Valoración tecnológica de lactobacilos de origen NSLAB para su uso como adjuntos en quesería.

BRIGGILER-MARCÓ, M.; QUIBERONI, A.; MILESI, M.; VINDEROLA, C.G.; HYNES, E.

Tucumán

Simposio; II Simposio Internacional de Bacterias Lácticas; 2006

Cerela

  Non starter lactic acid bacteria (NSLAB) are the only uncontrolled factor in today’s industrial cheesemaking and may be the cause of quality inconsistencies and defects in cheeses. In this context, adjunct cultures of selected lactobacilli from NSLAB origin appear as the best alternative to indirectly control cheese biota. The objective of the present work was to study the technological properties of Lactobacillus strains isolated from cheese by in vitro and in situ assays. Milk acidification kinetics, proteolytic and acidifying activities were assessed, and peptide mapping of TCA 8% soluble fraction was performed by liquid chromatography. In addition, the resistance to salts (NaCl and KCl) and phage attack was investigated. Four strains were selected for testing as adjunct cultures in cheesemaking experiments at pilot plant scale.  In in vitro assays, most strains acidified milk slowly and showed a weak proteolytic activity. Fast strains decreased milk pH up to 4.5 in 8 h, and continued acidification up to 3.5 in 12 h or more.  This group consisted mostly of L. plantarum and L. rhamnosus strains. Approximately one third of the slow strains, which comprised mainly L. casei, L. fermentum and L. curvatus, were capable to grow when milk was supplemented with glucose or casein hidrolysate. Peptide maps were similar to those of lactic acid bacteria considered moderately proteolytic.  All the strains showed salt resistance and were not sensitive to specific phage attack.  The Lactobacillus strains selected as adjunct cultures in cheesemaking experiments reached 108 CFU g-1 in soft cheeses at 7 days of ripening, whereas they attempted 109 UFC g-1 in semi-hard cheeses after 15 days of ripening. In both cheese varieties, the adjunct culture population remained at high numbers during all ripening, in some cases overcoming or equaling primary starter. Proximate composition of cheeses with and without added lactobacilli did not differ, however, some of the tested strains continued acidifying during ripening, which was mainly noticed in soft cheeses. Overall, the lactobacilli studied in the present work showed appropriate technological characteristics for their use as adjunct cultures in cheese, especially those with low acidifying activity. Finally, moderate proteolytic activity detected in fast strains may favorably contribute to secondary proteolysis during cheese ripening.