Pork Meat Quality Research Articles

FAT THICKNESS AND LOIN EYE AREA EFFECTS ON PORK CARCASS QUALITY MEASURES

ABSTRACT Pork carcasses (n = 133), varying in fatness and muscling, were selected to evaluate the relationship between pork carcass cutability and pork meat quality. Carcasses were selected with three levels of 10th rib fat (TRBF: < 2.03 cm, n = 60; 2.03 ‐ 2.54 cm, n = 31; and > 2.54 cm, n = 42) and three levels of loin eye area (LEA: < 35.5 cm2, n = 33; 35.5 – 41.9 cm2, n = 52; and > 41.9 cm2, n = 48). Data were collected on the longissimus muscle of ribbed carcasses. Carcasses in the leanest TRBF group had less (P < 0.05) marbling, and softer (P < 0.05) and more watery (P < 0.05) lean than the fatter categories. Carcasses in the leanest category were also redder in color (P < 0.05; higher a* values) than the fattest category. Carcasses in the smallest LEA group had higher (P < 0.05) marbling and firmness scores than the largest LEA group and carcasses in the largest LEA group had more (P < 0.05) exudative loin muscles than the remaining LEA groups. Collectively, these data indicate that selection for reduced carcass fatness and increased carcass muscling, in swine, has significant negative effects on pork meat quality.

Relationships between (1)H NMR relaxation data and some technological parameters of meat: a chemometric approach.

In this paper chemometrics (ANOVA and PCR) is used to measure unbiased correlations between NMR spin-echo decays of pork M. Longissimus dorsi obtained through Carr-Purcell-Meiboom-Gill (CPMG) experiments at low frequency (20 MHz) and the values of 14 technological parameters commonly used to assess pork meat quality. On the basis of the ANOVA results, it is also found that the CPMG decays of meat cannot be best interpreted with a "discrete" model (i.e., by expanding the decays in a series of a discrete number of exponential components, each with a different transverse relaxation time), but rather with a "continuous" model, by which a continuous distribution of T(2)'s is allowed. The latter model also agrees with literature histological results.

Low stress pre-slaughter handling: effect of lairage time on the meat quality of pork

The effect of lairage time on meat quality was investigated when crossbred pigs were subjected to low stress pre-slaughter handling, where pigs were treated in mixed groups of 15 from the farm to group CO 2 stunning, and where electric goads were not used at any time. Two experiments were carried out, one in spring ( n=270) using very standardised conditions and one producer, and one in summer ( n=630) using a representative randomly chosen sample of producers. In the first experiment three lairage times were used, less than 30 min (average 26 min), 90 min (average 83 min) and more than 150 min (average 170 min) and no showering. The pH and temperature were measured in the m. longissimus dorsi at various times post mortem, and colour ( L * , a * , b * ), internal reflectance and drip loss the day after slaughter. Sensory evaluation was carried out on 16 randomly chosen samples from the shortest and longest lairage time groups. Drip loss, pH ultimate and internal reflectance were also measured in the m. biceps femoris and pH ultimate and internal reflectance in the m. semimembranosus. Finally, pH ultimate was measured in the m. semispinalis capitis. In the second experiment only two lairage times were used, less than 30 min (average 17 min) and more than 130 min (average 150 min) and with intermittent showering and only a subset of the meat quality measurements were made. Lairage time had no effect on any of the meat quality parameters measured in experiment 1. In experiment 2 the shortest lairage time led to a higher temperature in the m. longissimus dorsi at 2 min post mortem, a higher drip loss in the m. biceps femoris and higher internal reflectance values in both muscles the day after slaughter. The differences were, however, very small and may have been an effect of showering.

The use of muscle enzymes as predictors of pork meat quality

Muscle endo-protease (calpains and cathepsins) and exo-protease (dipeptidyl-peptidases and aminopeptidases) activities were assayed at 2 h post-mortem in different meat qualities (PSE, RSE, RFN and DFD). The sensory characteristics of the different pork meat qualities were also evaluated in order to correlate them to the proteolytic activity. The assay of aminopeptidase and dipeptidylpeptidase activities (AAP, RAP, LAP, DPPI and DPPIV) at 2 h post-mortem discriminate between exudative and non-exudative classes explaining 74.6% of the variability. Also, at 24 h post-mortem 71.2% of the variability was detected by the measurement of PGAP, AAP, RAP, DPPII and DPPIV. Therefore, the exoprotease activities can constitute a novel and adequate technique to predict early post-mortem pork meat quality allowing its assay till 24 h post-mortem because of the good stability of the enzymes during this post-mortem time.

