Modelling the decline of pH in muscles of lamb carcases

Assuming an exponential decay model (EDM) for pH decline as a function of temperature, ideal shortening (i.e. neither hot nor cold shortening) for an individual carcase occurs if and only if that carcase's model parameters fall within a specific sub-region of three dimensional space. This paper demonstrates that simply fitting EDMs to a sample of carcases and using the proportion of sampled carcases with estimated parameters within the specific sub-region can lead to seriously biassed estimates for the proportion of carcases ideally shortened. This is particularly so if the EDMs are fitted separately to each sampled carcase but also remains the case, to a lesser extent, if the models are fitted jointly using random effects modelling. A preferred estimate is based on the probability that an independently selected carcase has model parameters within the specific region, based on the distribution of the EMD parameters. The distribution of EMD parameters is obtained via the fitted random effects exponential decay model.     

The histology of blood splash in lamb

Ecchymosis (blood splash), can occur in the carcasses of animals that have been stunned electrically or shot with a captive bolt. While blood splash presents no health hazard, it is likely to detract from the acceptable appearance of the meat. Based on light and electron microscopic studies, ecchymosis has been shown to be due to the localised discharge of blood from ruptured blood vessels into the surrounding muscle tissue. A small proportion of muscle fibres in a splashed region were distorted ( 5 %) with irregular zones of high shortening interspersed with zones of lesser shortening. Such ‘supercontracture’ and its associated blood splash was markedly reduced by neuromuscular blocking agents. It is proposed that through supercontracture of some fibres, a severe strain is placed on adjacent blood vessels, occasionally leading to their rupture and hence to haemorrhaging.     

Application of NIR hyperspectral imaging for discrimination of lamb muscles

The potential of near-infrared (NIR) hyperspectral imaging system coupled with multivariate analysis was evaluated for discriminating three types of lamb muscles. Samples from semitendinosus (ST), Longissimus dorsi (LD) and Psoas Major (PM) of Charollais breed were imaged by a pushbroom hyperspectral imaging system with a spectral range of 900-1700 nm. Principal component analysis (PCA) was used for dimensionality reduction, wavelength selection and visualizing hyperspectral data. Six optimal wavelengths (934, 974, 1074, 1141, 1211 and 1308 nm) were selected from the eigenvector plot of PCA and then used for discrimination purpose. The results showed that it was possible to discriminate lamb muscles with overall accuracy of 100% using NIR hyperspectral reflectance spectra. An image processing algorithm was also developed for visualizing classification results in a pixel-wise scale with a high overall accuracy.     

Physical, chemical, and histological characteristics of 18 lamb muscles

Muscles (n = 18) were dissected from each side of 20 lamb carcasses to characterize physical, chemical, and histological traits. Muscles from the right sides were used to measure color values, expressible moisture, pH, total collagen content, and sarcomere length. Muscles from the left sides were aged for 7 d and used to determine Warner–Bratzler shear (WBS) force values. The M. adductor and M. semimembranosus had the darkest colored lean (lowest L^∗ values), whereas the M. latissimus dorsi and M. tensor fasciae latae had the lightest colored lean (highest L^∗ values). The M. triceps brachii, M. pectoralis profundus, and M. latissimus dorsi had among the lowest numerical expressible moistures whereas the M. adductor and the M. longissimus lumborum had among the highest. The M. infraspinatus was found to have the highest collagen content (9.0 mg/g) and the M. psoas major had the longest sarcomere length (3.1 μm). Of the muscles sampled, the M. serratus ventralis had one the lowest WBS values (21.8 N) and the M. semimembranosus the highest (42.6 N). On average, the largest muscles identified were the M. gluteobiceps, M. gluteus medius, M. longissimus lumborum, M. longissimus thoracis, and M. semimembranosus, which would likely be suitable in terms of physical dimensions for used in a variety of individual muscle applications. Other muscles, however, such as the M. teres major and M. tensor fasciae latae, may be too small in size and dimension to be used for individual application.     

