QUALITATIVE ASSESSMENT IN SALTED RED MULLET (MULLUS SURMULETUS, L. 1758)

Abstract

In this study, microbiological and chemical properties of red mullet (Mullus surmuletus, L. 1758), treated by dry salting and stored for 120 days at 4 ± 1ºC, were investigated. Samples were divided in two lots and put in glass (G) and in glazed crock (C) jars. Microbial load was low at 0 day and during a 120 day period; aerobic mesophilic, psychrophilic and alophilic/alotollerant bacteria counts increased during the first 7 days in both samples; then, a decrease occurred during the whole ripening period; total coliforms and yeast-mould counts were always low. Samples microbial load at 0 day showed a good quality of not processed fishes. pH value at 0 day was 6.65; then it decreased during ripening. Total volatile basic nitrogen and trimethylamine nitrogen values, at 0 day, were low (6,982 mg/100 g; 2,618 mg/100 g, respectively); during ripening the amounts slightly increased in both samples. Overall, a good samples stability during the whole ripening period was considered. Several volatile compounds were identified in all Mullus surmuletus specimens by SPME-GC-MS; in all the samples hexanal, heptanal and (Z)-4-heptanal, typical aroma compounds in salted fish, prevailed. Statistically significant (P< 0,05) differences between G and C and control sample (0 day) during ripening of salted mullet for chemical aspects were observed. The results, altogether, showed that dry salting process is useful to give stability to Mullus surmuletus. The jar material improved the development of typical aroma compounds and it could be proposed for a niche product made for use in a small and specialized, but profitable, market. The glass could be used for industrial production since it provides uniformity for aroma during the maturation.