牛肉电刺激仪的设计与试验

为了适合不同品种和部位的牛肉嫩化要求,该文研发了一种牛肉电刺激嫩化仪.该仪器以MSP430单片机和4个场效应管组成的H桥逆变电路为核心,以脉宽调制技术(PWM)为理论依据,通过控制单片机输出的PWM/SPWM(Sinusoidal PWM)方波占空比实现H桥对直流电逆变整形,从而产生不同波形.系统阐述了其功能原理、硬件...     

影响肉质嫩度calpain基因的研究进展

钙蛋白酶是一种存在于细胞内的非溶酶体性的限制性蛋白水解酶,在宰后肉质的嫩化和肉质的改善过程中起着重要的作用,本文对钙蛋白酶分类、结构、调节作用、嫩化机制及分离纯化方法等方面进行了阐述。     

离体条件下牛肉的嫩化机制

基于有关牛肉嫩化机制的钙激活酶、Ca 、溶酶体组织蛋白酶理论,本试验模拟尸僵后牛肉的内在环境和成熟温度,将纯化后的钙激活酶I、钙激活酶I内源性专一抑制剂、肌原纤维和钙激活酶I外源性抑制剂抑亮酶肽用于6个不同的处理组合,反应不同时间后,分别做变性聚丙烯酰胺凝胶电泳和蛋白质印迹分析。结果表明,在含100μmol/LCa 的反应体系中,钙激活酶I对肌间线蛋白和肌钙蛋白T有明显的降解作用,且降解产物和宰后牛肉自然成熟条件下的降解产物类似;钙激活酶I内源性专一抑制剂不能完全抑制钙激活酶Ⅰ的活性。100μmol/LCa 单独存在时对肌间线蛋白和肌钙蛋白T无降解作用,但很可能通过激活钙激活酶I间接发挥对肌原纤维的降解作用。     

冷却牦牛分割肉酶嫩化技术研究

牦牛肉色泽鲜红，风味纯正，营养丰富，但肌纤维较粗，易出现“冷收缩”现象，使质地坚硬，嫩度下降。为提高冷却牦牛肉的嫩度，改善肉质，该研究将木瓜蛋白酶用于冷却牦牛分割肉嫩化，通过L₉(3⁴)正交试验选择出最佳嫩化工艺参数，即酶浓度9 mg/kg，处理温度15℃，处理时间3 h。采用注射嫩化法，真空包装、急速冷却后在0～4℃条件下贮藏。结果表明，木瓜蛋白酶可明显提高肉的嫩度，使剪切力值(48.44 N/cm²、肌纤维直径(8.03 μm)、失水率(5.91%)下降，口感改善，对冷却肉的贮藏性无影响(0～4℃，9 d)，操作方法简单，成本低，适合工厂化生产，实用性强。     

Calpain activation and proteolysis in postmortem goose muscles

Meat tenderness is considered as the most important criterion for meat quality by consumers and can be improved by the actions of endogenous proteases, mainly calpains, during postmortem storage at 0–5°C. The purpose of this study, therefore, was to examine the postmortem calpain activation and proteolysis in breast (BM) and leg and thigh (LM) muscles of White Roman goose. BM and LM were taken from goose carcasses (n = 15) at 0 (10–15 min postmortem), 1, 3, and 7 days of storage at 5°C. The decrease in postmortem pH, calpain‐1 and ‐11 activities, and contents of the calpain‐1 80 kDa subunit and desmin was more rapid (p < .05) in BM than in LM. Our results show that postmortem proteolysis was more extensive in BM than in LM of White Roman goose, not only because the difference in fiber type composition between two muscles, but because the rate and extent of calpain activation were greater in BM as well. These results may provide useful information to optimize meat processing for different muscles in goose industry.     

Tenderization potential of Hanwoo beef muscles from carcasses with differed genders and loin intramuscular fat content levels during post mortem ageing

Carcasses from Hanwoo steers (n = 15) and cows (n = 15) were classified into three groups: group 1 (G1), the carcasses had 10% to < 11.5% intramuscular fat (IMF) in loin muscles; group 2 (G2), the carcasses had 13% to < 14.5% IMF in loin muscles; and group 3(G3), the carcasses had 17% to < 18.5% IMF in loin muscles. These were used to evaluate the effects of gender and carcass group on quality traits and Warner–Bratzler shear force (WBSF) of Psoas major (PM), Longissimus thoracis (LT), Longissimus lumborum (LL), Longus colli (LC), Supraspinatus (SS), Latissimus dorsi (LAD), Semimembranosus (SM), Quadriceps femoris (QF), Biceps femoris (BF) and Semitendinosus (ST) muscles. Our results showed that pH values of LT, LL, LC, BF and QF muscles were lower in steers than in cows (P < 0.05). Water holding capacity (WHC) was found higher in LC, SS, LAD and QF muscles of steers (P < 0.05). At day 2 of ageing, gender affected the WBSF values of only PM, LD and QF muscles in G1, and QF muscle in G3; however, with additional ageing, the gender effect was observed for most of the muscles. Most muscles showed ageing responses; however, the rates of ageing response significantly varied depending on gender and carcass groups. The muscles of G1 and G2 had generally higher tenderization potentials than those of G3. Furthermore, most muscles in G3 had generally lower WBSF values than in G1 and G2. These results clearly indicate that ageing has a significant effect on quality and WBSF of beef muscles, and the classification by loin IMF level may be useful for prediction of the tenderness of other muscles.     

