杂种野猪宰后肌肉品质特性的研究

品种是影响猪肉食用品质的最主要因素,而猪肉的化学组成成分和宰后生理生化变化则是肌肉品质形成的基础.本文针对杂种野猪和本地白猪两种不同的品种猪,在相同条件下饲养和屠宰,研究了宰后肌肉的色泽红度a值、pH值、嫩度(剪切力)和蒸煮损失的变化情况.试验表明:杂种野猪达到极限pH的时间比本地白猪的长,杂种野猪的嫩度比本地白猪差,但蒸煮损失率却比本地白猪肉低.     

不同种类淀粉对上浆猪肉片品质的影响

为研究不同种类淀粉对上浆猪肉片品质的影响,采用小麦淀粉、玉米淀粉和马铃薯淀粉对排酸成熟24 h的猪肉片进行上浆处理,未上浆猪肉片为空白对照,测定滑油后猪肉片的烹饪损失率、质构特性、色泽、水分含量、蛋白质含量、脂肪含量并观察其微观结构,同时利用模糊数学综合评价法分析其感官品质。结果表明,上浆猪肉片滑油后的烹饪损失率明显低于空白对照组,且马铃薯淀粉上浆猪肉片烹饪损失率最低,仅为4.83%。在质构特性和营养成分上,上浆猪肉片与未上浆猪肉片滑油后差异显著(P<0.05),马铃薯淀粉上浆猪肉片硬度值最小,弹性最大,水分含量最高,达67.91%。微观结构显示了马铃薯淀粉上浆猪肉片滑油后肌纤维结构更为松散,嫩度最好,与质构特性结果相符。模糊感官综合评分最高的是马铃薯淀粉上浆猪肉片,为81.45分。综合指标显示马铃薯淀粉更适于猪肉片上浆预制品加工。     

不同纯种猪肉食用品质分析

以进口纯种法系大白（FY）、法系长白（FL）、丹系大白（DY）和丹系长白（DL）猪肉为研究对象,对其食用品质进行系统分析,结合感官分析探究其色泽、口感和风味等特征的内在差异。结果表明：FY猪肉滴水损失率、剪切力显著较小（P<0.05）,红度值（a*）显著较高（P<0.05）,肌内脂肪含量较高;DL猪肉肌纤维直径最小、密度最大,其熟肉中5’-肌苷酸含量最高;感官分析结果显示,法系2个品种猪肉整体光泽度更好,肉香味更浓;FY猪肉的嫩度和多汁性更优;部分指标间的关联性符合猪肉品质特性。综上说明FY猪肉的肉色、嫩度、多汁性和风味等食用品质最优,其次为DL猪肉。     

藏猪肉冷藏期间的品质变化规律研究

研究以藏猪肉和普通猪肉的背最长肌为原料,对比研究藏猪肉与普通猪肉在冷藏过程中pH、水分含量、蒸煮损失率、TVB-N值等的变化规律。结果显示,新鲜藏猪肉具有较深的色泽;在4℃冷藏过程中,藏猪肉与普通猪肉各项指标的变化趋势相似,但藏猪肉的pH较高,而水分含量、蒸煮损失率和TVB-N值较低;整体上藏猪肉具有更高的感官接受度。研究为藏猪肉的保鲜和加工提供了重要参考。     

不同解冻方式对猪肉品质特性的影响

研究自然空气解冻、静水解冻、微波解冻和低温解冻4 种不同解冻方式对猪背最长肌肉品质特性的影响,分析猪肉解冻过程中食用品质特性、全质构特性、肌浆蛋白和全蛋白含量的变化。结果表明：冻结猪肉经静水解冻后,肌肉pH值接近6.0,解冻损失率和蒸煮损失率较低,静水解冻使猪肉的保水性维持较好。冻结猪肉解冻过程中肌浆蛋白和肌肉全蛋白浓度的变化对肉质构特性有显著或极显著影响。微波解冻有利于保持猪肉的嫩度和色泽,且通过微波解冻的冷冻猪肉其肌肉全蛋白含量较高,肉品的全质构特性较好。4 种解冻方法中,静水解冻和微波解冻能较好地保持解冻猪肉的品质。     