Post-mortem evolution of non-protein nitrogen and its peptide composition in growing lamb muscles

Twenty-two 4-month-old lambs were used in two experiments to assess the effects of growth rate, induced by different feeding levels, and ageing (21 days, 4°C) on non-protein nitrogen (NPN) contents and their peptide composition. Muscle (Longissimus dorsi, Semimembranosus) and sex (male, female) effects were also studied. During ageing, NPN contents increased (15–20%). This variation represented 1.6–2.8% of total nitrogen. Peptides extracted from fresh muscles were in the range of molecular weight (MW) up to 12 kDa, the majority being less than 2.4 kDa (45–48%). During ageing, peptide average MW decreased (11.5–27.6%). High growth rate increased NPN contents at slaughter (+6–14%) and during ageing. Peptide average MW and post-mortem proteolysis rate as with to NPN variations were also higher. Differences between sex were observed at the end of the ageing period. Muscle effects were observed on the peptide class from 6.8 to 3.4 kDa.     

Effect of pre-slaughter injections of papain on toughness in lamb muscles induced by rapid chilling

The toughening of lamb meat induced by rapid chilling was found to be prevented in carcasses given a pre-slaughter injection of papain solution at the normal commercial dose level. Increased dose levels produced more tender meat.     

Proteome changes in lamb semimembranosus muscles associated with the inclusion of sunflower cake in their diet

A diet based on sunflower cake for lambs was assayed in order to reuse biodiesel industrial by-products with the aim of reducing livestock costs and evaluating their influence on meat quality. To achieve these goals, sixteen male lambs were fed diets containing different levels of sunflower cake (control, 5%, 10% and 15%). Afterwards, their semimembranosus muscles were analysed by two-dimensional electrophoresis coupled to mass spectrometry and their functional protein association was examined using STRING. Structural and metabolic proteins in the lambs’ proteomes changed significantly according to their diet. Fifteen proteins showed significant changes caused by the inclusion of sunflower cake, and the most differentially abundant structural proteins were detected in 2-DE gels from the lambs. Differentially abundant metabolic proteins such as ENO3 (enolase 3), MDH1 (malate dehydrogenase) and ALDH1A1 (retinal dehydrogenase) have been proposed as biomarkers of quality parameters in other species.     

Breed, slaughter weight and ageing time effects on consumer appraisal of three muscles of lamb

Consumers (n = 265) tasted semitendinosus (ST), semimembranosus (SM) and gluteo biceps (GB) (right and left) from 180 entire male lambs. Muscles were from three Spanish breeds: Rasa Aragonesa (local meat breed), Churra (local dairy breed) and Spanish Merino. Within breed, three slaughter live weights were considered (10–12, 20–22 or 30–32 kg). Isolated muscles were aged under vacuum package for 1, 2, 4, 8 or 16 days. Consumers evaluated tenderness, flavour quality and overall acceptability. Globally, the three attributes were significantly influenced by breed, slaughter live weight and ageing. Considering breed effect, Churra had the lowest scores for tenderness in the heaviest lambs while Spanish Merino was the most tender at 20–22 kg but there were no differences between either for 10–12 kg lambs. Muscles from the heaviest lambs were considered the toughest and those from the 10–12 kg lambs the most tender. Tenderness improved with ageing, but more for SM and GB. Flavour was better in the lightest lambs and, in general, it was not affected negatively by ageing. Consumers preferred meat from the 10–12 kg lambs in all breeds (the most tender and with the best flavour) and aged for intermediate to long periods (4–16 days). For the three attributes, the ST muscle had the best ratings at short ageing times and GB at long ageing times.     

Influence of feeding vitamin D(3) and aging on the tenderness of four lamb muscles

In Trial 1, rams (n=26) were fed different levels (0, 250,000, 500,000 or 750,000 IU) of vitamin D(3) for 4 days to determine the most effective dose to increase blood calcium concentrations. Trial 2 consisted of feeding feedlot lambs (n=40) different levels (0 or 750,000 IU) of vitamin D(3) for 14 days to determine if vitamin D(3) could improve the tenderness of lamb muscles. Lambs were slaughtered and the M. longissimus lumborum, M. biceps femoris, M. semitendinosus, and M. semimembranosus were removed after chilling, cut into chops, and assigned to an aging period (5, 10 or 15 days) for Warner-Bratzler shear force (WBS) determination. In Trial 1, feed intake and weight gain were lower for rams supplemented with 500,000 IU of vitamin D(3) compared to all other groups. Blood calcium concentrations were not different between groups, although the 750,000 IU group tended (P<0.10) to have higher blood calcium concentrations on day 5 of the trial compared to controls. In Trial 2, blood calcium concentrations were not different between the treated and control groups, however, treated lambs had higher (P<0.01) calcium concentrations in both the liver and kidneys. Control chops from the M. longissimus lumborum had lower (P<0.05) WBS values than chops from vitamin D(3) fed lambs, but no other muscles were affected by vitamin D(3) feeding. An interaction between treatment and aging was observed for the M. biceps femoris, with chops from vitamin D(3) fed lambs having lower WBS values at 5 days aging, but chops from control lambs having lower WBS values at 15 days aging. WBS values decreased for the M. longissimus lumborum, M. semitendinosus, and M. semimembranosus with increasing aging time. Vitamin D(3) supplementation was not an effective means of improving the tenderness characteristics of lamb muscles.     

