ABSTRACT
Six types of dry‐cured hams were chemically profiled for proximate composition and low molecular weight nonprotein nitrogen (NPN) fractions including free amino acids (FAA) and two ...dipeptides (carnosine and anserine). Results indicate that FAA were present in the six classes at different (mg/100g protein) concentrations, with Iberian and Serrano containing greater (P<0.05) amounts of most FAA. However, when analyzed as percentage (mg/100g total FAAs) values, FAA contents of Iberian and Serrano hams exhibited lower (P<0.05) tyrosine and greater (P<0.05) aspartic acid and threonine values. Within each class, large variation coefficients (>10%) for nonprotein nitrogen paralleled inconsistent values of salt content, to which NPN and FAAs were negatively correlated (P<0.01). NPN was also negatively affected by moisture in the dried muscle, indicating limited saltiness and greater muscle shrinkage as two major determinants in developing of nonprotein fractions, hence of free amino acids.
An experiment involving 32 individually housed, castrated male pigs was conducted to determine the effects of environmental temperature (12 degrees C = T12 or 28 degrees C = T28) on the performance, ...carcass characteristics, muscle and adipose tissue metabolism, and meat quality of pigs fed to achieve equal rates of weight gain between 8 and 92 kg live weight. The T12 pigs had less muscle (P 0.01) and more subcutaneous fat (P 0.01) in the ham than did T28 animals. Thyroids and adrenals were heavier (P 0.01) in T12 than in T28 pigs. Percentage of type I muscle fibers was higher (P 0.01) and fiber cross-sectional areas smaller (P 0.01) in semispinalis muscle (SS) of T12 pigs, whereas no effect of temperature was noticed in longissimus muscle (LD). Cold exposure induced a larger increase in oxidative metabolism in SS (+30 to 32%, P 0.001) than in LD (+14 to 17%, P 0.10) and an enhanced glycolytic metabolism in LD (P 0.05). Lipid concentration was higher in SS of T12 than in that of T28 pigs. Lipogenic enzyme activities and unsaturation of backfat were higher in T12 than in T28 pigs, whereas no effect of temperature was noticed in leaf fat. Cold treatment resulted in a faster postmortem pH decline (P 0.01), higher glycolytic potential (P 0.01), and lower ultimate pH (P 0.01) in LD. The results indicate that 12 degrees C vs 28 degrees C induced detrimental effects on growth, ham composition, and muscle and adipose tissue quality
The halothane sensitivity allele (n) is known to be detrimental to meat quality, causing meat to become increasingly prone to being pale, soft, and exudative (PSE), while exerting a favourable ...influence on carcass yield and lean percentage. The effect of halothane (HAL) genotype may interact with environmental factors. Thus, Sather et al. put forward the hypothesis that the dominance-recessiveness relationship for the two HAL alleles (N and n) would depend on the slaughter weight of market pigs. Today, the DNA-based genotyping test for the skeletal muscle ryanodine receptor gene, greatly facilitates the achievement of accurate within-population comparisons between the three halothane genotypes (NN, Nn, and nn). In recent studies using DNA-based genotyping, but involving only NN and Nn pigs, Garcia-Macias et al. and Leach et al. found no significant halothane genotype by slaughter weight interaction. This work aimed to compare the NN, Nn, and nn halothane genotypes, as determined by a DNA-based test, among pigs sharing the same polygenic background (Pietrain x Large White F2 cross) and slaughtered at either of two live weights (around 95 kg or 125 kg), thus bracketing the current average slaughter weight of French market pigs (105-110 kg), to study slaughter weight x HAL genotype interaction.
The experiment involved six halothane-positive (HP) and six halothane-negative (HN) pigs of about 100
kg liveweight. Under general anaesthesia the
tibialis cranialis was exposed. The temperature of ...the muscle was maintained at either 35 or 40°C (
in situ). The muscle was stimulated via the peroneal nerve at 0·1
Hz for 10
min then 1
Hz for 10 further min. Twitch contractions were recorded throughout the stimulation, after which the muscle was excised and split into two parts which were kept in paraffin oil at either 35 or 40°C (post-excision temperature) for 2
h. Samples were taken just before and after the 20
min stimulation period, and at 1 and 2
h after muscle excision for determination of pH and concentrations of PC, ATP, IMP, glycogen, G-6-P and lactate. As soon as one muscle was removed, the operation was repeated on the other leg. Both temperatures (35 and 40°C) were applied to each animal in a balanced design. However data were obtained from only 11 pigs at 40°C as one HP pig died accidentally at the beginning of the 40°C experiment.
Halothane sensitivity influenced the
pH value and the levels of PC, G-6-P and lactate of the muscle
in situ (
P < 0·01 in all cases). Temperature affected contrction time (
P < 0·01). Both halothane sensitivity and Post-excision temperature affected the
pH values and the levels of PC, ATP, IMP, G-6-P and lactate (
P < 0·01 in all cases) in the excised muscle. By contrast, the
in situ temperature treatments did not affect any of the muscle traits measured after excision. It was concluded that the effects of the various treatments on the rate of metabolism in the excised muscle were wholly explainable in terms of temperature from the time of excision, and that the
in situ temperature treatments may not be responsible for the differences after excision.
