USDA yield grades and various carcass traits as predictors of carcass composition

Twenty-five carcasses from each of three breedtypes (Brahman, Angus and Brahman × Angus) were physically separated into fat, lean and bone. Several muscles from the round and the femur were used to derive equations to predict carcass composition and muscle-to-bone ratio. The femur (as a percentage of the carcass) was shown to predict percentage carcass bone with 90% accuracy. All of the muscles studied were highly related to total carcass lean but the percentage of carcass as M. biceps femoris was the best single muscle indicator of carcass lean of the muscles studied. More variation in carcass lean could be accounted for by a multiple regression equation, involving all four muscles studied, than by any single muscle. M. biceps femoris-to-femur ratio was found to predict carcass muscle-to-bone ratio with a high degree of accuracy. The USDA yield grades were found to be reliable indicators of carcass composition. A two-variable equation involving adjusted fat thickness and biceps femoris accounted for 88·6% of the variation (RSD = 1/·64) in percentage of carcass as separable lean.     

陇西腊羊肉卤制过程中挥发性成分分析

目的 研究陇西腊羊肉在原料期、腌制期、卤煮期和高温灭菌期4个阶段挥发性风味物质的变化。方法 以陇西腊羊肉为研究对象,通过电子鼻和固相微萃取-气相色谱-质谱（SPME-GC-MS）联用技术,用相对气味活度值（ROAV）进行表征。结果 陇西腊羊肉在不同加工阶段中共检出74种挥发性风味物质,各阶段种类数分别为34、26、37、38种,峰面积占比先增大后减小。腌制期和卤煮期是影响腊羊肉风味的重要加工阶段。ROAV分析得出23种关键性风味物质,其中醛类对腊羊肉风味形成的贡献最大,烃类和醇类次之。1-辛烯-3-醇、己醛、壬醛为腊羊肉的特征性风味物质。总体来看,陇西腊羊肉加工过程中的挥发性风味物质在腌制期和卤煮期变化明显,且醛类、烃类、醇类是主要挥发物种类。结论 陇西腊羊肉在加工过程中的挥发性风味物质的变化,可促进陇西腊羊肉在现代化工业中关于风味控制技术的研发,加快其品质改良与工业进程。     

Effect of conditioning and carcass posture on eating quality of mutton from old Bannur ewes

Twenty-six mature ewes of an indigenous mutton breed, slaughtered and dressed conventionally, were used for the experiment described in this paper. The effect of three different conditioning temperatures and two methods of hanging posture on texture and palatability were assessed on leg muscles. Corresponding muscles from freshly slaughtered ewes were used as a control. A significant reduction was brought about in shear force in SM and BF muscles by different treatment combinations as compared with the control. There was, however, little variation in cohesiveness between treated and untreated BF and ST muscles. Holding carcasses at 14–15°C for 24 h, followed by chilling at 4–5°C for 24 h with pelvic hanging reduced shear values to the optimal level, as validated by sensory tenderness/toughness. The sensory parameters showed a significant difference between pelvic and Achilles tendon hanging. In all treatments pelvic hanging tenderised meat to a significantly greater extent than did Achilles tendon hanging.     

巴美肉羊及其杂交后代生长发育和胴体等级肉产量研究

选择4、6、8月龄巴美肉羊各10只,与同月龄的小尾寒羊、巴寒F1进行对比屠宰实验,分别测定并计算其体尺指标(体长、体高、胸围)、体尺指数(体型指数、胸围指数、体躯指数)和胴体等级分割肉质量,即一级肉(后腿肉和腰肉)、二级肉(肋肉和肩颈肉)、三级肉(腹下肉),确定巴美肉羊及其杂交后代在生长发育和胴体等级肉产量方面是否具有优越性.结果表明:巴美肉羊的胸围、胸围指数和体躯指数均显著大于同月龄小尾寒羊和巴寒F1(p＜0.05),且随着月龄增加,该类指标的增加速率也快于对照组肉羊.巴寒F1的胸围指数随着月龄增加发生了显著增加(p＜0.05),且巴美肉羊和巴寒F1的各等级肉质量均显著大于同月龄小尾寒羊(p＜0.05).同时,巴美肉羊和巴寒F1的各等级肉质量均显著大于同月龄小尾寒羊(p＜0.05),且随着月龄增加,其优质肉块的增长速率也大于其他肉块.因此,巴美肉羊与小尾寒羊和巴寒F1相比,具有良好的前躯和躯干相对发育能力以及该品种肉羊良好的优质肉块的产肉性能;而巴寒F1在其生长过程中与小尾寒羊相比也体现出了一定的杂交优势.     