Nitrogen compounds as potential biochemical markers of pork meat quality

Muscle proteins, peptides and free amino acids were analysed at 2 h post-mortem as potential markers of different pork meat qualities. The meat quality classification was based on the measurements: pH 2h, pH 24h, the colour parameter L, and drip loss. The measurement of proteolytic fragments by SDS-PAGE revealed that the nebulin band was different among classes being more defined in the dark, firm and dry meat class. The detection and characterisation of small peptide fragments resulting from protein breakdown was done by isolation through cationic and reverse-phase chromatography. The analysis of peptide fractions isolated by reverse-phase chromatography revealed that could be used as potential markers of meat quality. So, peptide fraction 1 could be used to distinguish exudative from non-exudative meats and peptide fraction 4 distinguished dark, firm and dry meat from the rest. The concentration of free amino acids present in muscle was not different among qualities, probably due to the early post-mortem time (2 h) used in the study.

Historical perspectives and current aspects of pork meat quality in the USA

The condition of pale, soft and exudative (PSE) pork meat was recognized and documented by 1960, and the condition of porcine stress syndrome (PSS) was understood within the decade of the 1960s. The two are associated, with PSS animals having a high probability of producing PSE meat. Both are economically important with potential death losses, especially during transport, due to PSS, and PSE meat being viewed as of inferior quality by consumers and also having less value for further processing. An enormous amount of research has been directed at the problem and is presented in the manuscript as a time-line approaching a half-century of effort. Surveys of incidence showed, in pork produced in the USA, that 18% was PSE in 1963 and 16% was PSE in 1992. Fortunately, molecular/genetic understanding and tools are now available to attack the problem, but solving it may require further impetus — such as strong and unified resolution by producers, industry associations and governmental agencies.

The use of gene technology for optimal development of pork meat quality

The aim of this paper is to discuss the opportunities for gene technology in relation to the quality of pork. After dealing with breed effects and within-breed variation, an overview of major genes and DNA technology is given. It is demonstrated that some of the breed effects can be fully explained from the presence of a single gene with major effect. Within breeds, there is considerable genetic variation in relevant meat quality traits like waterholding capacity and intramuscular fat. Again, part of this variation is due to major genes. As a result, DNA marker technology can play an important role in improving meat quality. Selective breeding based on this technology will also increase the uniformity of the final product. Furthermore, the exploitation of major genes can be highly relevant for differentiation of breeding populations for specific markets.

The influence of breed, gender, and PSS (Halothane) genotype on meat quality, cooking loss, and palatability of pork

A total 851 swine of four breeds (Duroc, Hampshire, Landrace, and Yorkshire), three genders (barrows, gilts, and boars) and two PSS (halothane) genotypes (carriers and non-carriers of the halothane gene) were evaluated for meat quality, cooking, and palatability traits. Breed exerted a major influence on meat quality, cooking, and palatability traits. The most palatable meat was produced by Hampshires and the least desirable meat was produced by Yorkshires. Although juiciness was negatively correlated with cooking loss ( r=−0.60), meat from Hampshires received the highest ratings for juiciness, despite sustaining the greatest cooking losses. Gender exerted minor influences on meat quality and palatability attributes, and no indication was obtained genders differed sufficiently in palatability to warrant discrimination based upon gender. Therefore, entire males can be utilized to capitalize on reported production advantages without influencing palatability, particularly if adequate means for screening boar taint are available for carcasses from heavier or more mature animals. Halothane genotype exerted substantial influence on meat quality traits and statistically significant but relatively minor influence on palatability traits. Carriers of the halothane gene produced meat which was of clearly inferior quality to the meat produced by non-carriers. Carriers of the halothane gene consistently produced a higher proportion of unacceptable chops than non-carriers, although differences were not statistically significant.

Effects of Dietary Rape Seed Oil, Copper(II) Sulphate and Vitamin E on Drip Loss, Colour and Lipid Oxidation of Chilled Pork Chops Packed in Atmospheric Air or in a High Oxygen Atmosphere

