Growth/no growth interface of Brochothrix thermosphacta as a function of pH and water activity

A growth/no growth boundary model based on interpolated probabilities is pr esented in this paper. The boundary is defined as the loci where the probab ility of growth for a sample is equal to its chance of no growth, P(growth) = P(no growth). Brochothrix thermosphacta was used as a test micro-organis m to collect data near the boundary of growth/no growth, in a pH/NaCl grid. Results showed a dramatic change in the probability of growth at the bound ary with minor changes of pH or NaCl, and that the location of the boundary was affected by the inoculum level A quadratic polynomial was used to desc ribe the boundary of the growth region (interpolated P = 0.5). The importan ce of growth/no growth boundary models as limits for the application of kin etic models is discussed (C) 2000 Academic Press.