不同烹饪方式对骨膳食营养成分保留度的比较分析

为了分析不同烹饪方式对骨膳食营养成分保留度的影响,研究选取从某大型生鲜超市采购回来的带肉牛骨作为研究对象,分别选取油煎、低温烹饪和水煮三种不同的烹饪方式烹调牛肉,对比了不同烹饪方法烹调后牛肉质量损失率、蛋白质损失率、脂肪损失率、卵磷脂损失率、钙损失率情况以及感官品质评分,对比分析结果显示,低温烹煮后牛肉质量损失率最低,仅为32.74%;牛肉中的蛋白质损失率仅为9.78%;牛肉中的脂肪损失率相对较低,为47.82%左右;同时牛肉中卵磷脂成分保留度较高,钙损失率最低;同时,采用低温烹饪的方法加热牛肉无论在色泽,还是在味道和气味等感官品质评分均高于油煎和水煮,说明低温烹饪不仅能够有效提高骨膳食营养成分保留度,而且具有较高的感官品质评分。     

解冻、腌制方法对猪肉及香肠品质的影响

目的研究解冻方式、腌制条件对猪肉及香肠品质的影响。方法冷冻猪肉分别采用微波、流水、室温、低温解冻,采用4℃和10℃干腌法、湿腌法腌制,以解冻损失率、蒸煮损失率、剪切力、加压失水率、色泽评价猪肉及香肠品质。结果流水解冻与低温解冻解冻损失率较低,低温解冻蒸煮损失率最低,解冻的猪肉剪切力显著高于新鲜猪肉,常温解冻猪肉剪切力最低,而流水解冻猪肉加压失水率最低;干腌与湿腌对猪肉L*值影响不显著,干腌法腌制猪肉a*值、b*值高于湿腌法腌制猪肉,随着温度升高,干腌法腌制猪肉a*值降低,b*值增加,而湿腌法腌制猪肉a*值、b*值均降低;采用干腌法加工的香肠其水分含量、剪切力低于湿腌法,而蒸煮损失率高于湿腌法。结论流水解冻与低温解冻有利于保持猪肉品质,4℃干腌法加工香肠品质较高。     

不同浓度卡拉胶对猪肉品质影响的研究

试验研究了不同浓度卡拉胶对猪肉的感官品质、色泽、保水性、蒸煮损失率及嫩度等品质指标的影响。结果表明,添加不同浓度的卡拉胶后,对猪肉的感官品质有一定的影响,对猪肉的色泽有负面的影响,不同浓度影响效果不同,一般高浓度的对猪肉感官品质的负面影响较大。卡拉胶浓度与猪肉的感官评分、剪切力之间的回归方程均具有统计学上的显著意义,与猪肉的色差、保水性及蒸煮损失率之间的回归方程不具有统计学上的显著意义。     

不同解冻处理对猪肉理化特性及微生物数量的影响

以空气解冻、4 ℃冰箱解冻、静水解冻和微波解冻4 种不同解冻方式处理猪肉,分别测定处理后猪肉的汁 液流失率、蒸煮损失率、剪切力值、色泽、pH值、总挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量、 硫代巴比妥酸反应物（thiobarbituric acid reactive substance,TBARs）值、菌落总数及乳酸菌数量,研究解冻方式 对猪肉品质的影响。结果表明：静水解冻后猪肉的解冻汁液流失率（2.74%）、蒸煮损失率（16.60%）、亮度值 （57.12）、红度值（13.94）、TVB-N含量（12.95 mg/100 g）和TBARs值（0.10 mg/100 g）低于其他3 种解冻方 式,pH值接近鲜肉,菌落总数及乳酸菌数量较低,因此静水解冻对猪肉的理化性质具有较好的保持作用;4 ℃冰箱 解冻后猪肉的剪切力值（25.41 N）最低,对猪肉嫩度的保持效果较好;微波解冻猪肉的黄度值（11.06）最低;随 着肉样冻结时间的延长,解冻肉中的菌落总数与乳酸菌数量均呈波动变化趋势;肉中的微生物数量对其理化性质具 有显著或极显著影响。在4 种解冻方式中,静水解冻能更好地保持猪肉品质。     

