热处理对猪通脊嫩度及色泽的影响

肉类在热处理过程中的蒸煮损失、pH值、剪切力和色泽变化对肉的质地和感官具有重要影响。以猪通脊肉为原料,研究了不同的热处理温度和处理时间对猪通脊肉嫩度和色泽等物性的影响。结果表明:随着热处理温度的升高和处理时间的延长,猪通脊肉的蒸煮损失、pH值、红度a*和黄度b*均有显著的升高,亮度L*下降,而剪切力随着热处理时间的延长先升高后降低,且在整个过程中,温度越高,变化越迅速。     

热处理对牦牛肉品质的影响及其相关性分析

为研究热处理对牦牛肉品质的影响及各指标间的相关性,通过对牦牛背最长肌分别加热至中心温度50,60,70,80,90℃,测定不同热处理温度对牦牛肉肉色、剪切力、蒸煮损失、热收缩率以及感官品质的影响,并进行相关性分析。结果表明:随着温度的升高,牦牛肉的蒸煮损失、热收缩率、剪切力显著增大(P0.05);L*值和a*值显著下降(P0.05);中心温度为80℃时,牦牛肉的感官品质较好;相关性分析表明,除感官评价外,L*值、a*值、长度收缩率、宽度收缩率、高度收缩率、剪切力、蒸煮损失各指标均显著相关(P0.05)。总体来看,热处理使得牦牛肉的品质下降,但适宜的热处理有助于牦牛肉的感官品质提高。     

猪肉剪切力的测定方法

为建立可靠、规范的猪肉剪切力测定方法,研究不同加热中心温度(65～80℃)、水浴温度(70～80℃)、保温时间(0～20min)及冷却温度(0～25℃)对猪背最长肌剪切力值和蒸煮损失的影响。结果表明：猪肉的剪切力和蒸煮损失随着中心温度和水浴温度的升高、保温时间的延长而增加,冷却至0～4℃的肉样其剪切力值的变异系数最小,不同的预处理方法对猪肉剪切力的影响差异显著。综合而言,猪肉剪切力测定的预处理条件应为：水浴温度72℃,加热至中心温度70℃,不保温,煮后肉样放至0～4℃冷库中过夜。     

宰前碳酸水处理对猪肉品质的影响

试验通过对生猪宰前禁食期间饮用不同时间的碳酸水,研究碳酸水处理对宰后猪肉品质的影响。结果表明:通过宰前禁食期间碳酸水处理,对猪宰后不同时间测定的pH值都具有显著影响(P<0.05),且宰前饮用120min碳酸水时最终pH值有所偏高;禁食期间饮用碳酸水对宰后猪肉的色泽和持水力、剪切力值无显著影响(P>0.05),但对宰后猪肉的蒸煮损失均有显著影响(P<0.05),其试验组相比宰前饮用60min碳酸水时宰后猪肉的蒸煮损失最小,因此,宰前禁食期间饮用60min碳酸水时,猪肉品质最佳。     

大理石花纹、生理成熟度对牛肉品质的影响

依据我国农业行业标准《牛肉质量等级》,对不同大理石花纹和不同生理成熟度的牛肉品质进行试验分析,研究显示,大理石花纹对蒸煮损失有显著影响(p<0.05),对pH和剪切力值无显著影响,大理石花纹越丰富,蒸煮损失越小;生理成熟度对pH和蒸煮损失有显著影响(p<0.05),对剪切力值有较为显著影响(p<0.1),且随着生理成熟度的变老,即牛龄增加,牛肉的蒸煮损失和剪切力值呈增大趋势。     

性别对猪肉品质特性的影响

以去势公猪和母猪的背最长肌为材料,测定其理化指标,研究性别对猪肉品质特性的影响。结果表明：性别对猪肉的品质特性有明显影响。与母猪背最长肌的水分含量（75.16%）相比,去势公猪背最长肌的水分含量（74.40%）偏低;而去势公猪背最长肌的脂肪含量是母猪的2.5 倍左右;宰后pH24 值为5.85,相对母猪肉pH24 5.66较高;保水性较好;但其红度值为0.52,相对母猪肉红度值0.92较小;蒸煮损失为24.05%,相对母猪肉蒸煮损失21.76%较大;嫩度较差,去势公猪肉剪切力为5.10 kg,而母猪肉剪切力为3.79 kg。综合各项指标得出,去势公猪肉较宜于加工优质生鲜肉产品,但应注意改善产品的色泽和嫩度;而母猪肉由于在蒸煮损失和嫩度方面占优,较宜于加工灌肠等肉制品。     

