Characteristics of psychrotrophic microflora of bulk-collected raw milk from the Santa Fe area (Argentina)
1990
Reinheimer, J.A. | Demkow, M.R. | Clabrese, L.A. (Universidad Nacional Del Litoral, Santa Fe (Argentina). Facultad de Ingenieria Quimica)
In 223 samples examined, high levels of psychrotrophic contamination were found (mean 10 power 9 cfu per mL), with a high incidence of Pseudomonas spp. (51 percent of the strains isolated). A significant proportion of the psychrotrophic bacteria was found to be proteolytic and lipolytic. The proteases were highly stable at 40, 63, 100 and 140 deg. C, but their activity was partly lost when heated at 55 deg. C. When milk was pre-cultured with some psychrotrophic strains, the acidification rate of lactic cultures was, in most cases, stimulated; this was related to the degree of proteolysis.
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