SUBCUTANEOUS ADIPOSE TISSUE LIPOLYSIS IN THE PROCESSING OF DRY-CURED HAM

ABSTRACT The activities of subcutaneous adipose tissue lipases and esterases were assayed at different stages (0 to 15 months) in the processing of dry-cured ham. The formation of free fatty acids during the process was also determined. Maximal generation of free fatty acids occurred during the first 10 months. Simultaneously, the triglyceride content decreased while the diglycerides increased during the aging period. Neutral and basic lipases showed maximal activity at the beginning of the process but only neutral lipase remained as the main enzyme responsible for the reported lipolysis during the drying ripening stages. Adipose tissue esterases showed excellent stability but the generation of volatile free fatty acids was negligible, suggesting a minor role of these enzymes.     

Biogenic Polyamines Affect Activity of Aminopeptidase B and Alanyl Aminopeptidase from Porcine Skeletal Muscle

The effect of biogenic polyamines (agmatine, cadaverine, putrescine, spermidine, and spermine) on the activity of pork muscle aminopeptidase and alanyl aminopeptidase was investigated. Agmatine (5 mM) showed a powerful inhibitory effect for both enzymes (more than 50% inhibition). Cadaverine and less intensely putrescine showed similar inhibitory effects for both enzymes. All assayed polyamines inhibited activity of both aminopeptidases except spermine and spermidine which did not affect aminopeptidase B. Thus, one of these inhibitors could be used to avoid the interference of alanyl aminopeptidase when assaying aminopeptidase B in muscle extracts.     

Muscle and Adipose Tissue Aminopeptidase Activities in Raw and Dry-Cured Ham.

Free amino acids have been analyzed in biceps femoris muscle and adipose tissue from raw and dry-cured ham. A high increase was observed for all amino acids except glutamine and taurine. Major increases were in glutamic acid, arginine, alanine, valine, leucine, and lysine. A survey of five aminopeptidase activities of muscle and adipose tissue from raw and dry-cured ham was performed by using 7-amino-4-methylcoumarin derivatives of five amino acids (Leu, Arg, Ala, Tyr and pGlu) as substrates. Optimum activity was found at neutral pH and around 37°C, except the leucyl hydrolyzing activity which was 45°C. High recoveries of activity (25–75%) were obtained in the dry-cured ham. These enzymes might be responsible for free amino acids increasing during dry-curing.     

EFFECT OF CARNOSINE, ANSERINE AND OTHER ENDOGENOUS SKELETAL PEPTIDES ON THE ACTIVITY OF PORCINE MUSCLE ALANYL AND ARGINYL AMINOPEPTIDASES

The effect of endogenous dipeptides (carnosine and anserine) and peptidic fractions from meat extracts on aminopeptidase activity, alanyl and arginyl aminopeptidases purified from porcine skeletal muscle, was studied. Carnosine inhibited the activity of porcine arginyl aminopeptidase (RAP); the inhibition being stronger with the purified form of the enzyme than in the muscle extract. The RAP inhibition was competitive. One of the peptidic fractions isolated from meat extracts inhibited RAP activity But the degree of inhibition depended on the extent of purification. The major aminopeptidase present in muscle, alanyl aminopeptidase (AAP), was neither inhibited by natural dipeptides nor arty of the peptidic fractions. The study of meat inhibitory peptides provides a better understanding of the action of proteolytic enzymes during meat processing.