Intramuscular Fat Groups Research Articles

Perilipin 1 and perilipin 2 protein localization and gene expression study in skeletal muscles of European cross-breed pigs with different intramuscular fat contents

This study investigated the lipid droplet coat proteins perilipin 1 (PLIN1) and perilipin 2 (PLIN2) localization in pig skeletal muscle and their relationship with intramuscular fat (IMF) content. PLIN1 and PLIN2 proteins were immunostained in semimembranosus muscle cross-sections from two groups of samples divergent for IMF and the gene expression was quantified. PLIN1 localized in the periphery of intramuscular adipocytes, whereas PLIN2 localized within myofibers with high lipid content. The high IMF group showed higher total cross-sectional area of PLIN1-stained adipocytes compared with the low IMF group ( P < 0.05), while the cross-sectional area and percentage of PLIN2-positive myofibers did not differ between IMF-divergent groups. This suggested that IMF content is mainly determined by extra-myocellular lipids. At mRNA level, PLIN2 expression was higher in high IMF muscles ( P < 0.05). The results indicate for the first time that in pig muscle PLIN1 and PLIN2 proteins are localized in correspondence with extra and intra-myocellular lipids, respectively.

Effect of protein level in commercial diets on pork meat quality

This study assessed the effect of protein level on meat quality, intramuscular and subcutaneous fat, instrumental texture and sensory attributes on Longissimus dorsi in pork. Animals were fed two experimental diets that produced two animal groups with different percentages of intramuscular fat (IMF) (1.76 vs. 2.63). There were no significant differences in meat quality or texture profile analysis parameters between IMF groups. The percentage of saturated fatty acids was also similar, but the percentage of monounsaturated was significantly higher in the group with higher IMF and the percentage of polyunsaturated fatty acids was higher in the group with lower IMF. IMF groups had little effect on the fatty acid composition of subcutaneous fat. Warner-Bratzler shear force (WBSF) values were significantly higher in the group with lower IMF, whereas tenderness was higher in the group with higher IMF. Finally, WBSF appeared to be a good predictor of the tenderness for grill-cooked pork.

Influence of intramuscular fat content on lipid composition, sensory qualities and consumer acceptability of cured cooked ham.

The present study is part of a project which aims to examine the influence of intramuscular fat (IMF) content on the sensory attributes and consumer acceptability of pork. An experiment was conducted to evaluate the influence of IMF level in muscle semimembranosus (SM) on the composition of its lipid fraction and on the sensory qualities and consumer acceptability of cured cooked hams. Thirty-two carcasses were selected 24 h after slaughter from 125 Duroc × Landrace castrated male pigs showing large variability in SM muscle IMF content and were assigned to four IMF groups: ≤2%, 2-3%, 3-4% and >4%. Cured cooked ham slices were evaluated by a trained expert panel of 12 members and by a group of 56 consumers. Results from lipid analyses indicate that (i) an increase in IMF content was almost entirely reflected by an increase in the triglyceride content of the muscle and (ii) higher IMF levels were associated with higher free fatty acid and monoglyceride and lower cholesterol levels. The sensory evaluation of marbling significantly increased with IMF level, whereas other sensory qualities were unaffected. High IMF levels significantly depreciated the consumer perception of fat, aspect, taste and smell of ham slices. Overall, slices with the highest IMF levels got the least favourable rating by consumers. The present study indicates that increased IMF levels in muscle semimembranosus do not have significant effects on the sensory attributes of cured cooked hams, apart from the perception of marbling. However, high IMF levels have detrimental effects on the acceptability by consumers. © 2000 Society of Chemical Industry.

Influence of intramuscular fat content on the quality of pig meat — 2. Consumer acceptability of m. longissimus lumborum

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.