基于模糊数学综合评价法确定燕麦麸猪肉丸中的淀粉种类

通过研究玉米淀粉、小麦淀粉、红薯淀粉和马铃薯淀粉对燕麦麸猪肉丸的物理指标(烹饪损失率、冻融析水率及总压出汁率)、感官性状、质构及色差的影响来确定最佳淀粉种类。以感官评定为基础对样品的滋味、弹性、表观状态和色泽进行权重分析,在此基础上利用模糊数学综合评价法对猪肉丸进行综合评分;利用质构仪测定硬度、弹性、黏聚性、咀嚼性和回复性,色差计测定色泽差异,并进一步进行感官品质、质构及色泽之间的相关性分析。实验表明:玉米淀粉使燕麦麸肉丸的烹饪损失率最小,且为负值,而马铃薯淀粉使样品的烹饪损失率最大,且为正值,但冻融析水率及总压出汁率无明显变化;模糊数学法评价燕麦麸肉丸品质的权重集为K=(滋味0.44,弹性0.21,表观状态0.18,色泽0.17),添加小麦淀粉的燕麦麸猪肉丸的感官评分最高,同时,仪器检测结果表明,添加小麦淀粉的燕麦麸猪肉丸的亮度最佳,色泽最好;相关性分析进一步表明,硬度与亮度是影响燕麦麸肉丸感官评价的主要质构及色泽因素。综上所述,小麦淀粉是燕麦麸猪肉丸中的最佳选择。     

PURIFICATION AND PROPERTIES OF PANTETHEINASE FROM PIG KIDNEY

Pantetheinase hydrolyzes specifically one of the carboamide linkages in pantetheine, leading to the formation of pantothenate and cysteamine. The enzyme from pig kidney cortex was purified to homogeneity as determined by SDS electrophoresis. Pantetheinase was solubilized by treatment with 1‐butanol, and then purified by thermal treatment, fractionation with ammonium sulfate and chromatography on CM‐Sephadex and DEAE‐Sephadex. The molecular weight of the purified pantetheinase was 72 kDa. No significant differences were found between the mercaptide and cysteamine methods for determination of the kinetic constants of the pantetheinase. The enzyme had a pH optimum of 9.0 and it was inhibited by pantethine and by oxidized glutation.     

GENETICS OF PIG MEAT QUALITY: A REVIEW

This paper is a review of current knowledge about genetic effects on technological and eating qualities of pork. These effects have been recognized as primordial sources of variation of meat quality in the porcine species. Nevertheless, some significant advances have recently been obtained in this area. This literature survey reveals that:
The halothane sensitivity gene (HALⁿ) explains to a large extent the overall genetic variation in technological quality and eating quality of pork. Evidence is accumulating that the halothane sensitivity gene is not completely recessive regarding its effects on quality traits. Producing slaughter pigs heterozygous at the HAL locus may result in deficiencies in meat quality, probably depending on slaughter conditions and perhaps also on slaughter weight.
Breed differences in technological and sensory qualities of pork partly result from the large breed variation in incidence of halothane sensitivity, but other factors are implied, particularly ultimate pH and intramuscular fat content of meat.
The major dominant gene RN^-is probably at the origin of the previously described "Hampshire effect" on meat quality.
Heritability of most traits referring to the technological quality of meat is low to moderate (0.15 to 0.30), whereas heritability of intramuscular fat content is high (0.40 to 0.50). A genetic antagonism exists between technological quality of pork and growth or body composition traits. The halothane sensitivity gene is the major factor responsible for the "meat quantity — meat quality" genetic antagonism.     