PCR鉴定牛羊肉串搀杂猪肉的方法建立

建立了一种鉴定牛羊肉中掺杂猪肉的PCR检测方法.确定了一对可在牛羊肉中特异并灵敏地检测出所掺杂猪肉成分的引物对,以猪细胞色素b基因组为模板.特异性扩增出130bp的目的片段,而无其他扩增片段影响.在牛羊肉中分别掺杂2%、4%、6%的猪肉,均可灵敏地检测出猪肉成分,无显著性差异;分别经120℃、10min,120℃、30min,115℃、30min,70%、16h处理猪肉,也可灵敏地扩增出特定目的条带,无显著性差异.     

鸡肉代料制做油炸羊肉丸工艺

现在羊肉价格高,纯羊肉制做的肉丸成本较高,在此介绍一种以羊肉为主,以鸡肉为辅的羊肉丸制作工艺,加工后的肉丸在风味和口感上接近羊肉丸,且生产设备简单,适合中小型肉制品厂和家庭作坊加工.现将其加工工艺介绍如下.     

Decontamination of beef carcass tissue with nisin using a pilot scale model carcass washer

Nisin spray treatments were tested for controlling Gram-positive bacteria attached to beef carcass surface tissue using a pilot scale model carcass washer. Section of lean and adipose tissues were inoculated with approximately 4 log₁₀ cfu cm^-2 of Brochothrix thermosphacta, Carnobacterium divergens or Listeria innocua. Following 28°C water or nisin sprays, bacterial populations were enumerated immediately and after incubation for 24 h at 4°C. Spray treatments with water did not significantly alter the bacterial populations at day 0 or 1 (< 1 log₁₀ reduction). However, nisin spray treatments (5000 AU ml^-1) reduced populations by 1·79 to 3·54 log₁₀ cfu cm^-2 at day 0 and by 1·97 to 3·60 log₁₀ cfu cm^-2 at day 1. This study demonstrates that spray washing is an effective means of applying bacteriocins and that these compounds may be useful as sanitizers of red meat carcasses.     

羊肉的漂洗脱膻及风味羊肉丝的研制

采用漂洗法对羊肉进行脱膻处理,研究了温度、pH、肉水比及漂洗次数对脱膻效果的影响,利用单因素实验对漂洗条件进行了选择.同时研制了风味羊肉丝的加工工艺,利用正交实验对产品主要配料及主要工艺条件进行了优选.结果表明:利用温度40℃、pH8.2、肉∶水=1∶7的漂洗液对羊肉进行5次漂洗处理,脱膻效果良好;羊肉丝产品配方中添加酱油6%、食盐4%、白砂糖2.5%,在55℃下烘干2h,后于200℃烘烤2min,所得的羊肉丝风味品质良好.     

Prediction of lamb meat eating quality in two divergent breeds using various live animal and carcass measurements

This study investigated how accurately taste panel sensory assessments of meat eating quality (MEQ) could be predicted in two divergent lamb breeds, using predictors measured in live animals (weights, subjective conformation assessments, ultrasound, computed tomography (CT) and video image analysis measurements) and carcasses (weights, MLC fat and conformation classes, pH, temperature, carcass dimensions and cross-sectional tissue dimensions), individually and in optimal combinations. Grilled muscle samples from the pelvic limb (semimembranosus) and loin (Longissimus lumborum) of 120 Texel (TEX) and 112 Scottish Blackface (SBF) lambs were assessed by a trained taste panel for texture, juiciness, flavour, abnormal flavour and overall liking. Residual correlations (adjusted for fixed effects, age and sire) between MEQ and predictor traits were low to moderate in size (<±0.42). MEQ traits predicted best by single measurements were loin flavour and overall liking for TEX (using fat area in a CT scan or subcutaneous fat depth measured post-mortem), and for SBF were leg texture (using carcass weight or temperature) and juiciness (using CT fat area or shoulder conformation score). Combining live animal and carcass measurements increased MEQ prediction accuracies, compared with using either set alone, to explain >40% of residual variation in several MEQ traits, with the highest adjusted R² values for leg juiciness in TEX (0.53) and leg texture in SBF (0.59). The most useful predictors of MEQ depended on breed, with measurements of fatness generally more important in the lean breed and carcass size and muscling more important in the fatter breed.     