Two-dimensional electrophoresis was used to investigate sarcoplasmic protein expression in pig Semimembranosus muscles sampled 20 min after slaughter. Two groups (light and dark) of 12 animals were ...selected from 1000 pigs, based on meat L* values measured 36 h postmortem. Twenty-two proteins or fragments (p < 0.05) were differentially expressed. Muscles leading to darker meat had a more oxidative metabolism, indicated by more abundant mitochondrial enzymes of the respiratory chain, hemoglobin, and chaperone or regulator proteins (HSP27, αB-crystallin, and glucose-regulated protein 58kDa). Conversely, enzymes of glycolysis were overexpressed in the lighter group. Such samples were also characterized by higher levels of glutathione S-transferase ω, which can activate the RyR calcium channels, and higher levels of cyclophilin D. This protein pattern is likely to have severe implications on postmortem metabolism, namely, acceleration of ATP depletion and pH fall and subsequent enhanced protein denaturation, well-known to induce discoloration. Keywords: Proteomics; pig; Semimembranosus; L* value; GSTO; cyclophilin D
Two experiments were designed to compare the effects of two pig dehairing techniques. In the first experiment, 120 pigs were slaughtered in the same abattoir in five weekly sereis. One half of each ...series was dehaired by singeing (the usual technique in this abattoir), while the other half was dehaired in a scalding-dehairing combination. In the second experiment, 48 pigs were slaughtered in two series, one-half of each series in an abattoir practising singeing, the other half in an abattoir practising scalding. Temperature and pH were measured 30 min after slaughter in the
longissimus lumborum. Meat quality was assessed the day after slaughter in various muscles. One ham was cured and cooked, while the other one was processed by dry-curing. In both experiments, carcass weights and yields were noticeably higher after singeing. Hams were heavier in singed carcasses, but their proportions in the carcasses were little or not at all affected by the dehairing technique. Proportions of loins, shoulders and bellies were similar with both dehairing techniques. The dehairing technique affected neither temperature nor rate of
post-mortem pH fall. Meat quality as assessed on fresh meat was slightly better in singed carcasses. Weights of cooked ham and dry ham per side were higher in singed carcasses, due to the higher initial ham weight, but processing yields were not affected by the dehairing technique.
The halothane genotype of 22 Polish landrace pigs was determined using halothane test and blood typing. Eight homozygous normal (NN), eight hetero-zygotes (Nn) and six homozygous recessive (nn) were ...identified. The levels of glycogen and lactate were measured in biopsy samples taken from the
longissimus lumborum using a shot biopsy technique. pH (pH
1) and IMP/ATP ratio (R) were determined at 30
min after slaughter, while pH, meat colour and water holding capacity were determined on the day after slaughter. The halothane genotype did not affect
intra vitam glycogen level. The nn pigs had a higher R value and lower pH
1 than both Nn and NN animals. Heterozygous animals were intermediate between both homo-zygotes for biopsy lactate level and meat colour. The lactate content of biopsy samples was significantly correlated with pH
1 (
r = −0·68;
P < 0·01), R (
r = 0·68;
P < 0·01), meat colour (
r = 0·57;
P < 0·01) and water holding capacity (
r = 0·45;
P · 0·05).
Les qualités technologiques et sensorielles de la viande bovine que sont l’aptitude à la transformation, le pouvoir de rétention d’eau, la couleur, la tendreté, la jutosité et la flaveur, dépendent ...de plusieurs facteurs biologiques. Cet article tente de passer en revue les principaux de ces facteurs : la localisation anatomique et la fonction physiologique du muscle, le type génétique (race et type culard), l’âge, le sexe, les conditions d’élevage. Il en ressort que parmi les facteurs de variation des qualités de la viande entre animaux, l’âge, le sexe et les conditions d’élevage jouent un rôle primordial, la race n’ayant qu’un effet mineur.
Forty-five Large White barrows were injected daily i.m. with either excipient from 30 to 100 kg BW (CTRL), excipient from 30 to 60 and porcine somatotropin (PST; 100; microgram/kg BW) from 60 to 100 ...kg BW (pST-60), or PST (100 microgram/kg BW) from 30 to 100 kg BW (pST-30). Somatotropin accelerated overall growth rate (+4 and +9% for pST-60 and pST-30, respectively), increased longissimus (+10.3 and +14.7%) and semitendinosus (+17 and +13%) muscle weights, and decreased backfat (-49 and -58%) and leaf fat (-49 and -53%) weights. The administration of PST resulted in a similar increase in muscle fiber size for all fiber types in both longissimus (LM) and semispinalis (SS) muscles (+21%). Somatotropin had otherwise little effect on muscle fiber types and biochemical traits of LM, whereas dramatic changes were observed in SS. The relative area occupied by Type IIB fibers was increased (+22 and +29%) and that of Type I fibers was decreased (-l0 and -15%). In PST-30 animals, myosine ATPase activity (+15%) and native myosin fast isoform proportion (+l0%) were augmented, and energy metabolism was more glycolytic (lactate dehydrogenase: +25%) and less oxydative (citrate synthase: -13%; beta-hydroxy-acyl-CoA acyl-CoA dehydrogenase: -2l%). Compared to CTRL animals, administration of PST increased muscle water concentration (LM: +.8 and + 1.1%: SS: +3.3and +3.3%) and decreased intramuscular fat (LM: -29 and -27%; SS: -39 and -50%). The pH measured 45 min and 24 h postmortem, glycogen content, reflectance, and index of light diffusion were mostly not affected by PST treatment. In conclusion, PST had a very favorable effect on growth performance without any important effect on meat quality traits except for the reduction in intramuscular lipid content. The results indicated that the effects of PST on muscular histochemical and biochemical characteristics were different in LM and SS muscles
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