Variation of the sensory quality within the m. longissimus thoracis et lumborum of PSE and normal pork

This study evaluated the variation in instrumental and sensory meat quality within the m. longissimus thoracis et lumborum of carcasses with normal and PSE meat. Out of 80 slaughtered pigs, respectively, 9 and 7 carcasses were selected with a pH30 value > or=5.80 (normal pork) and a pH30 value <5.80 (PSE pork). Instrumental and sensory meat quality measurements were performed at three locations on these carcasses: longissimus thoracis (LT), longissimus thoracis et lumborum: (LTL-mid-loin) and longissimus lumborum (LL). Meat of the thoracis site (LT) was paler, but more favourable for pH45, cooking loss, juiciness, tenderness and preference scores than meat of the mid-loin part. The lumborum site (LL) was more or less in between the other two locations for meat quality, but closer to the LTL than the LT site. The meat quality variation within the m. longissimus thoracis et lumborum followed a similar pattern for normal and PSE carcasses. It can be concluded that the mid-loin part is best suited as a reference place for meat quality assessment, if one wants to eliminate carcasses with unacceptable meat.     

The relationship between animal age and the thermal stability and cross-link content of collagen from five goat muscles

The thermal stability of intramuscular collagen, as determined using differential scanning calorimetry, was measured in five muscles from 75 goats with known birth dates ranging in age from one day to 13 years. The collagen cross-link pyridinoline, and the collagen-associated, and putative cross-link, Ehrlich Chromogen were also measured. Five different muscles were examined and the effects of age compared to those found in the tendon of the longissimus dorsi muscle. The differences between intramuscular collagen and tendon collagen were found to be much greater than those between the intramuscular collagens of different muscles. Intramuscular collagen is more thermally stable than tendon collagen due to higher levels of heat-stable cross-links. However the increase in thermal stability of intramuscular collagen with age could not be explained simply in terms of the cross-links measured.     

Meat tenderness: Distribution of molecular species of collagen in bovine muscle

The collagen of bovine striated muscle has been shown to be comprised of three genetically distinct types of collagen, the proportions of which vary from the tendon to the endomysium. Despite the variation in genetic type all three collagens are stabilised by lysine-derived cross-links. It is proposed that the change in the tenderness of meat at temperatures above 65°C is caused by the tension generated during thermal contraction of all three types of collagen and that the extent is determined by the thermal stability of the intermolecular cross-links. The relative contributions of each type of collagen remain to be elucidated.     

Recommended terminology for the muscle commonly designated 'longissimus dorsi'

Musculus longissimus of the erector spinae is frequently used by meat scientists because of its relative mass, its commercial importance and its variability in quality. Its designation has fluctuated considerably due to confusion over interpretation of accepted anatomical guidelines, some of which have been altered to improve precision. We recommend that meat and muscle scientists refer to the part of the whole muscle they generally use as the Longissimus thoracis et lumborum (LTL) or to either of its two parts, Longissimus thoracis (LT) or longissimus lumborum (LL), depending on which is referenced. The word dorsi should be omitted, the word musculus (or its abbreviation M.) preceding all muscles in Latin should not be used in English, and the longissimus atlantis, capitis and cervicis should not be included except when they are actually used.     

Effect of cooking temperature and cooking time on Warner-Bratzler tenderness measurement and collagen content in rabbit meat

The effects of cooking temperature (50-90?°C) and time (10-120 min) on Warner-Bratzler (WB) tenderness measurement of longissimus lumborum (LL) muscle in 70-day-old rabbits were investigated. Cooking losses, total collagen content and collagen solubility of LL muscle were measured in parallel. Increasing cooking temperature caused a four-phase effect on WB measurement. Stress and total energy were significantly increased between raw meat and cooked meat at 50?°C, then they dramatically decreased to a minimum observed at 60-65?°C, and increased again to reach a maximum at 80-90?°C. Cooking losses exhibited an 83% increase between 50 and 80?°C. At 80?°C, stress and total energy values remained constant after 20 and 40 min respectively. LL muscle collagen content was 16.4±2.3 mg/g of dried muscle. Collagen solubility at 77?°C for 1 h was high: 75.3±8.1%.     