Effect of postmortem time on the metmyoglobin reductase activity, oxygen consumption, and colour stability of different lamb muscles

The aim of this research was to characterize the lamb M. longissimus dorsi (LD), M. semitendinosus (ST), and M. psoas major (PM) muscles for differences in instrumental colour, tissue oxygen consumption rate (OCR), mitochondrial respiration control ratio (RCR), metmyoglobin reductase activity (MRA), and the relative proportions of myoglobin (Mb) redox forms. LD, ST, and PM muscles were stored for 6 days at 4 °C. Changes in the instrumental colour (CIE L*-value, a*-value, b*-value, Chroma-value, and Hue-value), OCR, RCR, MRA, and relative proportions of Mb redox forms during storage were evaluated. LD revealed the lowest MetMb accumulation and highest colour stability. Muscles with higher colour stability had lower levels of OCR, higher MRA, and less MetMb accumulation. Colour stability and MRA for the lamb muscles were LD > ST > PM. The correlation coefficients among the main parameters were also investigated in this research. The correlation coefficients between a*-value and OxyMb within the same muscle were highly significant (r = 0.951, 0.974, 0.828; P < 0.05). MRA of the muscles was negatively correlated (r = ?0.810, ?0.942, ?0.971, P < 0.05) with the relative percentage of MetMb. The results of the present study suggested that OCR, RCR and MRA contribute to variation in colour stability of different lamb muscles.     

Carcass posture and tenderness in frozen lamb

Toughness in lamb is determined by the extent of cold shortening occurring during chilling, and thaw shortening induced during cooking. Cold shortening sufficient to cause toughening is avoided by placing pre-rigor carcasses in a standing posture. Muscles are then largely restrained from shortening, though stimulated to do so by cold. Thaw shortening with its potential to toughen is eliminated as a problem merely by holding frozen lamb in storage (-12 ºC) for 20 days or more. These techniques for avoiding cold and thaw shortening can be compounded to form the basis of a simple processing method ensuring a uniform and high degree of tenderness, while still involving early freezing after slaughter. Carcasses are placed in a standing posture after dressing to prevent cold shortening during freezing. They are then held in frozen storage for a period to eliminate the possibility of thaw-rigor shortening on cooking.     

燕麦羊肉香肠的研制

燕麦羊肉香肠是以羊肉为主料,辅以燕麦的一种清真保健食品。通过对燕麦羊肉香肠配方的研究,并结合单因素和3因素正交试验以及感官评定最终得出结论:当燕麦粉、卡拉胶、孜然粉的添加量分别为10%、0.4%、0.5%时,做出的燕麦羊肉香肠色香味俱佳,实现了香肠营养强化和保健的目的。     

Spray chilling of lamb carcasses

Two spray-chilling treatments were developed to improve appearance and reduce weight loss during lamb chilling. Rates of cooling and weight loss and meat quality were compared to conventionally chilled carcasses.

The first treatment was an intermittent spray during the first 3 h of chilling. The second consisted of only two sprays at 2 h and 10 h post mortem. The conventional control was a two-stage process, with air at 10°C and 1 m/s up to 10 h post mortem, followed by air at 0°C and 1 m/s for a further 14 h.

Both treatments significantly reduced weight loss at 24 h post mortem compared to conventional, from 2·20% to 0·86% and 1·20%, respectively. During a further 4 days storage, the savings were maintained, with weight losses being 3·97%, 2·97% and 3·19%, respectively.

