Growth and production of volatiles by Staphylococcus carnosus in dry sausages: nfluence of inoculation level and ripening time

Three sausage batches inoculated with normal inoculation level of Pediococcus pentosaceus (5 x 10(6) CFU/g) and with low, intermediate, and high inoculation levels of Staphylococcus carnosus (10(5), 5 x 10(6), 5 x 10(7) CFU/g, respectively) were produced. Cell counts and formation of volatiles were followed throughout a ripening period of three weeks. The staphylococci exhibited the fastest growth in sausages with a low inoculation level, whereas growth was only moderate in sausages with a high initial level. Analysis of volatiles showed that methyl-branched aldehydes and acids, phenylacetaldehyde, 2-methyl-l-butanol, dimethyldisulphide and dimethyltrisulphide were produced in higher amounts in sausages with a high inoculation level of S. carnosus, whercas a low inoculation level correlated with high amounts of diacetyl, ethanol and ethyl esters. The levels of most compounds increased over time, but the amount of diacetyl was negatively correlated to ripening time. A negative interaction effect between inoculation level and ripening time was observed for the amounts of methyl-branched aldehydes.