Effects of dietary components including garlic on concentrations of skatole and indole in subcutaneous fat of female pigs

The results reported here showed that threshold concentrations of skatole and indole in rice-bran oil for Singaporean consumers were 0.028 μg/g and 0.051 μg/g, respectively, and that skatole and indole levels in subcutaneous fat of pigs can be affected by diet. In Experiment A, 31 female pigs were fed with diets based on plant products only (P) or plant plus animal by-products (AP), with added levels of garlic essential oil from zero to 2.15 g/kg feed. Concentrations of skatole and indole increased with increasing garlic concentration (P < 0.001). In Experiment B, P and AP diets were fed to 47 female pigs with different dietary lipid sources (fish oil, tallow, and a mix of linseed oil and soya oil). Skatole and indole concentrations were higher in backfat of pigs fed with the AP diet (P < 0.05), but were unaffected by the type of lipid.     

Elastin in bovine Semitendinosus and Longissimus dorsi muscles

The structural organization of elastin present in bovine semitendinosus and longissimus dorsi muscles was examined using light and scanning electron microscopy. Qualitatively, both muscles were found to have the same organization of the two structural forms of elastin present.

Coarse elastin fibres (5–10 μm diameter) were found in the epimysium and perimysium, aligned with the long axis of the muscle fibres. In addition, finer elastin fibres (1–2 μm diameter) were found in the epimysial and perimysial sheets of collagen. These finer elastin fibres approximated the course of the collagen fibres, i.e. at an angle to the muscle fibre long axis.

Quantitatively, the semitendinosus muscle epimysium and perimysium contained very heavy deposits of the coarse elastin fibres and nearly every sheet of perimysium, even the thinest, contained the fine elastin fibres. By comparison, less of the coarse elastin was present in the longissimus dorsi epimysium and it was quite rare in the perimysium. The finer elastin fibres were, however, reasonably common.

The significance of this structural arrangement is discussed in relation to muscle function and to meat toughness assessment.     

Histo- and biochemical characteristics of the Longissimus dorsi muscle in pigs and their relationships to performance and meat quality

Histo- and biochemical characteristics of the longissimus dorsi muscle at 65–70 kg body weight and their relationships to performance and meat quality at 100 kg were examined in Danish Landrace and Danish Large White female and castrated male pigs. Breed differences were observed for feed conversion rate, and a number of histochemical and biochemical traits. The organoleptic traits, flavour (13%), tenderness (15%) and overall acceptability (13%) were rated higher in Large White pigs. Significant correlations between histological and biochemical traits of the live muscle on the one side and performance, meat quality and organoleptic traits on the other side, could be demonstrated. However, these correlations were generally low (r < 0.35), and can thus only explain a small part of the variation in the measured quality traits. Consequently live muscle traits measured at 65–70 kg are poor predictors of meat quality characteristics after slaughter at 100 kg.     

Protein and lipid oxidation in Longissimus dorsi and dry cured loin from Iberian pigs as affected by crossbreeding and diet

Lipid and protein oxidation in Longissimus dorsi (LD) and dry-cured loins from pigs with different genetic (pure Iberian (IBP), Iberian female × Duroc male (IB × D) and Duroc female × Iberian male (D × IB)) and feeding backgrounds (free rearing on acorn and pasture (MON), concentrates high in oleic acid and supplemented with 250 ppm of vitamin E(HOVE) and control concentrates (CON)) were investigated. Diet influenced the fatty acids profile from PL and α- and γ-tocopherol contents of LD. IBP–MON pigs showed the lowest malonaldehyde (MDA) values at 200 min of iron induced muscle oxidation. Dry-cured loins from IBP–HOVE pigs had significantly (p < 0.05) higher values of TBARS than those from the other batches. Neither the diet nor crossbreeding affected hexanal counts in dry-cured loins. Protein carbonyl content showed a similar trend to that observed for MDA values in LD, suggesting a protective role of tocopherol against lipid and protein oxidation. The positive and significant correlations between iron induced lipid oxidation in LD (200 min) and carbonyl content in LD and dry-cured loin (R²: 0.55 and R²: 0.52, respectively, p < 0.01) support the relationship between lipid and protein oxidation.     

Cold-shortening toughness in excised pork M. Longissimus dorsi

Excised pork M. Longissimus dorsi from six Large White Cross pigs were subjected to a range of chilling rates using temperatures between 20°C and -20°C. Onset of rigor at 20°C varied from 3 to 7.5 h between animals and rigor was complete in 6.5 to 15 h. Cold-shortening was induced when samples were chilled in air or liquid at 3°C or below but not at 5°C or ambient. The highest cooling rate, using liquid at -1°C, reduced the meat samples to 10°C in about 1 h and induced 34% shortening. After ageing for 5 days at 3°C in 26 h. Considering all chilling rates, toughness increased as the time to reach 10°C decreased to 3 h or less. Extensive cold-toughening would be unlikely to occur in current UK commerce and any toughening which did occur would be confined to Longissimus dorsi M. in about 20% of carcasses. The projected increased introduction of very rapid cooling, particularly in conjunction with lean pig production and hot deboning of pork, could toughen all cuts in about 60% of carcasses.     

