MRA and NADH content,compared with RC beef steaks during storage,indicating the SC-treated beef showed an improved color stability.Eleven differential protein spots/nine proteins were identified by two-dimensional gel electrophoresis and mass spectrometry,and those proteins were mainly involved in redox,chaperone binding,metabolic and peroxidase activity.Oxidoreductases play a role in decreasing the oxidation-induced myoglobin oxidation and benefiting the production of NADH,and finally improving the colour of beef.Of these,pyruvate dehydrogenase E1 component subunit beta showed a positive correlation with color L*,a*,b*values and accounted for more than 60% of the variation in color values;this protein can be considered as a potential beef color biomarker.The present study provided valuable information for studies on the molecular mechanism of color improvement from step-chilling,as well as for identifying markers associated with beef color. | ZHANG Yi-min ZHANG Xiu-ze WANG Tian-tian David L.Hopkins MAO Yan-wei LIANG Rong-rong YANG Guang-fu LUO Xin ZHU Li-xian | 2018 | Journal of Integrative Agriculture2018，17，9： | 3 |
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