The present study is part of a project which aimed to examine the influence of intramuscular fat (IMF) content on the sensory attributes and consumer acceptability of pork. Two experiments were ...conducted to evaluate the influence of IMF level on the composition of the lipid fraction and on the sensory qualities of muscle
longissimus lumborum (LL). Each of these experiments used 32 castrated male pigs selected after slaughter either from 125 Duroc×Landrace (Experiment 1) or 102 Tia Meslan×Landrace (Experiment 2) crossbred animals, and showing large variability in LL IMF content: from <1.5 to >3.5% in Experiment 1 and from 1.25 to 3.25% in Experiment 2. Results from lipid analyses indicate that in both experiments, an increase in IMF content is almost entirely reflected by an increase in the triglycerides content of the muscle. In Experiment 2, higher IMF content was associated with higher free fatty acids. Marbling score was significantly affected by IMF level in Experiment 1 but not in Experiment 2. In Experiment 1, a trend towards a favourable effect of high IMF levels on flavour (
p=0.09) and tenderness (
p=0.055) was observed. In experiment 2, increased IMF level was associated with significantly higher juiciness and flavour scores. The results from the present study indicate that the variability in IMF level of LL muscle was almost entirely due to the variability in triglyceride contents. Favourable effects of increased IMF levels on the sensory attributes of pork were demonstrated in both experiments using different types of animals, but the nature and the magnitude of these effects depended on the experiment considered.
The present study is part of a project which aimed to examine the influence of intramuscular fat (IMF) content on sensory attributes and consumer acceptability of pork. Two experiments were conducted ...to evaluate consumer acceptability of pork chops with varying IMF level in muscle
Longissimus lumborum (LL). Each experiment used 32 castrated male pigs selected after slaughter either from 125 Duroc × Landrace (Experiment 1) or 102 Tia Meslan × Landrace (Experiment 2) crossbred animals, and showing large variability in LL IMF content: from <1.5 to >3.5% in Experiment 1 and from 1.25 to 3.25% in Experiment 2. A group of 56 consumers evaluated various items on rib-eye (LL muscle trimmed of backfat) (Experiment 1) and on entire chops trimmed of backfat (Experiment 2). Data from Experiment 1 indicate that an increase in IMF level is associated with an increase in visual perception of fat and a corresponding decrease in the willingness to eat and purchase the meat, when expressed before tasting. The latter effect disappeared after the consumers had tasted the meat, probably due to a positive effect of increase IMF, up to 3.5%, on the perception of texture and taste. In Experiment 2, where entire chops were evaluated, the perception of visible fat was not affected by IMF level, probably due to the lack of variation in the level of intermuscular fat between the four IMF groups. The willingness to eat and purchase the meat were unaffected by IMF level, whereas the perception of texture and taste was enhanced with increased IMF levels up to 3.25%. The present data suggest that the acceptability of pork may be improved by increasing IMF level but: (1) this effect disappeared for IMF levels higher than 3.5%, which are associated with a high risk of meat rejection due to visible fat and (2) the positive effect of increased IMF probably holds true as long as it is not associated with an increase in the level of intermuscular fat.
The world of meat faces a permanent need for new methods of meat quality evaluation. Researchers want improved techniques to deepen their understanding of meat features. Expectations of consumers for ...meat quality grow constantly, which induces the necessity of quality control at the levels of slaughtering, meat cutting, and distribution. This article is focused on techniques intended to predict technological and sensory qualities from measurements carried out on fresh intact meat. pH has been measured for a long time, but its on-line determination still progresses through automation. In the laboratory, NMR provides new insights on WHC mechanisms. Image processing has considerably improved the assessment of meat appearance. Developments of techniques for prediction of toughness are in progress, either directly, through ultrasonic analysis or NIR reflectance, or indirectly, through determination of connective tissue content by fluorescence probes. Control of authenticity benefits from the last developments of molecular biology and analytical chemistry. However, implementation of methods for meat quality evaluation has been very limited in the industry. The reasons for that situation are analyzed. Among the techniques recently described, the most promising for large-scale meat quality evaluation are considered to be ultrasonic analysis, image processing and NIR spectroscopy.