宰后成熟时间与冷冻对猪肉品质的影响

为了探究宰后成熟时间和是否冷冻对猪肉食用品质的影响规律,采用均匀设计法设计实验,分别对宰后成熟过程中未冷冻肉样和冷冻肉样进行分析。结果表明:宰后成熟时间和是否冷冻对肉样的pH值、色差、蒸煮损失和剪切力影响显著(p0.05),两因素存在互作关系。随着宰后猪肉的成熟,两组肉样pH值、剪切力和蒸煮损失逐渐下降,且鲜肉样在成熟后期,剪切力下降趋于平缓;两组肉样a~*呈现先上升后下降的趋势,而b~*呈现先下降后上升的趋势,冻肉样L~*逐渐降低,鲜肉样L~*呈现先上升后下降的趋势。     

低压电刺激和冷却方式对猪肉品质特性的影响

采用2×2析因设计研究了低压电刺激和冷却方式对猪肉品质特性,包括背最长肌温度、pH、肉汁损失、煮制损失和剪切力的影响。结果表明,低压电刺激加快猪背最长肌pH下降,增大剪切力,对持水性有不利影响;二阶段冷却加快猪背最长肌温度下降,减缓pH的下降速率,显著降低肉汁损失,对剪切力没有显著影响。回归分析表明,煮制损失最能反映猪肉剪切力。采用二阶段冷却或低压电刺激配合二阶段冷却工艺可以保持良好的猪肉品质。     

不同注水量对猪肉食用品质的影响

通过研究不同注水量(0、10%、20%、30%、40%)对猪肉色泽、pH、剪切力、滴水损失、蒸煮损失、压榨损失、离心损失、贮藏损失、拿破率的影响,比较分析正常猪肉与不同比例注水猪肉食用品质的差异。结果表明:随着注水量的增加,L*、b*、滴水损失、蒸煮损失、压榨损失、离心损失、贮藏损失显著增大(p<0.05),a*、剪切力随着注水量的增加显著减小(p<0.05);当注水量小于20%时,注水猪肉的L*、压榨损失、贮藏损失、离心损失与正常猪肉差异显著(p<0.05),而当注水量大于等于20%时,注水猪肉的L*、a*、压榨损失、贮藏损失、离心损失、剪切力值、蒸煮损失、滴水损失均与正常猪肉存在显著性差异(p<0.05)。与正常猪肉相比,注水后的猪肉亮度增加,保水性变差,嫩度有所增加。相关性分析表明,注水后肉块保水性的变化影响色泽的改变,同时也会影响嫩度的变化。     

不同质量等级的中国黄牛肉在成熟过程中的品质变化研究

选取优一级、优二级和普通级中国黄牛牛胴体的外脊,测定其在成熟0、1、3、7、14、21和30h的剪切力值、pH、解冻滴水损失、蒸煮损失和熟肉率。结果表明,等级和成熟时间对外脊剪切力值有显著影响(p<0.05),等级对解冻滴水损失、蒸煮损失和熟肉率有极显著影响(p<0.01)。在同一成熟时间,级别越高,剪切力值越小,解冻滴水损失和蒸煮损失越小,熟肉率越高;随着成熟时间的延长,牛肉的剪切力值显著降低,解冻滴水损失和蒸煮损失显著增大(p<0.01)。     

The effects of aging on moisture-enhanced pork loins

The effects of preinjection aging time on pork loins injected with a salt/phosphate/lactate solution were investigated. Ninety-six fresh pork loins, in two replicates, were divided into two treatments. Loins in the first treatment were injected to 13% of loin weight at 1 day post-slaughter with a brine containing 2.17% salt/3.04% phosphate/20.8% lactate. The second group was injected with the same brine 4 days after slaughter. Color and Warner-Bratzler shear (WBS) force were measured immediately, 7 and 14 days after injection. Purge was measured 8 and 15 days postmortem. Western blots to measure troponin-T degradation were performed on samples from the two loins that resulted in the lowest shear force, and from the two loins that resulted in the highest shear force, as measured by Warner-Bratzler shear. The two loins with the most purge loss and the two loins with the least purge loss were also analyzed by Western blots for desmin degradation. The L(?) and b(?) color values were higher (P<0.05) and purge was greater (P<0.05) for loins injected 1 day postmortem than for loins injected 4 days postmortem. Western blots demonstrated that injection did not affect protein degradation. Therefore, differences between individual animals that affect protein degradation remain important regardless of injection treatment.     

