Abstract
The contribution of Streptococcus thermophilus to histamine formation during cheese ripening was evaluated. Cheeses were produced using, as starter cultures, histamine-producing or non-producing S. thermophilus strains (PRI60 and PRI40, respectively), in combination with a decarboxylase-negative Lactobacillus helveticus strain. Cheeses inoculated with the strain PRI40 and with cell-free extracts of PRI60 added were also produced. The different combinations of starter cultures were responsible for different proteolytic patterns as demonstrated by the behaviour of water-soluble, trichloroacetic soluble, and phosphotungstic acid soluble nitrogen. A single histaminogenic strain, present during fermentation and ripening, also in the form of a cell lysate, produced histamine up to 180 mg kg−1 in cheese. Histamine was found at a higher level in cheeses manufactured with PRI60 starter, but was also detected in cheese containing the cell-free HdcA enzyme. The problem of histamine formation by S. thermophilus in artisanal cheeses must not be overlooked, especially during typical production practices.
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