The effect of addition of rapeseed oil (canola), CuSO 4 and vitamin E ( all-rac-α-tocopheryl acetate) to pig diets on pork meat quality (lipid oxidation, colour and drip loss) was studied. Pigs were reared on ten different diets, either a control diet (no supplementation of rapeseed oil, CuSO 4 or vitamin E) or 6% rapeseed oil diets supplemented with CuSO 4 (0, 35 or 175 mg/kg) and vitamin E (0, 100 or 200 mg all-rac-α-tocopheryl acetate/kg). The natural content of vitamin E originating from feed ingredients amounted to 9–23 mg vitamin E (α-tocopherol) per kg feed. Muscle vitamin E levels reflected the dietary intake and pigs fed the control diet had significantly lower levels than pigs fed rapeseed oil diets. The quality of fresh pork chops packed in air or in 80% O 2:20% CO 2 was followed during chill storage for 8 and 13 days, respectively. Colour, as measured by tristimulus colorimetry of pork chops packed in 80% oxygen atmosphere, was significantly improved with respect to redness when compared to chops packed in air, regardless of dietary treatment. The low vitamin E content in pigs fed the control feed significantly decreased a values and the oxidative stability of pork chops during chill storage compared to the other feeding groups. Packing of chops in a high-oxygen atmosphere increased lipid oxidation, especially in chops with low levels of vitamin E. Supplementation of rapeseed oil diets with 100 or 200 mg vitamin E significantly decreased lipid oxidation of chill stored chops. Supplementation with CuSO 4 did not influence meat quality attributes (drip loss, colour stability and lipid oxidation) for any of the storage conditions.

Preservative Effect of Combined Propionic and Ascorbic Acids on Pork Meat Stored at 25°C

A potential method for improving the bacteriological quality of pork meat stored at the ambient temperatures found in developing countries has been studied. Raw minced pork (longissimus dorsi muscle) was treated with propionic acid alone and propionic and ascorbic acid in combination at concentrations that had a preservative effect, restricting populations of pathogenic and spoilage bacteria well below thresholds necessary for spoilage or damage to public health. A water-treated sample was used as the control. The 0.306 mol/liter propionic -0.043 mol/liter ascorbic acid combination reduced bacterial numbers for up to 8 days at 25 ± 1°C, without adversely affecting the color or odor of the meat. Minced pork treated with solutions of propionic acid at 0.136 and 0.410 mol/liter showed surface bleaching and an increase in lipid oxidation volatiles relative to the water-treated control sample.

Microbiological quality of pork meat from local Hong Kong markets

Over a 3-week period, samples of fresh, chopped, pork meat were taken every morning and afternoon from 50 meat stalls. Microbiological examination revealed that the samples had (c.f.u./g): total microbes, 1×10(3) to 2.14×10(6); mean probable numbers of coliforms and Escherichia coli, 1.51×10(3) to 1.15×10(4); and yeasts and moulds, 0 to 1.28×10(4). Salmonella, found in 32 samples from 21 stalls, were serotyped as B (three samples), C1 (four) or E (25). No Campylobacter were found. Because microbial growth and/or contamination of the meat occurred during the day, samples taken in the afternoon had greater total counts (P<0.05) and contained detectable numbers of Salmonella more frequently (42% versus 22%) than those taken in the morning.

On-line methods for pork quality detection

The detection of pale, soft, exudative (PSE) and dry, firm, dark (DFD) meat is one of the most important problems in judging pork quality. The use of PSE meat leads to lower yields and changes in the rate of salt penetration in cured products, and is unsuitable for preparing cooked products while DFD meat has only a limited application in the preparation of cured products and is easily contaminated by microbial growth. For this reason it is important to be able to detect pork meat quality soon after slaughter and, to aid in this task, ‘on-line’ probes have been developed which are capable of rapidly categorizing meat. Most of these probes are based on the optical and electrical properties of muscle. The most interesting are those which measure internal light scattering by fibre optic probe (FOP) and electrical conductivity by quality meter (QM). Pork quality was studied using FOP, QM and pH measurement on the slaughter line in semimembranosus (SM) and longissimus dorsi (LD) muscles at 45 min and 24 h post-mortem. Results showed that pH is a good predictor of meat quality at 45 min and 24 h post-mortem while FOP differentiates between extreme categories and QM is better at detecting PSE meat.

The effect of mixing, feed restriction and genotype with respect to stress susceptibility on pork carcass and meat quality

