Influence of intramuscular fat content on the quality of pig meat — 1. Composition of the lipid fraction and sensory characteristics of m. longissimus lumborum

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.