The rôle of epimysial, perimysial and endomysial collagen in determining texture in six bovine muscles

Epimysium, perimysium and endomysium were purified in high yield by a new extraction method from six bovine muscles of increasing toughness. In each case, the mean perimysial collagen fibre diameter, the total collagen content, the relative proportions of the major collagen types (I and III) and the collagen cross-link content were measured. Correlations were found between both collagen fibre diameter and collagen content of perimysial and endomysial connective tissue and meat toughness. No meaningful link could be made between textural quality of the meat and the relative content of types I and III collagen. Significant differences were seen, however, in both the total heat-stable cross-link content and the proportion of heat-stable collagen cross-links relative to heat-labile cross-links present in epimysium, perimysium and endomysiuim and the relative toughness of each muscle. The results are discussed with respect to the rôle of collagen in determining meat texture and toughness.     

延迟冷却对牛肉品质及超微结构影响的研究

本文研究了常规冷却与延迟冷却对中国杂交黄牛(鲁西黄牛×西门塔尔)宰后冷却过程中牛胴体pH值、温度变化、胴体冷却失重、肉色及成熟过程中剪切力值、背最长肌汁液损失、蒸煮损失、保水性、肌原纤维结构变化的影响.结果表明延迟冷却能减缓牛胴体温度的下降速率(P＜0.05),加快牛胴体pH值的降低(P＜0.05),提高牛背最长肌的嫩化速率,改善肉色(P＜0.05),但加剧了汁液损失、蒸煮损失,降低了保水性(P＜0.05).延迟冷却对成熟0d、3d时的肌原纤维结构影响显著(P＜0.05),延迟冷却组的肌节长度明显长于对照组的肌节长度.     

COLLAGEN CHARACTERISTICS AND MEAT TEXTURE OF PIGS EXPOSED TO DIFFERENT LEVELS OF PHYSICAL ACTIVITY

Intramuscular collagen and meat texture were measured in 23 female and 23 entire male pigs, subjected to one of three treatments: individual housing in pens of 2.5 m² (confined; C), individual housing and regular treadmill training (trained; T) and group housing equal to 0.9 m²/animal (free; F).
Treatment T tended (P = 0.13) to increase the activity of citrate synthase (CS) in M. biceps femoris (BF) from female pigs. Moreover, the heat stability of collagen and the mechanical resistance to 60 and 80% compression were increased (P<0.03) in BF from female pigs in treatments T and F as compared to C. In BF from male pigs, treatment T decreased (P = 0.03) the heat stability of collagen when compared to C and F. Sensory tenderness was not affected (P>0.05) by physical activity, however. In BF from female pigs, CS activity, collagen content and resistance to compression were lower (P<0.01) than in male pigs. In M. longissimus thoracis et lumborum, there was no effect of either physical activity or sex. Depending on muscle type and sex, physical activity affects meat texture.     

The effects of breed,sex, intramuscular fat and ultimate pH on pork tenderness

A study was conducted to evaluate the influence of breed and sex of animals on tenderness of pork. For evaluation, carcasses of pure breed barrows and gilts of Large White, Czech pig meat, Landrace and Duroc were used. For laboratory investigations, the samples of musculus longissimus lumborum et thoracis (20 mm thick) were taken from the same place, at the first cruciate vertebra 48 h post mortem. Seven days post mortem, the texture of heat-processed meat was measured objectively by the shear method on Instron equipped with Warner–Bratzler shear device. Meat tenderness and juiciness were also evaluated sensorially. It was observed that the tenderness of cooked meat is influenced by breed (the tenderest meat was from Duroc breed). The sex of animals has significant effect on meat tenderness too. At the same time, the effects of pH 45 minutes (pH₄₅) and 24 hours (pH₂₄) post mortem and intramuscular fat content on meat tenderness were evaluated. Correlations were found between shear force (tenderness) and intramuscular fat content and also between shear force and pH value 45 min post mortem. The shear force decreased with increasing intramuscular fat content and with increasing pH₄₅ value. Sensory evaluation of tenderness confirmed the objectively measured data.     