A total of 383 barrows and gilts from a French Large White experimental herd were slaughtered at 100 kg BW. Samples of longissimus muscle were taken to categorize myofibers according to their ...contractile (I, IIA, and IIB) and metabolic (oxidative and nonoxidative) properties. Myofiber percentages, cross-sectional areas (CSA), and relative areas were measured. Growth rate, carcass composition, muscle chemical composition, metabolic enzyme activities, and meat quality traits were also measured to estimate phenotypic and genetic correlations between these traits and myofiber characteristics. Genetic parameters were estimated using a REML procedure applied to an individual animal model. Heritabilities of fiber traits were moderate to high (h2 = .20 to .59). Highest heritabilities were found for type I fiber percentage (h2 = 46 +/- 11), type IIBw fiber percentage (h2 = .58 +/- .11), and type I fiber cross-sectional area (h2 = .59 +/- .10). For a given fiber type, the relative area was phenotypically and genetically more closely related to the percentage than to the CSA. Phenotypic correlations between fiber type composition and other traits were low. Genetically, growth rate, carcass leanness, and loin eye area were positively related to fiber CSA. Intramuscular fat content was not related to fiber type composition (rg = -.05 to .06), whereas it was positively related to fiber CSA (rg = .68). Type IIBw fiber percentage was related to pH at 30 min (rg = -.46), pH at 24 h (rg = -.62), glycolytic potential (rg = .31), and lightness of color (rg = .55) of longissimus muscle
This study was designed to evaluate Duroc (DU) crossing for Carso dry-cured ham production. One hundred fifty-four pigs (81 females and 73 castrates) of four different genotypes, pure Landrace pigs ...(LAN), offspring of LAN females crossed with Large White (LW) males (LWxLAN), offspring of LAN females crossed with DU males (DUxLAN), and offspring of LWxLAN females crossed with DU males (DUxLWxLAN), were chosen in the weight range of 105 to 120 kg (112.7 +/- 0.4 kg). Raw material quality was evaluated for ham fatness (intra- and intermuscular and subcutaneous) and meat quality (pH, color, water-holding capacity) of longissimus dorsi, biceps femoris, and semimembranosus muscles. Ham weight losses were recorded at different stages of processing. The biceps femoris and semimembranosus muscles were analyzed for chemical composition before (lipid, moisture, total nitrogen, nonprotein nitrogen) and after (moisture, salt, total nitrogen, nonprotein nitrogen) processing. Chemical and sensory analyses were performed on 96 dry hams (12 castrates and 12 females per genotype). Biceps femoris and semimembranosus muscles were evaluated for color, saltiness, aroma, and texture. Pigs of the four genotypes had similar ham fatness as estimated by subcutaneous fat thickness. Duroc crosses exhibited higher intramuscular fat content, marbling, and intermuscular fat. Crossing with DU resulted in lower weight losses during ham processing. Castrates were fatter and had more intra- and intermuscular fat and lower ham processing weight losses than females. A strong negative relationship between ham fatness and ham processing losses was observed. Chemical and sensory traits of dry ham muscles were little affected by DU crossing. Lower salt content of biceps femoris was found in DU crosses. Dry hams from female pigs had higher total and nonprotein nitrogen, but drier, firmer texture and higher resistance to cutting force compared to dry hams from castrated pigs. Crossing with DU demonstrated some disadvantages (more intermuscular fat, more slice visible fat) and advantages (lower weight loss and salt intake) for the quality of dry-cured ham.