原料肉的机械前处理工艺对猪肉切片火腿品质的影响

为了改善猪肉切片火腿出水、质构和口感问题,以精选猪后腿肉的股四头肌为主要原料,研究5种机械处理工艺对猪肉切片火腿系水性(蒸煮损失率、压榨失水率和杀菌失水率)、质构特性(硬度、弹性、内聚性和咀嚼度)、色泽和感官品质的影响。5种对原料肉的机械处理工艺包括只滚揉、注射腌制液后滚揉、嫩化后滚揉、注射后嫩化滚揉、腰刀绞制后滚揉。结果表明:注射和嫩化均可显著降低火腿的蒸煮损失率和压榨失水率,注射后嫩化滚揉的火腿的蒸煮损失率最低,为7.90%,而腰刀绞制后滚揉的火腿切片杀菌失水率最低,为2.66%,注射后嫩化滚揉与腰刀绞制后滚揉的火腿压榨失水率均最低,并且均显著低于其他处理组。注射和嫩化均可提高产品的硬度、内聚性和咀嚼度,注射嫩化滚揉组合处理与进行1种机械处理或2种机械处理相比,样品具有更好的质构特性,但是5种机械处理工艺中,腰刀绞制后滚揉的猪肉火腿硬度、内聚性和咀嚼度均最大。注射和嫩化有利于提高产品的亮度值(L*)和红度值(a*),降低产品的黄度值(b*)。通过感官评价可知,只经过滚揉的火腿具有最差的感官品质,注射后滚揉和嫩化后滚揉火腿的感官品质差异不大,注射后嫩化滚揉的火腿的质地和切片性低于腰刀绞制后滚揉的火腿,但是显肉性和色泽优于腰刀绞制后滚揉火腿。因此,工业化生产建议原料肉采用注射后嫩化滚揉处理,猪肉切片火腿具有最好的品质。     

乳酸对不同年龄秦川牛肉的嫩化效果

【目的】研究不同浓度乳酸对不同年龄秦川牛肉的嫩化效果,以筛选适宜的乳酸处理浓度。【方法】以剪切力为指标,研究不同浓度(0(CK),0.1,0.2,0.3,0.4和0.5 mol/L)乳酸按质量分数10%用量注射入肉样并于4℃放置1 d后,对不同年龄段(2.0,3.5和5.0岁)秦川牛肉的嫩化效果;通过石蜡切片观察,探讨乳酸对牛肉纤维结构的影响及其与牛肉嫩化效果的关系。【结果】随着乳酸浓度上升,不同年龄段秦川牛肉样的剪切力和pH值均逐渐下降,其中0.3 mol/L乳酸溶液对2.0岁秦川牛肉的嫩化效果较好(P<0.05),0.4 mol/L乳酸溶液对3.5和5.0岁秦川牛肉的嫩化效果较好(P<0.05);与对照相比,用乳酸处理后,牛肉肌纤维直径无显著(P>0.05)变化,肌纤维间隙显著(P<0.05)增大,剪切力显著(P<0.05)降低。【结论】乳酸能显著改善各年龄段秦川牛肉的嫩度,肌原纤维间隙也可作为衡量牛肉嫩化效果的指标。     

不同因素对秦川牛肉嫩化效果的影响

【目的】研究不同因素对秦川牛肉嫩化效果的影响,探讨肌纤维间隙与嫩化效果的关系。【方法】以秦川牛肉(背最长肌)为原料,用不同质量浓度(3,5,7,9和11 g/L)的氯化钙注射及不同质量浓度(0.03,0.05,0.07,0.09和0.11 g/L)木瓜蛋白酶和不同质量浓度(2,4,6,8和10 g/L)的焦磷酸钠、磷酸氢二钠、三聚磷酸钠进行浸渍,于4℃放置3 d,测定各处理肉样的剪切力,并对3种因素处理的最佳嫩化效果肉样作石蜡切片,测定肌纤维间隙。【结果】木瓜蛋白酶、氯化钙、焦磷酸钠均对牛肉有极显著的嫩化效果(P<0.01),其中以0.09 g/L的木瓜蛋白酶、3g/L的氯化钙和8 g/L的焦磷酸钠对牛肉的嫩化效果最为理想(P<0.01);与氯化钙和焦磷酸钠相比,木瓜蛋白酶的嫩化效果较好,且与其嫩化效果的差异达极显著水平(P<0.01),而氯化钙和焦磷酸钠对牛肉的嫩化效果无显著性差异(P>0.05),这与以肌纤维间隙作为嫩化指标时的测定结果一致。【结论】木瓜蛋白酶、氯化钙和磷酸盐均对牛肉有极显著的嫩化效果(P<0.01),但以木瓜蛋白酶的嫩化效果最佳;牛肉肌纤维间隙可以作为嫩化效果的评价指标。