Composition and proteolytic and lipolytic enzyme activities in muscle Longissimus dorsi from Iberian pigs and industrial genotype pigs

Abstract

In this study, composition and fatty acid profiles of intramuscular lipid fractions, proteolytic and lipolytic muscle enzyme activities in muscle Longissimus dorsi have been determined in three lines of Iberian pigs (“ Lampi ñ o”, “ Retinto” and “ Torbiscal”) reared under the free-range system and slaughtered at 90kg live weight and industrial genotype pigs (IGP) (Large White-Landrace × Large White) reared intensively. Intramuscular fat content was significantly higher ( p<0.05) in Iberian pig lines (IPL) than in IGP. Neutral lipids of IPL showed higher ( p<0.05) percentages of palmitic, oleic, total saturated fatty acids and monounsaturated fatty acids and lower ( p<0.05) percentages of polyunsaturated acids and linoleic acid in neutral and polar lipids than IGP. No statistical differences were found in cathepsin B or B + L or phospholipase residual activities between IPL and IGP, while cathepsin H residual activity was significantly ( p>0.05) higher in IGP than in IPL. The ratio cathepsin B + L/B was significantly lower ( p<0.05) in IGP and “ Lampi ñ o” line than in “ Retinto” and “ Torbiscal” lines. Acid lipase residual activity showed a significantly ( p<0.05) higher activity in IPL than in IGP. The activity of neutral lipase was significantly higher ( p<0.05) in “ Torbiscal” line and lower in the “ Lampi ñ o” line while the “ Retinto” line and IGP showed intermediate activities. Acid esterase activity was higher ( p<0.05) in “ Retinto” and“ Torbiscal” lines than in IGP and the “ Lampi ñ o” line. The different enzyme patterns in fresh meat may explain the wide proteolysis and lipolysis variations usually observed in the processing of dry-cured ham.