Fatty acid composition of lipid in Longissimus dorsi muscle of Duroc and British Landrace pigs and its relationship with eating quality

The fatty acid composition of intramuscular fat from Duroc and halothane negative British Landrace pigs was determined and the relationships between fatty acid concentrations and aspects of eating quality were estimated from data on 160 pigs. Boars and gilts from each breed were performance tested on ad libitum or restricted feeding regimes with an average slaughter weight of 80 kg. Eating quality was assessed by ten experienced taste panelists.

Intramuscular fat of Duroc pigs had higher concentrations of saturated and mono-unsaturated fatty acids and lower concentrations of poly-unsaturated fatty acids than Landrace pigs. With increasing intramuscular fat content, concentrations of saturated and mono-unsaturated fatty acids increased and concentrations of poly-unsaturated fatty acids decreased and the rate of change in fatty acid concentrations was greater in Landrace pigs than in Duroc pigs.

Eating quality traits were generally improved as the concentration of mono-unsaturated fatty acids increased and poly-unsaturated fatty acids decreased.     

Determinants of tenderisation in beef Longissimus dorsi and Triceps brachii muscles

Tenderisation of bovine Mm. longissimus dorsi and triceps brachii and factors impacting tenderisation were studied. Mm. longissimus dorsi and triceps brachii of 12 Friesian-Holstein cows (age 3-11 years; 212-349 kg carcass weight) were sampled at various times post mortem (p.m.) for determination of pH, temperature, fibre type and morphology, connective tissue distribution, SDS-PAGE of myofibrillar proteins, Warner-Bratzler shear force, sarcomere length and osmolality. The stretched position of the M. triceps brachii (sarcomere length 2.35 ± 0.24 μm) resulted in a relatively low shear force at 1 day p.m. (6.2 ± 0.9 kg/cm(2)) with further storage having little additional effect. M. longissimus dorsi entered rigor in a more contracted state (sarcomere length 1.65 ± 0.11 μm), resulting in a relatively high shear force at 1 day p.m. (10.3 ± 2.3). Stepwise linear regression was used to calculate the best 1- to 3-variable equations for shear force of M. longissimus dorsi at 1, 7 and 14 days p.m. and the decrease in shear force between 7 and 14 days p.m. Shear force at 1 day p.m. appeared to be determined mainly by the speed of pH- and temperature-decline. Proteolysis of myofibrillar proteins and animal age appeared to be the main determinants for shear force at 1 and 14 days p.m. The average surface area of type I fibres could explain part of the variation in the decrease in shear force between 1 and 14 days p.m.     

Post-mortem glycolysis in rabbit Longissimus dorsi muscles following electrical stimulation

The effects of both high voltage and low voltage electrical stimulation were studied in rabbit Longissimus dorsi muscles. The rate of fall of pH as well as the activities of phosphorylase a, phosphorylase kinase, and phosphorylase phosphatase were measured. The effects on the yield, ATPase activities, and calcium permeability of the sarcoplasmic reticulum (SR) were also measured. Although only high voltage stimulation increased the post-stimulation rate of pH fall, both types of electrical stimulation increased the phosphorylase a activity, apparently by increasing the activity of phosphorylase kinase and destroying a large part of the phosphorylase phosphatase activity. Electrical stimulation reduced the yield of SR and increased its basal ATPase activity. It also increased the ability of the SR to retain accumulated calcium. We conclude that the different rates of pH fall observed following the two types of stimulation are due to the differential effects of these treatments on one of the ATPase activities, probably the myofibrillar ATPase.     

Fibre types in Longissimus dorsi from wild and highly selected pig breeds

Longissimus dorsi muscles from six pig breeds were examined histologically. It was found that mean fibre diameter increased with degree of selection in domestic pigs and that the percentage of red fibres decreased—i.e. from Mangulica and Black Slavonian to Large White and Swedish Landrace. The percentage of white fibres showed the reverse tendency whilst that of the intermediate type was not markedly changed. In semi-wild pigs, the percentage of red fibres was still higher and in forest pigs there were neither white nor intermediate fibres in longissimus dorsi. Beneath the sarcolemna of red fibres there was a significantly higher number of mitochondria than in the central parts of the fibre.

The distribution of the ‘giant fibres’ indicated that this formation may be found in the muscles of both stress-susceptible and stress-insusceptible pigs.     