冷鲜羊肉品质的高光谱成像无损检测

利用400¹000 nm可见近红外高光谱成像系统对冷鲜羊肉蛋白质含量、嫩度、p H进行无损检测研究。采集冷鲜羊肉表面的高光谱散射图像,提取样本感兴趣区域的反射光谱曲线获得原始数据。先对原始光谱预处理并建立偏最小二乘回归（PLSR）模型,优选最佳预处理方法,后采用正自适应加权算法（CARS）和连续投影算法（SPA）提取特征波长,建立不同特征波长下各品质参数的PLSR预测模型。结果表明:利用原始光谱建立的冷鲜羊肉蛋白质、嫩度和p H的PLSR模型均优于经过光谱预处理所建PLSR模型;在不同波长下建立预测模型,OS-PLSR光谱模型对冷鲜羊肉蛋白质含量预测效果最佳,Rp=0.869,RMSEP=0.097;建立的SPA-PLSR光谱预测模型对p H预测效果理想,Rp=0.958,RMSEP=0.067;CARS-PLSR光谱预测模型对嫩度的预测能力较高,Rp=0.862,RMSEP=0.706。研究表明:利用可见近红外高光谱技术对冷鲜羊肉品质进行快速无损检测是可行的。      

Prediction of horse carcass composition using linear measurements

An analysis of meat quality performed on 107 horses showed that there are significant relationships between some linear measures of carcasses and the irrespective tissue contents. Thus, there is some potential for fat quantity estimation on the basis of nape fat thickness. The equation for the assessment of fat percentage in the carcass contains one variable, i.e., nape fat thickness only. However, even in this case the obtained multiple correlation coefficient was high, R=0.86 and the estimation error was at the level of 2.5%. As a consequence, the estimation of fat deposits in carcasses may be made more objective, and the measurement of nape fat thickness may be applied for the assessment of fat in the live animal.     

Estimation of heterogeneous within-herd variance components using empirical Bayes methods: a simulation study.

Genetic evaluation using BLUP can accommodate heterogeneous variances if the necessary variance components are known; this may require estimation of variance components within each heterogeneous subclass. Properties of sire and residual variance estimates obtained by an empirical Bayes approach, which combines within-herd and prior estimates, were examined via simulation. Prior estimates were obtained using REML across herds, as if variances were homogeneous. Convergence was improved by incorporation of prior information such that variance component estimates could be obtained in within-herd situations for which a REML algorithm failed to converge. Accuracy of sire variance estimates was greatest when both within-herd and prior information were used, but improvement in accuracy of residual variance estimates associated with incorporation of prior information was minimal. Correlations between sires' standardized true transmitting abilities and PTA that used empirical Bayes variance estimates were larger than those obtained when heterogeneity was ignored. Proportions of sires selected, based on standardized PTA, from environments with differing genetic and residual variances became more uniform as the relative weight placed on within-herd data in variance estimation increased. Thus, useful variance component estimates can be obtained within individual herds by using empirical Bayes methods with across-herd estimates as prior information; this may allow prediction of breeding values that are less influenced by heterogeneous variances.     

苏尼特羊肉氨基酸组成及与其他羊肉的对比分析

目的 分析苏尼特羊肉氨基酸组成以及与其他羊肉氨基酸组成进行对比分析。方法 以锡林郭勒放牧型苏尼特羊肉、乌珠穆沁羊肉、察哈尔羊肉以及两个区域舍饲型小尾寒羊肉为研究对象,通过氨基酸自动分析仪测定不同样品中氨基酸组成和含量,并进行比较分析。结果 苏尼特羊肉的水解氨基酸和游离氨基酸含量显著高于乌珠穆沁羊肉和察哈尔羊肉(P<0.05);苏尼特羊肉的水解氨基酸含量与舍饲型小尾寒羊肉无显著差异(P>0.05),但是其游离氨基酸含量显著高于舍饲型小尾寒羊肉。5种羊肉必需氨基酸/非必需氨基酸均高于60%,必需氨基酸/总氨基酸在40%左右,符合联合国粮农组织/世界卫生组织(UnitedNationsFood Agriculture Organization/World Health Organization, FAO/WHO)人体理想蛋白质模式。结论 苏尼特羊肉水解氨基酸和游离氨基酸组成丰富,含量较高,具有较高营养价值和食用品质。     