The effects of irradiation on quality of injected fresh pork loins

A comparison of irradiation effects on injected and uninjected fresh pork loin quality was conducted. Sixty pork loins from pigs of similar genetics were obtained from a pork harvesting facility immediately prior to processing. Thirty loins were injected with a brine composed of 2.17% salt/3.04% phosphate/20.8% lactate brine while thirty were not injected. Injected loins were pumped to 13% added weight. Ten loins of each group of thirty were not irradiated while an additional 10 loins were irradiated at 2.2 kGy and the final ten loins were irradiated at 4.4 kGy. Lipid oxidation, color, purge, volatiles, and tenderness were measured on sections of the treated loins after 0, 7, 21, and 35 days of refrigerated storage. Lipid oxidation was minimal for the 0 and the 2.2 kGy-treated loins, but was significantly greater (P<0.05) at day 35 for the loins treated with 4.4 kGy. Warner-Bratzler shear (WBS) force measurements were significantly lower (P<0.05) for the injected loins, but irradiation did not have an effect on shear force. Purge was significantly lower for the uninjected loins irradiated at 2.2 kGy than for those irradiated at 0 and 4.4 kGy. The injection treatment did not alter the effects of irradiation on the quality characteristics measured.     

Association of single nucleotide polymorphism (SNP) markers in candidate genes and QTL regions with pork quality traits in commercial pigs

Numerous reports have described genetic markers or genomic regions (QTL) associated with pork quality and/or palatability but few validation studies have been reported. Therefore, 156 SNP markers from 45 candidate genes and eight QTL regions were analyzed for association with pork quality and palatability traits from 888 pork loins. Loins were collected at three slaughter facilities and selected to represent a wide range of pork color, pH and marbling. Phenotypic data recorded included objective and subjective measures of color and marbling, purge loss, shear force, and cooking loss. Data were analyzed with SAS PROC MIXED where loin was fit as a random effect. Results indicated some of the markers tested should be useful in industry, while others are not segregating in all populations or linkage disequilibrium between markers and causative genetic variation fluctuates among populations limiting their universal utility. Genes with the largest effects on pork quality were MC4R, IGF2, CAST and PRKAG3.     

Association of single nucleotide polymorphism (SNP) markers in candidate genes and QTL regions with pork quality traits in commercial pigs

Numerous reports have described genetic markers or genomic regions (QTL) associated with pork quality and/or palatability but few validation studies have been reported. Therefore, 156 SNP markers from 45 candidate genes and eight QTL regions were analyzed for association with pork quality and palatability traits from 888 pork loins. Loins were collected at three slaughter facilities and selected to represent a wide range of pork color, pH and marbling. Phenotypic data recorded included objective and subjective measures of color and marbling, purge loss, shear force, and cooking loss. Data were analyzed with SAS PROC MIXED where loin was fit as a random effect. Results indicated some of the markers tested should be useful in industry, while others are not segregating in all populations or linkage disequilibrium between markers and causative genetic variation fluctuates among populations limiting their universal utility. Genes with the largest effects on pork quality were MC4R, IGF2, CAST and PRKAG3.     

不同温度贮藏热鲜猪肉品质变化比较

比较研究25、20、15、10℃和4℃五种贮藏温度下的热鲜猪肉在食用品质(蒸煮损失率、剪切力、肉色)、pH值、挥发性盐基氮(TVB-N)和微生物上的差异。结果表明:25、20℃和15℃热鲜肉无最佳消费时段,10℃和4℃最佳消费时段分别在36h和48～72h左右;25、20、15、10℃和4℃的热鲜肉一级鲜消费时段分别在12、18、36、48h和96h内。在48h内,10℃贮藏的热鲜肉与4℃贮藏相比,在蒸煮损失率、肉色(L值和a值)和TVB-N值方面无显著差异,且剪切力变化优于4℃贮藏的热鲜肉。     

