Assessment of Alternative Protocols for Enumeration of Lactic Acid Bacteria Added As Starter Cultures in Salami Production

Abstract

ResumoThe main starter cultures used for the production of fermented meat products are microorganisms from the group of lactic acid bacteria (LAB) and Staphylococcus coagulase negative. Monitoring the populations is essential for maintaining the quality and safety of these products. However, conventional methods for enumeration of starter cultures in foods have limitations, due to poor selectivity and handling. Considering the lack of scientific data demonstrating the relevance of using Petrifilm™ AC plates associated with selective culture media for LAB enumeration in fermented meat products, the present study aimed to assess alternative protocols for the enumeration of starter culture in salami. Fourteen reference strains and two mix of starter cultures were plated on six different protocols: 1) Petrifilm™ AC added to chlorophenol red incubated in aerobiosis and 2) in anaerobiosis 3) agar MRS added to chlorophenol red 4) MRS added to bromocresol purple 5) MRS pH 5.7 and 6) agar All Purpose Tween. Then, samples of salami were obtained and their starter cultures enumerated by plating using protocols 1, 2, 3 and 5. The analysis of variance showed no significant differences between the enumeration protocols, independent of the incubation time: 24, 48 and 72 h. Generally, the counts of pure cultures of microorganisms and reference starter cultures showed no significant differences considering the different incubation times (except for AS 308 and S. xylosus in MRS at pH 5.7). The results indicated a significant 153