The relationship between ATP and R-values in postmortem bovine Longissimus dorsi muscle

To study the relationship between ATP and each of three R-values (R248, R250 and R258) in beef longissimus dorsi muscle data, appropriate mathematical functional forms were estimated by the Box-Cox transformation and then tested for linearity. Two separate tests for linearity indicated that the relationships between ATP and the three R-values were nonlinear. A shifting parameter restriction on the Box-Cox model was used to produce a curve that was more parallel to the y axis in the lower range of x axis, but the restriction lowered the R(2) compared with the Box-Cox model. ATP (1 μmol) could be estimated by R248 of 0·925, R250 of 0·967 and R258 of 1·038 with standard errors of 0·033, 0·034 and 0·032, respectively. There were no significant differences among the three R-values for the prediction of ATP, but there was a suggestion that R258 was the preferred R-value for predicting ATP in beef muscle.     

快速冷却对兔肉背最长肌肉品质的影响

为探讨快速冷却对兔肉食用品质的影响,选取24只獭兔进行屠宰,取背最长肌,按试验设计进行快速冷却和常规冷却处理后测定肉品质相关指标。结果表明：快速冷却(－12℃±1℃,30min;0～4℃储藏至24h)能加快兔肉温度下降速率,减缓pH值下降速率;使肉色泽改善,提高肉的保水性;成熟7d内显著降低肌肉脂肪氧化,但对兔肉的嫩度没有影响。     

Variation in light scattering and water-holding capacity along the porcine Longissimus dorsi muscle

The meat quality of M. longissimus muscle was evaluated in 851 pigs by using the Fibre Optic Probe (FOP) at three sites in the muscle and in both halves of the carcass. A systematic difference between sites was found, with the lowest light scattering (indicating the best meat quality) in the mid-part of the muscle and higher light scattering in the anterior and posterior parts. A non-systematic variation was also observed, with the opposite pattern in some animals, even though it was not frequent. A negative influence of the shackling was found, yielding higher FOP values in the shackled half.

Drip loss measurements in the Longissimus muscle, taken from another 100 pig carcasses, were evaluated using three methods. Drip loss, too, showed a considerable variation along the Longissimus muscle, with minimum losses around the last rib. Repeatability estimates, calculated from two non-consecutive pieces of the Longissimus dorsi muscle from each carcass, varied from 0·4 when keeping samples vacuum packed for 2 days, to 0·5 when the samples were either kept in plain plastic bags for 2 days or in a meat container with a squared inset for 1 or 2 days.     

Physico-chemical characteristics of M. Longissimus dorsi from three lines of free-range reared Iberian pigs slaughtered at 90 kg live-weight and commercial pigs: a comparative study

Longissimus dorsi muscles from three lines of Iberian pig and those from commercial pigs were analysed in order to evaluate their quality for fresh consumption. Iberian pigs were reared in a natural outdoor production system with access to grass, while m. Longissimus dorsi from commercial pigs were procured from a local slaughterhouse. Iberian pigs’ Longissimus dorsi showed a higher fat (P<0.05) and lower phospholipid contents (g PL/g fat; P<0.05) than Longissimus dorsi from commercial pigs. Iberian pigs’ Longissimus dorsi muscles had a higher content of haem iron (P<0.05) than those from commercial pigs and consequently m. Longissimus dorsi exhibited a redder colour (higher a*-value) that diverged less from the true red axis (lower hue value; P<0.05) than those from commercial pigs which resulted paler (higher L*-value; P<0.05). Total fat and neutral lipid fatty acid profiles showed higher percentages of palmitic, oleic, total saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) m. Longissimus dorsi of Iberian pigs than in the commercial ones (P<0.05). m. Longissimus dorsi from the commercial pigs contained higher proportions of polyunsaturated fatty acids and a higher n-6/n-3 ratio value (P<0.05).     

Stunning and shackling influences on quality of porcine Longissimus dorsi and Semimembranosus muscles

Seventy-one barrows of three porcine genotypes (nn, Nn and NN genotypes with respect to halothane) were electrically stunned on the right side and randomly assigned to one of three treatments during the bleeding process (prone, PR; shackled left, SL; or shackled right, SR) to investigate the influence of both shackling and stunning on ultimate meat quality. PR carcasses had less side-to-side variation in 40 min pH than either SL or SR carcasses. Shackling contributed to a decreased 40 min pH in the semimembranosus (SM) and posterior longissimus dorsi (PL). The effects of stunning appeared to be additive when combined with shackling, tending to lower pH in the mid-longissimus dorsi (ML; P <- 0·10). The ‘free’ side of the shackled carcass also had significantly lower 40 min pH in the ML, PL and SM locations when compared to PR sides. Genotype had no influence on shackling since there was no treatment by genotype interactions. Despite significant effects on post-mortem metabolism (indicated by the differences in 40 min pH) shackling alone had little influence on overall ultimate meat quality of the carcass. Depending on the sampling location, soluble protein and L^* and b^* values varied among treatments. Shear force and a^* values were similar among treatments, but PR and SL carcasses had significantly lower expressible juice and drip loss compared to SR carcasses. These results suggest that, although shackling alone has little effect on meat quality, in combination with electrical stunning, shackling can lead to a decrease in meat quality.     

