Evaluation of proteolytic activity of micro-organisms isolated from dry cured ham

Abstract

IO . 1998. In order to determine the possible contribution of micro-organisms to the ripening of meat products, 48 cocci, 18 moulds and 20 yeasts isolated from dry-cured Iberian ham were evaluated for proteolytic activity. Two specific methods were used: the ability to hydrolyse myosin in broth and, for those strains showing high activities, hydrolysis on both myofibrillar and sarcoplasmic proteins on pork slices. Moulds and cocci showed the highest proteolytic activity for myosin in broth. Both myofibrillar and sarcoplasmic proteins were recovered at lower rates from inoculated than from sterile incubated pork. The deepest changes in myofibrillar and sarcoplasmic proteins were originated by one strain each of Penicillium chrysogenum and Staphylococcus xylosus, respectively. Only small changes were observed in the concentrations of free amino acids from inoculated pork slices, except for the samples with P. chrysogenum, where there were increases in all free amino acids. Thus, P. chrysogenum makes a significant contribution to proteolysis during the ripening of dry-cured meat products.

Determination of lipolytic and proteolytic activities of mycoflora isolated from dry-cured teruel ham

“…Finally, it should be noted that the total of strains tested showed greater proteolytic activity against pork myosin than the control strain P. cammemberti (CECT 2267). In this sense, new bands of 92 and 80 kDa coming from myofibrillar proteins have already been related to microbial growth on pork (Rodríguez et al 1998;Martín et al 2002). In the same way, Toldrá (1998) related a progressive hydrolysis of myosin and troponins taking place in all types of dry-cured ham gives rise to fragments mainly with 150, 95 and 16 kDa.…”

“…It should be noted that 84.61 % of the strains that showed proteolytic activity belonged to the genus Penicillium (Table 1). In this sense, proteolytic activity of the Penicillium genus has been reported by several researches (Núñez 1995;Rodríguez et al 1998;Toledano et al 2011;). As mentioned above, this fact could be one of the reasons why Penicillium fungi have been used historically in food industry as starter in meat fermented products (Leistner 1986;Mintzlaff and Christ 1973).…”

“…In contrast, the P. commune strain KC009806 showed a high proteolityc activity (halo size>10 mm). In this sense, the ability of P. commune to produce proteolytic reactions in meat products has been reported in several studies (Núñez et al 1996;Rodríguez et al 1998).…”

“…Strains that showed a halo size higher than 5 mm on PDA-Casein medium were also tested against pork myosin (myosin M-0273, Sigma, St. Louis, MO) according the method described by Rodríguez et al (1998). For control purposes, an appropriate molecular weight marker (Marker M3788, Sigma, St. Louis, MO) was added to the myosin solution and incubated under the same conditions.…”

“…Binzel (1980) reported that Eurotium and Penicillium were able to hydrolyse myoglobin. Strains belonging to these genera, isolated in Iberian ham, have also demonstrated considerable activity when exposed to myosin (Rodríguez et al 1998). …”