Lipolysis and oxidation in subcutaneous adipose tissue during dry-cured ham processing

In southern countries where the consumers eat the adipose tissue of ham sli ces, adipose tissue contributes to the typical flavour of ham. The aim of t his study was to investigate the changes in lipids of subcutaneous adipose tissue during dry-cured ham processing. Lipid hydrolysis and oxidation were followed in the adipose tissue of 30 hams (by groups of six) at different stages of processing (green ham, 6, 12, 18 and 24 months). The results show ed that: (1) Adipose tissue of the green ham contained 89.7% triacylglycero ls, 5.6% water and low amounts of free fatty acids (FFA) (0.1%), diacyl- an d monoacylglycerols (traces). The main triacylglycerols were di-oleoyl-palm itoyl glycerol (POO) (36.6%), palmitoyl-stearoyl-oleoyl glycerol (PSO) (19. 9%) and palmitoyl-oleoyl-linoleoyl glycerol (POL) (8.0%). Free fatty acids had a higher proportion of polyunsaturated fatty acids than triacylglycerol s (17.7% vs 8.3%). (2) An intense lipolysis occurred during the first 6 mon ths and continued at a slow rate up to 24 months. The amount of triacylglyc erols decreased from 89.6 to 75.8% while FFA, diacyl- and monoacylglycerol amounts increased to reach 10.5, 4.5 and 1.3%, in the 24 month old hams, re spectively. A preferential hydrolysis of triacylglycerols POO, POL and OOL was observed. Free fatty acid composition showed a sharp decrease in linole ic and stearic acids and an increase in palmitic acid. The decrease in lino leic content during the process suggested that this fatty acid acid was oxi dised. Both lipolytic and oxidative changes in lipids of adipose tissue cou ld affect its sensory traits, particularly colour and taste. (C) 1998 Elsev ier Science Ltd. All rights reserved.