Dietary energy and protein effects on partitioning of carcass components in beef cattle

This study evaluated carcass and wholesale cut composition of 20 Angus steers fed two levels of protein (LP = 8% versus HP = 14%) at two levels of energy intake (LE = 1·96 versus HE = 2·67 Mcal ME) at 6·35 kg head⁻¹ d⁻¹ dry matter intake for 238 d using a factorial arrangement (n = 5/diet). The left side of each carcass was physically separated into wholesale cuts and each cut was, in turn, physically separated into the lean, subcutaneous fat, intermuscular fat, bone portions and cavity fat when applicable. Intramuscular fat for the entire side was chemically determined using only the separated lean tissue component. Energy was the greatest source of variation (P < 0·05) on carcass and wholesale cut composition: HE was associated with more total carcass fat (32·4 versus 23·9%) and less lean (56·7 versus 60·2%) and bone (17·9 versus 20·1%) than LE. Protein by energy level interactions (P < 0·05) were observed for carcass subcutaneous fat and carcass lean in addition to brisket subcutaneous fat, round subcutaneous fat and bone. The HP:HE group had the least carcass lean and the most subcutaneous fat followed by the LP:HE group, LP:LE and then HP:LE. This was also the trend for the wholesale cut composition. These results suggest that fat deposition in cattle can be significantly and favorably reduced in wholesale cuts by adjusting the relative balance of dietary protein and energy.     

酶法水解羊肉制备肉味香精的研究

研究Flavourzyme复合风味蛋白酶和Protamex复合蛋白酶对羊肉的酶促水解,以及水解液通过Maillard反应合成肉味香精.研究表明:Flavourzyme和Protamex的最佳配比为1:1,最佳水解条件为45℃,pH 7.0,底物浓度30%,组合酶浓度0.8%(E/S);以组合酶最佳水解条件下所得羊肉水解液作为Maillard反应基料,采用羊肉酶解液50g植物水解蛋白fHVP)8.0g葡萄糖2.0g木糖1.0g、丙氨酸0.6 g、I+G0.8 g、羊脂4.0 g、L-半胱氨酸盐酸盐0.5 g、酵母膏5.0 g、VB 10.5 g,在110℃反应30 rain,得到具有酱羊肉风味的香精.     

Cooling-induced contraction of mutton

The authors studied the effects of various cooling temperatures on the tenderness of mutton. It was found that a marked increase in toughness is produced in particular by temperatures less than 10 degrees C. Measurements of the length of myomere and muscle fibres indicate the relationship between toughness and muscular contraction, contractions of more than 15-20% leading to marked losses in tenderness.     

Estimating beef carcass composition using the speed of ultrasound

The reciprocal of the speed of 2·25 MHz (nominal) ultrasound (RV) was measured at selected sites through the soft tissues of 72 beef carcasses from Friesian. Hereford and Hereford × Friesian bulls and steers at or within 1 h of stunning. The measurement sites were: through M. adductor horizontal to the caudal edge of the symphysis pubis (S2), through M. scalenus just cranial to the first rib (S3) and through M. longissimus thoracis between the tenth and eleventh ribs, approximately 6 cm from the midline (S4). The thickness of extractable lipid (d(f)) at each site was defined as the product βd, where β was the volume fraction of extractable lipid and d was the tissue thickness. The thickness of lipid-free tissue (d(ff)) was defined as (d-d(f)) and β was calculated from the ultrasonic measurements using an empirical linear relation between β and RV. When cold, the intact sides were scored independently for fatness and conformation by two experienced judges according to the EAAP system and their mean scores determined. Sides were split at the level of the last rib and the depth of subcutaneous fat measured at 25%, 50% and 75% of the width of M. longissimus thoracis from the midline. The three ultrasonic characteristics (RV, d(f) and d(ff)) at each site, the mean fat depth and the mean fat and conformation scores were examined for correlation with % fat and % lean in the sides determined by complete physical dissection. The best predictors of % fat were mean d(f) at S3 and S4, mean d(f) at S2, S3 and S4 and mean EAAP fat score which were all of comparable precision (rsd, respectively, 2·07, 2·06 and 2·08). The best predictors of % muscle were mean d(f) at S3 and S4, mean d(f) at S2, S3 and S4 and mean RV at S2, S3 and S4 (rsd, respectively, 1·79, 1·79 and 1·90). The corresponding residual standard deviations for mean EAAP fat score and mean fat depth were 2·18 and 2·20.     