The effects of genotype for stress susceptibility with respect to the halothane gene (PSS genotype: NN = homozygous normal, Nn = heterozygous, nn = homozygous recessive), in combination with fasting and mixing during the 24 h prior to shipping for slaughter upon the carcass traits and quality of the longissimus muscle were investigated using a total of 229 pigs. In comparison to pigs of the NN genotype, pigs of the nn genotype had higher warm carcass yield, cold carcass yield, yield of the major cuts and lean yield of the major cuts by 47, 39, 5 and 15 g kg−1, respectively. Pigs of the Nn genotype had 30 and 8 g kg−1 higher warm carcass yield and yield of major cuts, respectively, than did NN pigs. Pigs of the nn genotype had 178 g kg−1 and pigs of the Nn genotype had 66 g kg−1 more total lean in the major cuts than NN pigs but these differences were not detected by the carcass grading system. Mixing and fasting both caused live-animal weight losses and reduction of warm carcass yield. Fasting had the greater influence, decreasing live animal weight by 54 g kg−1 and the warm carcass yield by 12 g kg−1 in comparison to the unmixed, unfasted pigs. Combined fasting and mixing for 24 h decreased live animal weight by 62 g kg−1 and the warm carcass yield by 19 g kg−1 in comparison to the unmixed, unfasted pigs. Pigs of both nn and Nn genotypes produced poorer muscle quality than did those of the NN genotype. Fasting of pigs for 24 h pre-slaughter alleviated the PSE problem to a small extent. Mixing, with or without fasting, improved muscle quality of pigs of the Nn and nn genotypes. However, such gains in meat quality due to mixing and/or fasting are negated by the decreases in the carcass yield, by the additional carcass damage due to fighting and finally by their possible detriment to animal welfare. Key words: Mixing, fasting, halothane genotype, carcass, pork quality, pigs

Effects of exogenous porcine somatotropin (pST) administration on pork meat quality

Two experiments were conducted on Large White pigs in order to assess the effect of porcine somatotropin (pST) administration upon meat quality criteria. No clear trend was observed concerning pH1 or pH2 measurements in Longissimus dorsi (LD), Adductor femoris (AF) and Semi spinalis (SS) muscles or drip loss in LD. Cooking loss in LD was not affected by pST treatment. Intramuscular lipid content was decreased by pST in LD and AF. Only non-polar lipids were affected by pST, whereas polar lipid content was similar in control and pST treated pigs. Percentage polyunsaturated fatty acids was significantly increased by pST in backfat and LD lipids, whereas no clear trend was observed concerning fatty acid composition of AF lipids.

The effect of the halothane gene on pork production and meat quality of pigs reared under commercial conditions

Production and meat quality traits were evaluated on 74 commercially raised heterozygous pigs (Nn) and 50 homozygous normal pigs (NN) at the halothane locus, with an average carcass weight of 79.7 kg. Eight-week weight, average daily gain and age to market, as well as measures of carcass quality (i.e., dressing percent, grade site fat and muscle depths and predicted lean yield) did not differ among pigs with Nn and NN genotypes. The longissimus dorsi muscle from Nn and NN pigs had similar subjective colour and structure scores. Reflectance meter readings (CIE L*-values) were significantly higher on chops from Nn than from NN pigs taken from the centre (57.4 vs. 55.6) and from the anterior portion (56.2 vs. 54.5) of the loin. Drip loss among Nn pigs was higher than among NN pigs for chops taken from the centre (4.8 vs. 3.8 g 100 g−1) and from the anterior portion (3.7 vs. 2.9 g 100 g−1) of the loin (P &lt; 0.01). Soluble protein was 1.7% lower (P &lt; 0.001) in Nn pigs compared with the NN pigs. Barrows attained market weight earlier (P &lt; 0.05) than gilts, but they had a lower dressing percentage (P &lt; 0.05) and greater grade fat depth (P &lt; 0.001) and had 1.2% less predicted lean yield of carcass (P &lt; 0.001) than gilts. Since meat quality declined without concomitant increases in growth rate or improvements in carcass quality, it was concluded that the intentional use of the halothane gene should be discouraged. Key words: Swine, production, carcass quality, meat quality, halothane gene

Effects of exogenous porcine somatotropin (pST) administration on growth performance, carcass traits, and pork meat quality of Meishan, Pietrain, and crossbred gilts1

Seventeen to twenty-three females of lean (Pietrain, PI), fat (Meishan, MS), or intermediate genotype (PI x [3/4 Large White x 1/4 MS]), referred to as crossbred (CR), were injected between 60 and 100 kg live weight with 6 mg/d of porcine somatotropin (pST) and compared to similar numbers of control females receiving the vehicle only. Average daily gain increased similarly in the three genotypes (125 g/d). Feed conversion ratio tended to decrease to a higher extent in MS (-2.0 kg of feed/kg of gain) than in the other two genotypes (-1.1 and -.9 kg of feed/kg of gain for CR and PI, respectively). A significant genotype x treatment interaction was also observed for backfat thickness (BF) and fat, muscle, and bone development. Effects of pST in PI, CR, and MS pigs were, respectively, -6.2, -9.6, and -16.1 mm for BF and 3.0, 6.8, and 11.8% carcass muscle. The influence of pST on physical measurements of meat quality was rather low, although desirable effects (P less than .05) were obtained on the reflectance and water-holding capacity of PI and CR. Intramuscular fat content was reduced by approximately 1% in MS and CR but not in PI. The metatarsals of pST-treated animals had a higher water content (except in PI), a lower mineralization, and a lower breaking strength (except in MS). The existence of breed variations in the response to pST might result in changes of the relative merit of crossbreeding schemes.