胶原蛋白对肉嫩度的影响

胶原蛋白是肌肉结缔组织的主要成分,胶原蛋白分子间交联的水平、方式和成熟程度对肌肉嫩度有很大的影响;胶原蛋白的含量、结构及性质对肉品质有显著的影响。本文着重对胶原蛋白分子在肌肉中的分布、胶原蛋白分子间交联及交联化学、胶原蛋白对肉品质的影响进行了综述和探讨。     

QUALITY CHARACTERISTICS OF MEAT FROM WILD RED DEER (CERVUS ELAPHUS L.) HINDS AND STAGS

The objective of the present study was to determine the chemical composition as well as physicochemical and sensory properties of meat ( musculus longissimus lumborum ) from red deer ( Cervus elaphus L.) hinds and stags harvested in forests of north-eastern Poland. Red deer meat was found to have a low fat content and a high content of total protein and water-soluble nitrogen in relation to total nitrogen. The total collagen content of meat was relatively low. Meat from hinds contained larger amounts of the above components (except for collagen). Meat from both hinds and stags had physical properties typical of venison, i.e., a dark color and a low pH level. Meat from hinds was characterized by better water-holding capacity. The relatively high TBARS value indicated lipid susceptibility to oxidation. The analyzed red deer meat had specific, but very good eating attributes (aroma, taste, juiciness, tenderness). Meat from stags was rated higher for taste and shear force.

PRACTICAL APPLICATION

Meat from animals raised under natural conditions has enjoyed a rise in popularity among consumers in recent years. The condition of "naturalness" is met by venison, which at the same time is known for its very high nutritive value and specific, but highly desirable, sensory properties. However, the nutritional and sensory qualities of venison should be analyzed in view of their great variation resulting from the impact of genetic and environmental factors, which remains insufficiently investigated, particularly with regard to wild populations.     

Measurement of nitric oxide and the effect of enhancing or inhibiting it on tenderness changes of meat

Possible roles of the cellular messenger nitric oxide (NO) in post-mortem meat ageing were investigated in bull m. longissimus lumborum. Both enhancement and inhibition of NO activity had positive and negative effects, respectively, on early rates of ageing. These also correlated with direct measurements of NO in the meat samples. However, by 8 days of storage, the tenderness was not significantly different to non treated meat samples.     

Growth, composition and eating quality of Longissimus dorsi from young bulls fed the β-agonist cimaterol at consecutive developmental stages

The objective was to investigate the effect of the β-adrenergic agonist, cimaterol, on gain, composition and meat quality of primerib (M. longissimus dorsi) from Friesian young bulls slaughtered at different developmental stages. Twelve pairs of monozygotic twins were allocated to three liveweight (LW) groups (162, 299 and 407 kg, respectively). Within each pair, one animal was given 0·056 mg cimaterol per kg LW for 90 days, while the other served as a control. Cimaterol treatment increased the estimated gain and the weight of primerib by 55 and 20%, respectively (both P < 0·001), and lean and protein content of the longissimus dorsi muscle by 26 and 25%, respectively (both P < 0·001), and concomitantly reduced fat content of primerib by 16% (P < 0·01) and intramuscular fat in longissimus dorsi by 36% (P < 0·001). Cimaterol treatment reduced total collagen content (P < 0·02), but not collagen solubility (P > 0·55). Meat colour was slightly lighter (lightness, P < 0·06), but pH(24) and pH(final) was not affected by cimaterol. Cimaterol increased Volodkevich shear force values (P < 0·001). In general, the effect of cimaterol on meat quality characteristics was evident in all three LW groups, and LW only affected percent fat in primerib, intramuscular fat content in longissimus dorsi, meat colour and absolute contents of protein, fat and bone.     

