TIME-RELATED CHANGES IN NITROGEN FRACTIONS AND FREE AMINO-ACIDS OF LEAN TISSUE OF FRENCH DRY-CURED HAM

The 80 hams of 40 pig carcasses from one slaughter batch were taken on the day after slaughter. The 40 left hams were dry-cured Groups of 10 hams were taken for analysis at 74 days (end of rest), 81 days (end o f heating), 179 days (mid-seasoning) and 273 days (end of seasoning) a fter the beginning of processing. A slice of about 150 g was taken in the middle of the Biceps femoris and used for analysis of nitrogen fra ctions and free amino acids by HPLC Levels of insoluble nitrogen compo unds did not vary significantly, while levels of soluble protein nitro gen decreased strongly from 26 to 16% of total nitrogen, with the fast est decrease observed between days 179 and 273. Levels of non-protein nitrogen increased regularly during the processing from 12 to 23% of t otal nitrogen. Nitrogen of free amino acids ranged from 3-6% in fresh muscle to 16.6% of total nitrogen at day 179, then decreased to 4-4% o f the total nitrogen at the end of the processing. The HPLC method all owed the identification of 29 compounds, among which 27 were amino aci ds and 2 were dipeptides. The average levels of free amino acids of no n-protein origin tended to decrease before day 74, then to increase un til day 179 and to decrease again. The levels of compounds of protein origin increased or tended to increase from the beginning until day 17 9, then decreased.