Proteolysis of anchovy sarcoplasmic proteins during lactic acid fermentation. Effect of sodium chloride

CAROLINA BELFIORE; SILVINA FADDA; GRACIELA VIGNOLO

San Migeul de Tucumán, Argentina

Simposio; III Simposio Internacional de Bacterias Lácticas.; 2009

CERELA-CONICET

Proteolysis of anchovy sarcoplasmic proteins during lactic acid fermentation. Effect of sodium chloride C. Belfiore, S. Fadda, G. Vignolo Centro de Referencia para Lactobacillus (CERELA). Chacabuco 145. 4000 San Miguel de Tucumán, Argentina. E-mail: cbelfiore@cerela.org.ar Anchovy (Engraulis anchovy), a pelagic species is usually salt-ripened during a slow process that takes 6-9 months to be completed. Ripening involves a series of complex biochemical processes transforming the raw material in a much appreciated gastronomical product with a pleasant texture, aroma and flavor. It is know that the ripening of salted anchovy take place via enzymatic pathways, the importance attributed to tissular enzymes versus microbial enzymes being controversial. The aim of the present work was to evaluate the ability of three strains of lactic acid bacteria (LAB) isolated from anchovies to degrade fish proteins during growth in an anchovy soluble extract with or without addition of NaCl. The assays were carried out in a sterile experimental muscle system obtained from macerated fresh anchovy containing 0 and 10% NaCl. The culture medium was independently inoculated with Lactobacillus sakei SACB704, Lactobacillus curvatus SACB03a and Leuconostoc mesenteroides SACB07 isolated from anchovies and the protein degradation as well as the amino acids content were determined by SDS-PAGE and OPA assay, respectively. A non-inoculated control medium was also included. In absence of NaCl, LAB showed a significant growth, from… to…. after 15 days with a good acidification ability (pH values decreased from 6.5 to 3.7); while when 10% NaCl where added on the muscle extract LAB strains remain viable until the end of fermentation time showing less pH variation (5.9 to 5.0-4.5). When the amino acid content was analyzed, an constant amino acid increase was observed in presence of LAB or in sterile condition, indicating the existence of a complex enzymatic activity becoming from digestive, muscular and bacterial (aminopeptidases) origin. The protein patterns resulting from the action of LAB strains analyzed by SDS-PAGE showed that the highest proteolytic profile was obtained when L. curvatus SACB03a was the responsible for this fermentation process without salt addition. The disappearance and/or decrease in intensity of protein bands from 66 to 14 kDa was observed already at 24 h. However when this strain grew in presence of NaCl no proteolytic changes were observed. In constrast, in such condition (10% NaCl), L. sakei SACB704 and Leuc. mesenteroides SACB07 evidenced relatively higher changes on the protein profile than L. curvatus SACB03a. These results indicate that both, endogenous enzymes and LAB participate on fish protein degradation which was inhibited by NaCl. This work constitutes an initial approach to elucidate fish protein degradation by autochthonous LAB, which may contribute to the release of peptide and amino acids with an impact in the flavour of final product.