GLIADIN MODIFICATIONS CATALYZED BY GUINEA PIG LIVER TRANSGLUTAMINASE

Wheat gliadins, that are glutamine rich and lysine poor proteins, are good substrates for transglutaminases reactions. This study was conducted to determine the efficiency with which guinea pig liver transglutaminase catalyzes transfer and hydrolysis reactions of native and acylated gliadins. In all reactions, 35% of the total glutaminyl residues were modified. Neutral pH simultaneously enhanced glutaminyl residue hydrolysis and protein cross-linking, while acidic pH reduced the cross-linking reaction. Functional properties of two enzymatically modified gliadins and a chemically deamidated one were tested at neutral pH. A deamidation level of 25–27% appeared to be an optimum for the emulsification properties. Enzymatically modified gliadin showed better resistance to coalescence than the chemically deamidated one; a result that probably is related to the presence of high molecular weight polymers.     

Yeast PIG Genes: PIG1 Encodes a Putative Type 1 Phosphatase Subunit that Interacts with the Yeast Glycogen Synthase Gsy2p

The biosynthesis of glycogen involves multiple proteins that associate with each other and the glycogen macromolecule. In efforts to understand the nature of these proteins, a two-hybrid screen was undertaken to detect proteins able to interact with Gsy2p, a major form of glycogen synthase in Saccharomyces cerevisiae. Two positives expressed proteins derived from genes designated PIG1 and PIG2, on chromosomes XIIR and IXL respectively. PIG1 codes for a protein with 38% identity over a 230 residue segment to Gac1p, a protein thought to be a type 1 protein phosphatase targeting subunit whose loss impairs glycogen synthesis. Pig2p has 30% identity to the protein corresponding to an open reading frame, YER054, on chromosome V. Deletion of PIG1 on its own had little effect on glycogen storage but, in combination with loss of GAC1, caused a more severe glycogen-deficient phenotype than seen in gac1 mutants. This result is consistent with Pig1p being functionally related to Gac1p and we propose that Pig1p may be a type 1 phosphatase regulatory subunit. Delection of PIG2, YER054, or both genes together caused no detectable change in glycogen metabolism under the conditions tested. Gac1p, Pig1p, Pig2p and the YER054p are the only four proteins coded by the yeast genome that share a conserved segment of ∼25 residues, designated the GVNK motif, that is identifiable also in R_GI, the mammalian type 1 phosphatase targeting subunit. © 1997 by John Wiley & Sons, Ltd.     

PIG球管道清扫系统的设计与应用

介绍了PIG球管道清扫系统的组成、PIG球的选取、配套辅助设施的设计以及使用操作情况。     

MUSCLE CONTRACTION AND POSTMORTEM pH CHANGES IN PIG SKELETAL MUSCLE

SUMMARY– The initial (5 min) pH of longissimus dorsi muscle taken from live pigs under anesthesia was 7.0; in muscle taken immediately after slaughter it was 6.3. When the neuromuscular blocking agent, curare, was given intramuscularly before slaughter the initial pH was raised to 6.8. The gastrocnemius muscle was stimulated to contract via the sciatic nerve in vivo and the pattern of pH change compared with that of the unstimulated muscle in the other side of the animal. Stimulation caused a fall in initial pH and an acceleration in the subsequent rate of pH fall in the excised muscle under nitrogen at 37°. It was concluded that neural stimuli entering the muscle at the time of death were the major factors involved in the rapid postmortem glycolysis observed in the pigs studied.     

猪血中超氧化物歧化酶的分离工艺及稳定性研究

以新鲜猪血为原料,采用改进的提取工艺分离纯化超氧化物歧化酶(SOD),并通过SDS-PAGE等方法对酶样品能进行研究.实验结果显示,产品酶活性3022 U/mg,产率0.04%,SDS-PAGE电泳为单一蛋白酶带,分子量为31.2 ku,在pH 6.0～9.0具有良好的稳定性,在70℃以下具有良好的耐热稳定性.