金川牦牛与麦洼牦牛舍饲育肥条件下肉品质的比较研究

本研究旨在比较在相同舍饲育肥条件下金川牦牛与麦洼牦牛肉品质的差异。选取年龄体重相近的金川牦牛与麦洼牦牛各24头,饲养100 d后各选取8头牦牛屠宰,采集背最长肌,分别进行TA-XT Plus质构仪在质地多面分析(texture profile analysis,TPA)模式下质构特性测定和肉品质测定。结果表明:金川牦牛肌肉滴水损失比麦洼牦牛低37%(p<0.05),生肉的剪切力比麦洼牦牛低49%(p<0.05)、弹性显著高于麦洼牦牛(p<0.05),煮熟金川牦牛肌肉的弹性显著低于麦洼牦牛(p<0.05),其他质构特性差异不显著(p>0.05)。金川牦牛背最长肌肌内脂肪含量显著高于麦洼牦牛(p<0.05),但背最长肌中脂肪酸的含量均无显著差异(p>0.05);麦洼牦牛背最长肌中缬氨酸、组氨酸以及脯氨酸的含量显著高于金川牦牛(p<0.05),其他氨基酸含量差异均不显著(p>0.05)。综上所述,与麦洼牦牛相比,金川牦牛肌肉的滴水损失、剪切力更低,而肌内脂肪含量更高,具有更好的肉制品开发潜力。     

Determination of endpoint temperatures in previously heat treated beef using reflectance spectroscopy

Heat processing endpoint temperature affects several quality parameters of meat. The present paper focuses on using near-infrared and visual light reflectance spectroscopy at 400-2500 nm to determine the endpoint temperature in previously heated ground beef. Glass fibre filters with beef juice centrifuged from m. longissimus lumborum were used as samples for the technique Dry Extract Spectroscopy by Infrared Reflection (DESIR). Combined with multivariate analysis, this method gave prediction errors down to ± 0.74 °C in the temperature range 65.6-75.6 °C, showing that DESIR is a potential screening method. The dominant part of the predictive information was in the visual part of the spectra.     

Oxidative stress may affect meat quality by interfering with collagen turnover by muscle fibroblasts

Oxidative stress in farm animals is an environmental/dietary factor that may contribute to the inconsistency in meat tenderness. This cell culture study investigated the ability of reactive oxygen species (ROS) to influence the turnover of intramuscular collagen, in terms of the balance between its degradation by the enzyme matrix metalloproteinase-2 (MMP-2) and its synthesis by intramuscular fibroblasts derived from 2 bovine muscles (longissimus dorsi, LD, and semitendinosus, ST). The potential for vitamins E and C to ameliorate the effects of oxidative stress on these fibroblasts was also studied.The response to oxidative stress treatments and combinations of vitamins C and E differed widely between cells derived from each muscle. Generally, ROS increase MMP2 activity and reduce collagen synthesis. Vitamins generally tend to counteract the effects of ROS on collagen synthesis. Oxidative stress may decrease synthesis of new collagen by intramuscular fibroblasts in some muscles, which could lead to decreased collagen solubility and hence increased meat toughness.     

Effect of castration on meat quality in Piemontese cattle

The effect of early (5 month) or late castration (13 month) on meat quality of hypertrophied Piemontese cattle was investigated. Twenty four animals, equally divided into three groups (early castrated, EC; late castrated, LC; intact males, IM) were reared under the same experimental conditions and slaughtered at the same age. Twenty four hours after slaughter the pH was measured on the longissimus thoracis of the right side. After 11 days of ageing the following analyses were performed on the longissimus thoracis et lumborum: water, protein and ether extract contents, hydroxyproline content and collagen solubility, colour (L, a(L), b(L), hue and chroma), drip and cooking losses, Warner-Bratzler shear values and sensory analysis (appearance of the raw meat and eating qualities of the cooked meat). Compared with intact males, the castrates had lower water and hydroxyproline contents and higher contents of protein and ether extract. No significant differences were observed between early and late castration, except for cooking losses.     