Release of major ions during rigor mortis development in kid Longissimus dorsi muscle

Ionic strength plays an important role in post mortem muscle changes. Its increase is due to ion release during the development of rigor mortis. Twelve alpine kids were used to study the effects of chilling and meat pH on ion release. Free ions were measured in Longissimus dorsi muscle by capillary electrophoresis after water extraction. All free ion concentrations increased after death, but there were differences between ions. Temperature was not a factor affecting ion release in contrast to ultimate pH value. Three release mechanisms are believed to coexist: a passive binding to proteins, which stops as pH decreases, an active segregation which stops as ATP disappears and the production of metabolites due to anaerobic glycolysis.     

Changes in pH and water holding properties of Longissimus dorsi muscle during beef ageing

The effects of vacuum packaging, chilling rate (slow or fast), and fat cover thickness (≤ 4 mm or 7–8 mm) on pH and water-holding properties of longissimus dorsi muscle were assessed during beef ageing. The longissimus dorsi muscles were aged on the carcass or in vacuum packaging. Muscle samples were taken on days 0 (24 h post-mortem), 2, 4, 8, 12 and 16 to measure these properties. Ageing time significantly influenced muscle pH and cooking loss; however, interaction fat × chill × time affected press juice. The pH was also influenced by vacuum-packaged ageing. Press juice positively correlated with cooking loss and pH.     

Study of variability in antioxidant composition and fatty acids profile of Longissimus dorsi and Serratus ventralis muscles from Iberian pigs reared in two different Montanera seasons

This investigation was designed to evaluate the effects of variations in antioxidant and fatty acids composition of acorns and grass from two Montanera (free-range system and feeding based on acorns and grass) seasons (2006/07 and 2007/08) on the antioxidant composition and fatty acids profile of m. Longissimus dorsi (LD) and m. Serratus ventralis (SV) from Iberian pigs reared under these Montanera seasons. Acorn and grass composition was affected by Montanera season and consequently, LD and SV muscles showed different contents of α-tocopherol, total phenols, hydrophilic and lipophilic antioxidant activity and fatty acid profile, according with the composition of acorns and grass ingested. Results suggest a lack of uniformity in meat quality between different seasons. This could be due to the variable nature of extensive pig production as reflected in the variability in the composition of the diet (acorns and grass).     

快速冷却对山羊背最长肌肉品质的影响

6头云南地方云岭黑山羊(羯羊)屠宰、劈半后,左半胴体进行常规冷却(0～4℃冷却24h,相对湿度90～95%),右半胴体进行快速冷却(-20℃,冷却1.0h后,转入0～4℃冷却23h,相对湿度90～95%),取背最长肌,测定相关肉品质指标。结果显示,样品经3d成熟,快速冷却的羊肉剪切力显著低于常规冷却(P<0.05),快速冷却的羊肉嫩度的感官评分显著高于常规冷却(P<0.05),而pH、肉色、蒸煮损失等指标两种冷却方式无显著差异。研究表明,本试验采用的快速冷却方式对山羊肉的嫩度有显著改善效果。     

Heat-induced changes in the proportion of types I and III collagen in bovine Longissimus dorsi

Intramuscular collagen (IMC) was isolated from the Longissimus dorsi of six Simmental bulls, 17 months of age, to evaluate the effect of heating on the proportion of types I and III collagen. Cyanogen bromide (CNBr) peptides were prepared from unheated IMC and the soluble and insoluble fractions of IMC heated to 70°C for 70 min or 90°C for 140 min. Percentage of type III collagen was determined by densitometric scans of the CNBr peptides, αl(I)CB8 and αl(III)CB8, as resolved by SDS-PAGE. Percentage of collagen solubilized was greater (P < 0·05) at 90°C than at 70°C. The 70°C and 90°C insoluble IMCs were similar (P > 0·05) for percentage of type III, but both had a greater (P < 0·05) percentage of type III than unheated IMC, indicating that type I is more heat labile than type III. Heat-soluble IMC contained both α and β components and the CNBr peptides of 70°C soluble IMC were mostly type I. These results indicated that heating intramuscular collagen from bulls mainly solubilized type I collagen. Improved tenderness associated with increased heat solubility of collagen may be more closely related to heat-induced solubilization of type I than of type III collagen.