Cryogenic chilling of pork carcasses: Effects on muscle quality, bacterial populations and palatability

Two experiments were conducted to determine the effects of cryogenic chilling on the carcass shrinkage, meat quality, bacterial condition and palatibility of pork. In experiment I, pork sides were chilled at 1°C ( n = 20), or immersed in liquid nitrogen (LN) for 1 or 3 min prior to placement in a 1°C cooler. Muscle temperature in the loin was significantly lower at 2 and 6 h post mortem in treated compared to control sides, and loin muscle pH was higher ( P < 0·05) at 6 h post mortem in sides immersed for 3 min in LN. Carcass side shrinkage was reduced from 29·3 g kg −1 in control sides to 20·9 and 13·5 g kg −1 in sides dipped in LN for 1 and 3 min. Chilling treatment had no significant effect on the survival of mesophilic bacteria on carcass sides, on meat colour, drip loss, protein solubility or sarcomere length, but sides dipped for 1 min in LN has a higher muscle shear value than control sides. In experiment II, carcass sides from halothane positive (H+) and negative (H−) pigs were conventionally chilled ( n = 49), immersed in LN for 3 min ( n = 23), or electrically stimulated and chilled in LN for 3 min ( n = 26). Similar results for temperature, pH, colour, protein solubility and drip loss in loin muscle were found to those in experiment I. Laboratory taste panel results showed that chilling treatment had no effect on palatability. Genotype produced meaningful differences in most palatability attributes with H+ pigs having less tender, less juicy and less desirable flavour than pork from H− pigs. Laboratory studies with inoculated fresh muscle slices showed that a 3 min immersion in LN resulted in a 10-fold reduction in the aerobic spoilage pseudomonads, but effects upon other spoilage bacteria and potential human pathogens were less pronounced. It was concluded that cryogenic chilling using LN reduced carcass shrinkage during cooling, but had no consistent effects on meat quality, palatability or bacterial numbers on the carcass. In contrast, genotype had a significant effect on most pork quality and palatability attributes.

Prediction of Pork and Lamb Meat Quality Characteristics

ABSTRACTA two‐factor central composite rotatable design and corresponding response surface analysis were successfully applied to data from pork and lamb loin roasts, using cooking temperature and endpoint temperature as the two independent variables. Heating rate (°C/min), evaporation loss, cooking time, total moisture, and chromaticity coordinate (z) were found to be significantly affected (p ≤ 0.10) by different combinations of cooking temperatures and endpoint temperatures in pork and lamb. Additional significant variables for pork were total nitrogen, remaining protein fraction and sensory panel juiciness; and for lamb, heating rate (°C/g), drip loss, total cooking loss, expressible moisture index, total nitrogen, chromaticity coordinate (×), saturation index, and sensory panel doneness and color. Response surfaces were useful in evaluating results.

Use of specialized breeds for increase of pork meat quality

Aim. Matching ability to study for reproductive, fattening and meat qualities of pigs and to identify the most effective combinations of genotypes national and foreign selection. Methods. Studies conducted in conditions of industrial technology of LLB "Mayak-Agro" Cherkassy region. Groups formed by from counterpart’s methods. Assessment fattening and meat quality was carried out by conventional methods (Polivoda A., 1977). The chemical composition and physical properties of meat were determined by conventional methods in condition of biotechnology laboratories Cherkassy National University. B. Khmelnitsky. Results. The highest quantity offspring obtained by crossing hybrids with boars red white girdle (RWG) and pietrain (P) (11.6–11.8 piglets), with big fetus – when two breed crossed Ukrainian large white breed (ULW) sows of landrace (L) boars and sows of crossbred boars two bread from (P) (1.8 kg, P&gt;0.99). By weight of one head at weaning the best results are obtained by crossing two breeds ewes from boars (RWG) and (P) – 18.1–17.8 kg (P &gt; 0.999). Maximum saving values obtained when combined hybrids (ULW x L) with boars breed Duroc Ukrainian selection “Steppes” (DUSS) – 94.8 %. Conclusions. To improve the meat quality of pork, the best option is a combination of two breeds pig breeds (ULW x L) of boars (P) and (RWG).&#x0D; Keywords: hybridization, a specialized type, industrial crossing, heterosis, muscle area.