电刺激和吊挂对羊肉贮藏期肉质嫩化效果的影响

采用电刺激、吊挂两种方式处理屠宰后不久的羊肉,再放入0～4℃冷藏16d。测定羊肉在储藏期间剪切力、pH、蒸煮损失率、挥发性盐基氮(TVBN)、肌原纤维小片化指数(MFI)以及蛋白质电泳等指标的动态变化。实验结果表明:电刺激可以降低羊肉的剪切力,加快羊肉pH的下降,提高肌原纤维小片化指数,加快蛋白质的降解,对持水性有不利影响;吊挂可以降低羊肉的剪切力,减缓pH下降速率,对持水性无显著影响。由此得出,电刺激和吊挂处理均能提高羊肉嫩度,但与吊挂相比,电刺激能缩短羊肉的成熟时间(2～3d),显著的改善了羊肉的品质。      

电刺激和吊挂对羊肉贮藏期肉质嫩化效果的影响

采用电刺激、吊挂两种方式处理屠宰后不久的羊肉,再放入0～4℃冷藏16d测定羊肉在储藏期间剪切力、pH、蒸煮损失率、挥发性盐基氮(TVBN)、肌原纤维小片化指数(MFI)以及蛋白质电泳等指标的动态变化 . 实验结果表明:电刺激可以降低羊肉的剪切力,加快羊肉pH的下降,提高肌原纤维小片化指数,加快蛋白质的降解,对持水性有不利影响:吊挂可以降低羊肉的剪切力,减缓pH下降速率,对持水性无显著影响 . 由此得出,电刺激和吊挂处理均能提高羊肉嫩度,但与吊挂相比,电刺激能缩短羊肉的成熟时间(2～3d),显著的改善了羊肉的品质.     

Growth of carcass components and its relation with conformation in pigs of three types

The growth of carcass tissues and developmental changes in tissue distribution were studied in three pig types which were selected to have morphologies that could be described as attenuated, blocky and flabby. These were achieved by incorporating, respectively, Landrace, Pietrain and Meishan genes to give commercial 'types' (designated L, P and M,) exhibiting some of the phenotypic qualities of these breeds. Twenty-five female pigs of each type with an average start weight of 27.2 kg were fed ad libitum and slaughtered over a (nominal) live weight range of 35-115 kg. Relations were quantified using the logarithmic transformation of data in the allometric model. Significant type differences in relative growth rates (the b coefficient or slope in the logarithmic plot) were not common, occurring in 14% of the relationships examined, whereas 61% of differences in the constant term (a or intercept in the logarithmic plot) were significant. Increase in carcass weight with age was not different between the types but in relation to slaughter live weight (dressing percentage) P had the highest value, M the lowest. Carcass dimensions showed that, relative to body length, P had the widest ham and shoulder over the whole size range whereas M had a deep (ventral-dorsal) shoulder and wide belly, attributes of shape that would be regarded as undesirable by the meat trade. Relative to carcass weight, L was only slightly longer (3 mm) in the body than M at the heavy end of the weight range but markedly longer (29 mm) than P. These differences in carcass conformation were also evident in the shape of pelvic limb muscles which, at a given length, were lightest and narrowest in M and, in some cases, heavier and wider in P than in L. Pelvic limb volume relative to limb length was greatest in P and least in M. Carcass composition (at a given prepared side weight) of P was characterized by low fat and high lean weights, and a high lean to bone ratio. Subcutaneous fat b was lowest in P, indicating that P was early maturing, but M carcasses had the most subcutaneous and intermuscular fat, also indicative of early maturing. There was, thus, no simple relation between maturity characteristics and carcass composition. M carcasses also had the greatest weight of skin. P had a light hindloin and heavy pelvic limb, M a heavy shoulder, hindloin and flank but a light pelvic limb; L had a light shoulder but a heavy foreloin. The distribution of individual tissues mirrored these differences in joint weights to a varying extent; in most cases the match (relatively heavy/light) was with a single tissue. These data, thus, indicated some pig type differences in tissue distribution and of particular significance was the relatively light lean mass in the pelvic limb of M. The results showed important differences in carcass quality between commercially available pig types differing in conformation.