HYNES Erica Rut
Nonstarter Lactobacillus Strains as Adjunct Cultures for Cheese Making: In Vitro Characterization and Performance in Two Model Cheeses
MARIÁNGELES BRIGGILER MARCÓ; MARÍA LUJÁN CAPRA; ANDREA QUIBERONI; GABRIEL VINDEROLA; JORGE REINHEIMER; ERICA HYNES
JOURNAL OF DAIRY SCIENCE
ADSA (American Dairy Science Association)
Lugar: Savoy; Año: 2007 vol. 90 p. 4532 - 4532
Nonstarter lactic acid bacteria (NSLAB) are the main uncontrolled factor in todays industrial cheese making 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 trichloroacetic acid 8% soluble fraction of milk cultures was performed by liquid chromatography. In addition, the tolerance to salts (NaCl and KCl) and the phage-resistance were investigated. Four strains were selected for testing as adjunct cultures in cheese making experiments at pilot plant scale. In in vitro assays, most strains acidified milk slowly and showed weak to moderate proteolytic activity. Fast strains decreased milk pH to 4.5 in 8 h, and continued acidification to 3.5 in 12 h or more. This group consisted mostly of Lactobacillus 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 and casein hydrolysate. Peptide maps were similar to those of lactic acid bacteria considered to have a moderate proteolytic activity. Most strains showed salt tolerance and resistance to specific phages. The Lactobacillus strains selected as adjunct cultures for cheese making experiments reached 108 cfu/g in soft cheeses at 7 days of ripening, whereas they reached 109 cfu/g in semihard cheeses after 15 days of ripening. In both cheese varieties, the adjunct culture population remained at high counts during all ripening, in some cases overcoming or equaling primary starter. Overall, 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 and impacted overall quality of the products. The lactobacilli strains with low acidifying activity showed appropriate technological characteristics for their use as adjunct cultures in both soft and semihard cheeses.