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Growth of lactic acid bacteria (LAB) and lactobacilli was studied in Cheddar cheeses supplemented with live and heat-shocked Lactobacillus casei subsp. cosei L2A and with Neutrase@ to accelerate maturation. Bacterial counts of treated cheeses rapidly reached maximal values within 1 wk, whereas the control cheese reached comparable values only after 2 mo. Addition of 1.0% heat-shocked lactobacilli led to an excellent quality Cheddar cheese with a 50% increase in flavor development, as determined by sensory evaluation, compared to control cheese. Addition of Neutrase (1 x 1O-5 AU/g cheese) permitted a gain of an additional 10% while addition of higher concentrations (2 and 4x 10e5 AU/g cheese) resulted in undesirable bitterness.

The addition of live and heat-shocked Lactobacillus casei-casei L2A and Neutrase" was tested for its ability to accelerate the maturation of Cheddar cheese. An evaluation of physicochemical and rheological properties showed that cheese pH was decreased by bacterial and enzymatic additives, while fracturability and cohesiveness were influenced principally by Neutrase. The integrated process recommended is composed of three parts: first, the addition of live L. casei-casei L2A to control the undesirable microflora, second, heat-shocked cells of the same species at a concentration of l.O%, and third, Neutrase at a concentration not higher than 1.0 x 1O-5 AU/g of cheese. This process led to a good-quality sharp Cheddar cheese with 60% increase in flavor intensity compared to control cheese.

The aim of this study was to establish adequate conditions for heatshocking cells of lactobacilli, to sufficiently suppress lactic acid production without damaging the proteolytic enzyme system important for cheese maturation. Three temperatures, 65, 67 and 70°C were tested, for 22 sec. The best combination for maximum retardation of lactic &id production and minimum damage to the proteolytic system was obtained bv treating cells at 67°C for 22 sec. Followine such treatment, lactic acid pkduction was retarded by 24 hr, wh3e the proteolytic enzyme system remained scarcely unchanged.

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