The association between acyl-CoA synthetase (ACSL4) polymorphism and intramuscular fat content in (Landrace × Yorkshire) × Duroc pigs

The aim of the study was to check whether different genotypes at acyl-CoA synthetase (ACSL4 locus, SNP G2645A) are associated with pork quality. 132 (Landrace × Yorkshire) × Duroc fatteners were genotyped by originally developed PCR-RFLP method. Upon the slaughter, the samples of longissimus lumborum muscle were taken from each carcass to determine the following parameters: content of water, protein and fat, pH (45 min, 24, 48, 96, and 144 h post mortem), electrical conductivity, drip loss, meat lightness, glycolytic potential, glycogen and lactate contents in meat. Among several associations observed, the highly significant (p<0.01) was found for intramuscular fat (IMF) content. Pigs with genotype GG revealed the highest content of IMF - 2.47%.     

Predicting temperature profiles to determine degree of doneness for beef biceps femoris and longissimus lumborum steaks

The degree of steak doneness is an important factor in providing consumers with a satisfying eating experience. Endpoint temperature and cooking rate are the determinants of degree of doneness. Our objectives were to predict internal temperature profiles and cooking times for longissimus lumborum and biceps femoris steaks. Each biceps femoris and longissimus lumborum steak was cooked individually in a gas-fired, forced-air-convection oven at 163 °C until the center temperature of each steak reached 70 °C. Temperature profiles were recorded by a Doric temperature recorder and the recorded time and temperature data were imported into a spreadsheet. A prediction method was then implemented to predict cooking times and temperature profiles. No significant differences (p<0.05) were found in cooking times between experimental and predicted values for either longissimus lumborum or biceps femoris steaks. Good agreement was found between experimental and predicted temperature profiles for the longissimus lumborum muscle. However, predicted temperature profiles were consistently higher (except for the beginning of the cooking cycle) than the experimental values up to 65 °C in the cooking cycle for biceps femoris steaks. A highly positive linear relationship was found between experimental and modeled temperature profiles for longissimus lumborum (R(2)=0.99), whereas a high quadratic (R(2)=0.99) relationship was found for biceps femoris steaks. Our method for predicting temperature profiles of steaks for a specified cooking time to attain a given degree of doneness should increase consumer satisfaction by reducing variation in meat sensory traits related to an expected degree of doneness.     

CHEMICAL COMPOSITION AND PHYSICOCHEMICAL PROPERTIES OF HORSE MEAT FROM THE LONGISSIMUS LUMBORUM AND SEMITENDINOSUS MUSCLE

The objective of this study was to compare the chemical composition and physicochemical quality of the meat of mature slaughter horses (73 mares and 58 geldings) sampled from the longissimus dorsi (longissimus lumborum section [LL]) and semitendinosus (ST) muscles.
The LL muscle was characterized by significantly lower values of electrical conductivity, temperature and shear force; however, it showed a significantly higher water-holding capacity. Meat from the LL muscle showed a significantly higher intramuscular fat (IMF) content, and as a result, higher calories, but contained less water and protein than the ST muscle. Along with the increasing marbling level, the IMF content in the LL muscle increased from 2.79 up to 13.30%, whereas in the ST muscle, from 2.80 up to 6.45%. Generally, a higher meat marbling goes together with a decrease of water and protein contents as well as an increase of a protein/fat ratio.

PRACTICAL APPLICATIONS

On the basis of the obtained results, it was stated that the chemical composition and physicochemical quality of mature horses' meat was similar to some other species of red meat. Therefore, the horse flesh could be a valuable substitute of culinary meat, especially beef. The high dressing percentages reflected the horses' usefulness for meat production. Moreover, considering a slight number of defects occurring in horse meat (i.e. DFD or PSE), chevaline could be more widely used in the meat industry, in raw or processed form, as a suitable food for human consumption.