EFFECT OF MUSCLE-TYPE AND FOOD-DEPRIVATION FOR 24 HOURS ON THE COMPOSITION OF THE LIPID FRACTION IN MUSCLES OF LARGE WHITE-PIGS

The present study was designed to examine the lipid composition of a p redominantly glycolytic (M. longissimus lumborum, LL) and a predominan tly oxidative (M. semispinalis capitis, SC) muscle sampled at slaughte r from Large White pigs fed or deprived of food for 24 h. The intramus cular lipid content was almost four-fold higher in the red SC than in the white LL. When expressed on a muscle tissue basis, the results ind icated that the LL had significantly lower amount of tri-, di- and mon oglycerides, free fatty acids, cholesterol and phospholipids than the SC. In both muscles, phosphatidylcholine represented the major constit uent of the phospholipid fraction. The difference in phospholipid cont ent between the LL and the SC was significant only for cardiolipin, ph osphatidylethanolamine and phosphatidylinositol. When expressed on tot al lipid basis, the results showed that the SC contained significantly lower amount of phospholipids and higher amount of triglycerides than the LL, thus suggesting that the influence of muscle type on the cont ent of intramuscular lipid was primarily due to a difference in the am ount of triglycerides. Food deprivation for 24 h resulted in a signifi cantly higher content of free fatty acids, as expressed on a muscle ti ssue basis, in both muscles. Relative to total lipid, food deprivation resulted in increased levels of free fatty acids and monoglycerides o nly in the LL. These results suggest that food deprivation for 24 h in duced lipolysis in muscle, as evidenced by a modification in the relat ive composition of the neutral lipid fraction, but that this effect wa s muscle-dependent.