Pigs of similar genetic backgrounds and feeding regimes were slaughtered in two abattoirs, one carrying out dehairing by scalding and the other by singeing. One ham from each of 80 carcasses was ...retained. Sixteen fresh hams (8 from each dehairing technique) were used for analysis while 64 hams were processed into dry-cured ham. Sixteen hams (8 from each dehairing technique) were taken for analysis at end of salting (day 14), end of rest (day 78), mid-processing (day 127) and end of processing (day 251). During processing, the water content of all muscles decreased while the salt content increased. The salt concentration in muscle water tended to equalize in all muscles. The nitrogen content of desalted dry matter (i.e. dry muscle tissue) decreased in both
Biceps femoris and
Semimembranosus. The content of every free amino acid increased with time, except for taurine and glutamine. Electrophoresis of the low ionic strength-soluble fractions showed all protein bands decreased during processing. Electrophoresis of the myofibrillar fractions indicated changes in all bands except actin (42kDa). These changes were more marked in the
Semimembranosus than the
Biceps femoris in the earlier processing steps. Ultrastructural changes were more marked in
Semimembranosus than
Biceps femoris. Hardness and chewiness increased in both muscles during the first half of processing then returned to values close to the initial ones in
Semimembranosus but changed little in
Biceps femoris. The scalded hams lost more weight than the singed ones during processing. The salt content was higher in scalded hams. Water-soluble nitrogen and NPN were higher in singed hams at the end of processing. The scalded hams were saltier and pungent. They had more pronounced aromas of dry ham, rancidity and hazelnut, and less aroma of fresh meat. Their texture was drier and less mellow.
The role of the 20S proteasome proteolytic effects was revisited using an ultrastructural approach with the aim to explain some particular structural changes identified in type I muscles and in high ...pH meat. In both types of meat, major changes observed after ageing are an increase in the thickness of the Z-line followed by the appearance of an amorphous protein structure spreading out over the I-band. This was followed by a total degradation of this amorphous structure and of the Z-line. Partial transversal fragmentation of the myofibrils within the I-band can also be detected. The data reported clearly demonstrate that the 20S proteasome was able to mimic these sequential structural changes, a feature never obtained with either calpains or cathepsins. It is the first time that a direct implication of this complex in postmortem muscle is postulated.
The day after slaughter, six chops of Longissimus lumborum from each of 10 Large White pigs and six Piétrain pigs were packed individually under vacuum and kept at 3–4 °C in the dark. At 1, 5 and 9 ...days after slaughter, two chops were used for analysis of lipids, thiobarbituric acid reactive substances (TBARS), sarcoplasmic Ca2+ and sarcoplasm and mitochondria phospholipase A2 activity. Free fatty acid content was higher in Piétrains than in Large Whites and increased with keeping time. Total lipids of Large White pigs contained more saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) and less polyunsaturated fatty acid (PUFA). Large Whites had less dioleoyl-linoleyl-glycerol (OOL) and Palmitoyl-oleoyl-linoleyl-glycerol (POL) and more Palmitoyl-oleoyl-stearyl-glycerol (POS) than Piétrains. The percentages of SFA and MUFA decreased and the percentage of PUFA increased with time in FFA of Large White pigs. In Piétrains, similar changes were observed between days 1 and 5, but later the percentages of SFA increased and the percentage of PUFA decreased again. TBARS tended to increase with time particularly in Piétrains. Sarcoplasmic phospholipase A2 decreased between days 5 and 9 in both breeds. Sarcoplasmic calcium was markedly higher at day 1 in Piétrains than in Large Whites then the difference decreased. These breed differences in lipid composition differences and lipid changes during storage are considered too small to be of practical importance, for instance in influencing the choice of a breed for pork production.
L’amélioration de la compétitivité des entreprises d’abattage de porcs ne repose plus essentiellement sur l’abaissement de leurs coûts, mais plutôt sur leur capacité à élever la qualité de leurs ...produits. La marge de progrès disponible la plus importante réside dans la part des opérations qui concerne les animaux vivants. Accroître la maîtrise des qualités de la viande implique nécessairement de mieux comprendre la réaction des animaux aux facteurs d’agression rencontrés lors de l’abattage, et ses effets sur ces qualités. Les connaissances disponibles dans ce domaine n’expliquent qu’une partie des mécanismes en cause, et il reste nécessaire de les approfondir, en portant particulièrement l’attention sur les interactions entre facteurs zootechniques et technologiques. D’une façon générale, il faut respecter un délai de 20 à 24 heures entre le dernier repas et l’abattage, prendre toutes les dispositions nécessaires pour minimiser les facteurs d’agression, en particulier un aménagement des locaux tenant compte des particularités comportementales du porc, et veiller à l’application optimale de l’anesthésie, qu’elle soit électrique ou gazeuse. Parmi les opérations succédant à l’abattage, la réfrigération est celle qui est susceptible de l’impact le plus marqué sur la qualité.
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