There were small (<1 h) but significantly reductions in the cooling times of spray-chilled loins and legs, attributed to sustained evaporative cooling of the continually wetted surfaces.

No effects on texture or drip loss and only slight effects on surface lean and fat colour were found. Variation in texture between animals within treatments was far greater than between treatments and could not be accounted for by variations in cooling rates.     

Comparison of glutathione peroxidase activity,and of total and soluble selenium content in two muscles from chicken,turkey, duck,ostrich and lamb

Glutathione peroxidase activity (GSHPx), total and soluble selenium in two muscles from five species were compared (chicken, duck, turkey, ostrich and lamb). The highest GSHPx activity, found in duck muscles (4.8 U/g; 3.0 U/g), was significantly higher than that in lamb (1.8 U/g; 1.4 U/g), turkey (1.2 U/g; 0.6 U/g), chicken (1.0 U/g; 0.7 U/g), and ostrich muscles (0.9 U/g; 0.8 U/g). GSHPx activities were significantly higher in the oxidative muscles from chicken (thigh), duck (breast), turkey (thigh) and lamb (PM) than those in the corresponding glycolytic muscles (breast, thigh, breast and LD, respectively). Also the total selenium content was higher in duck muscles (149 ng/g; 139 ng/g), than in lamb (171 ng/g /PM, M. psoas major/ and 86 ng/g /LD, M. longissimus dorsi/), chicken (117 ng/g; 109 ng/g), ostrich (106 ng/g; 103 ng/g) and turkey muscles (110 ng/g; 70 ng/g). The selenium content was significantly higher in the oxidative muscles of lamb and turkey than in the corresponding glycolytic muscles. The percentage of soluble selenium in lamb PM was lower (32%) than that in all other muscles (range 48–76%). The study thus showed considerable variation, among species, of glutathione peroxidase activity, total and soluble selenium content in muscle, which may be important for the oxidative stability and nutritional value of different meat products.     

The importance of transformations for traceability – A case study of lamb and lamb products

Vertical product information flow is important with regard to consumers’ perceptions of the meat which they buy. When research and analysis of traceability is carried out it is often found that critical points where information is systematically lost are encountered in the transformations of the resources. This study describes how lamb meat can be both tracked and traced through a lamb meat producer (company A). At company A 60% of the resource transformations were shown to be additions, mixing and splitting, these are considered to be those which produce the most critical traceability points. After an analysis of the current traceability system at company A suggested improvements were made. With regard to granularity of traceability they cannot trace individual animals during production, but rather a set of animals. The smallest traceable resource unit (TRU) company A can trace back to be a set of (identifiable) animals from one specific farm.     

Problems associated with commercial lamb washing in Ireland

Three methods for cleaning lamb carcasses were compared in an Irish export factory: (1) hot water (85-90°C) sprayed at high pressure (7 kg/cm(2)) (MRI), (2) a pneumatic gun using water at 40-50°C and 7 kg/cm(2) pressure and (3) soiled areas of the carcass were scrubbed with a nylon or bristle brush. Bacteriologically, the MRI method was marginally better than brushing but this had no effect on the ultimate shelf-life of the carcasses, which, in the prevailing conditions, was 8 days. All methods produced visually clean carcasses with good bloom. Both spray washing methods were considered impractical under commercial conditions, mainly because they were too slow.     

Effect of lamb age and retail packaging types on the quality of long-term chilled lamb loins

The objective of this study was to determine the impact of lamb age and packaging types on meat quality. Paired loins (M. longissimus dorsi) were obtained from 36 carcasses that included 4-month-old (New season; NS) and 11-month-old lambs (Old season; OS). The loins were vacuum-stored for eight weeks at − 1.5 °C. After storage, the loins were cut into subsamples and were randomly assigned to either high-oxygen modified atmosphere packaging (HiOx-MAP) or PVC-overwrapping for further display for 8 days. No differences between the age classes in shear force and drip loss were found (P > 0.05). OS loins had significantly higher myoglobin and redness compared with NS loins. HiOx-MAP initially induced a more intense red colour compared with PVC (P < 0.05), but resulted in severe discolouration at the end of display regardless of the age class. This observation suggests that the retail packaging type is the dominant factor over the age on lamb colour stability.