title: Activities of pork muscle proteases in model cured meat systems.
abstract: The effect of curing agents (salt, nitrate, ascorbic acid and glucose) and processing parameters (pH, water activity and drying and cooking temperatures) on pork muscle cathepsins B, D, H and L as well as leucyl, arginyl and tyrosyl hydrolysing activities is reported. Salt (60 g/l) showed a powerful inhibitory effect, especially on cathepsin D and aminopeptidase activities where less than 13% of the original activity was recovered. Cathepsin H was also affected (38% of the original activity) while cathepsins B and B+L recovered 72.5 and 63.0%, respectively. Nitrate (0.2-0.25 g/l) and ascorbic acid (0.2-0.4 g/l) did not significantly affect the enzyme activities. On the other hand, 0.5-2 g/l of glucose activated both cathepsins B and D with an increase of 39.5 and 28.5% and also leucyl and arginyl hydrolysing activities which were 75.0 and 24.0%, respectively. No aminopeptidase activity was detected when assayed in 100 mM sodium citrate buffer, pH 5.1. Cathepsin H was also very affected at that pH and only 12.0% of activity was recovered. A decrease in water activity, especially below 0.84, also affected the enzyme activities which were found below 50%. Temperatures in the usual range of the drying process (22 and 30 degrees C) gave substantial enzyme activities (around 40-50 and 80%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Instituto de Agroquímica y Tecnología de Alimentos (CSIC) Valencia, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Toldrá
authors.forename: E
authors.initials: E
authors.lastname: Rico
authors.forename: J
authors.initials: J
authors.lastname: Flores
mesh_terms: D000626:Aminopeptidases / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D002403:Cathepsins / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D005285:Fermentation; D005947:Glucose / Q000494:pharmacology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008461:Meat Products; D009132:Muscles / Q000187:drug effects / Q000201:enzymology*; D009566:Nitrates / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D013552:Swine; D014867:Water
chemical_list: D009566:Nitrates; D014867:Water; D012965:Sodium Chloride; D002403:Cathepsins; D010450:Endopeptidases; D000626:Aminopeptidases; D005947:Glucose; D001205:Ascorbic Acid