Differences in quality characteristics of normal, PSE and DFD pork

Differences in water-holding capacity, colour and tenderness/toughness were studied in 21 pork loins belonging to three quality categories, i.e. dark firm dry (DFD), normal and pale soft exudative (PSE). The division into the three groups was based upon the ultimate pH-values of the loins (< pH 5·5, pH 5·5-6·0, pH > 6·4). The PSE loins were characterized by a poor waterholding capacity, higher cooking loss and paler colour in contrast to the DFD category. The normal loins took an intermediate position. Neither sarcomere length, determined on fresh muscle tissue, nor Armour tenderometer values showed significant differences between the various quality categories. This was in contrast to the Warner-Bratzler (W-B) shear force values, determined on cooked loins, which had the lowest values in the DFD category. A strong relationship between the W-B values and the cooking losses was found. It was concluded that neither sarcomere length nor Armour tenderometer measurements were able to predict the shear force values of cooked pork loins.     

RAW MATERIAL pH, PUMP LEVEL AND PUMP COMPOSITION ON QUALITY CHARACTERISTICS OF PORK

ABTRACT
Boneless, paired pork loins (n=120) were selected based on pH at 14 h postmortem. Ultimate pH, drip loss, instrumental color (L*, a*, and b* values), and proximate analysis were determined prior to pumping. Paired loins were cut into four sections and pumped to 100%, 106%, 112% or 118% of original weight to result in a product containing 0.4% sodium tripolyphosphate (STP) for Experiment 1 (Exp. 1) and 0.4% STP plus 0.4% salt for Experiment 2 (Exp. 2). In Exp. I, additional pump level increased (P<0.05) vacuum package purge. Higher raw materials pH reduced purge. A pump level x pH interaction (P<0.05) occurred for cook loss at 70C. In Exp. 2, increased raw materials pH reduced (P<0.05) purge loss and resulted in juicier, more tender pork. Pumped pork had higher (P<0.05) tenderness, juiciness, and saltiness scores than controls.     

不同包装方式对猪背最长肌冷却成熟期间品质变化的影响

对猪背最长肌分别进行普通托盘和真空包装2种处理,研究了4℃成熟期间菌落总数、色泽、汁液流失、煮制损失、pH和乳酸含量的变化。结果表明:普通托盘包装的肉汁液流失低,L*较高,但微生物菌落总数增长较快;真空包装可有效抑制微生物菌落总数增长,但汁液流失较高、肉色L*较低。2种包装方式下猪背最长肌煮制损失没有显著差别,并且pH和乳酸在冷却成熟期间亦无显著变化。     

转谷氨酰胺酶改善PSE 猪肉西式香肠质构特性的研究

探讨转谷氨酰胺酶(transglutaminase,TG)及处理工艺对PSE 猪肉香肠质构特性的影响。测定在不同TG 质量分数、TG 处理时间、加热方式的条件下PSE 肉和正常肉(red,firm and non-exudative,RFN)肉糜蒸煮损失、凝胶强度和色度指标。结果表明：添加0.3% 的TG 可显著提高香肠的凝胶强度,但蒸煮损失也会增加;4℃条件下TG 处理的时间以2h 为宜;在20℃热水中升温加热比在75℃热水中直接加热所形成的凝胶强度大、蒸煮损失小;TG 质量分数和处理时间对凝胶色泽无显著影响,加热方式对凝胶的亮度(L*)和红度(a*)有显著影响。TG 处理可促进猪肉蛋白质的交联,改善PSE 猪肉西式香肠的质构品质。     

空气解冻温度对猪里脊肉品质的影响

以冷冻猪里脊肉为研究对象,在4、12、20、30 ℃温度条件下对其进行空气解冻,测定猪里脊肉解冻时 间、汁液流失率、蒸煮损失率、保水性、pH值、色泽、水分分布、质构和微观结构等特性变化。结果表明：猪里 脊肉汁液流失率与解冻时间呈非线性关系;12、20 ℃空气解冻对猪里脊肉的保水性影响较小;不同空气解冻温 度对猪里脊肉pH值、亮度值和红度值无显著影响;30 ℃空气解冻对猪里脊肉中不易流动水影响最小,稳定性 最好,其次为20、4、12 ℃;与对照组鲜肉相比,不同温度空气解冻处理组猪里脊肉蒸煮后硬度存在显著差异 （P＜0.05）;12 ℃空气解冻后猪里脊肉中肌纤维间空隙变大。不同空气解冻温度对猪里脊肉品质的影响存在 差异性。