15A-6 |
Identification of heat-resistant lactic acid bacteria isolated from Mexican sausages |
M. D. L. PÉREZ-CHABELA, I. Guerrero-Legarreta, E. Ponce-Alquicira, V. Chavarín, M. E. Cocoletzi, J. Ugalde, S. Vazquez, and S. Martinez. Dept. de Biotecnología, Univ. Autónoma Metropolitana-Iztapalapa, Av. Michoacán y la Purísima s/n Col. Vicentina, México, DF, 09340, Mexico Lactic acid bacteria have been reported as a means of surface decontamination of meat cuts. It is also well known that fermented sausages present an extended shelf life mainly due the presence of competitive lactic strains. These cultures impart pleasant flavor and aroma and inhibit the growth of pathogens and spoilage microorganisms by several mechanisms. In some emulsified sausages, such as wieners, reduction of undesirable microflora due to contamination of raw materials can be achieved by using selected lactic strains. The objective of this work was to isolate and characterize heat-resistant lactic acid bacteria potentially able to be used as bioprotective strains in emulsified meat products undergoing thermal treatment. Twenty-five lactic strains were isolated from Mexican sausages. The strains were grown on APT broth where acid production (expressed as total titrable acidity and pH) was evaluated. The strains were also subjected to heating in a water bath at 40, 50, 60 and 70oC during 5, 10 and 15 minutes. Biochemical tests were used as preliminary identification: Gram stain, catalase and decarboxylase activity, growth in anaerobic conditions, salt resistance, fermentation of various sugars and motility. The results showed that all the studied strains were very efficient acid producers. Seventeen strains survived heat treatment at 70oC for 15 minutes. From the biochemical tests, it was concluded that 18 strains presumable belong to family Lactobacillaceae. In this respect, however, it is necessary to carry out phenotypical identification of these strains. It is also important to study possible production of other metabolites that alter sausage quality. Use of bioprotective strains ensures microbial quality of sausages, even in conditions of temperature abuse or failure. When these strains are used in heat-treated sausages such as wieners, heat-resistance of the culture is fundamental as well as lack of metabolite production, potentially altering sausage quality
Session 15A, Biotechnology
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