Application of a mathematical model to describe the behaviour of the Lactobacillus spp. during the ripening of a Spanish dry fermented sausage (Chorizo)

The evolution of Lactobacillus spp. during the curing process of dry fermented sausage (Chorizo), has been studied under natural climatic conditions and in a controlled drying chamber, with regulated temperature and relative humidity. In order to fully understand the development of the microorganisms in each of these two cases, it applied a mathematical model based on a modified Gompertz equation. The proposed mathematical function is easy to use and statistically appropriate. Furthermore, it allows the distinction to be made between the four phases which characterise the behaviour of these microorganims during the curing of the sausage (a) latency from an initial threshold level; (b) exponential growth; (c) stationary state; (d) depletion to a residual level. The mathematical analysis of this function has highlighted certain differences in the behaviour of the microbial flora depending on the technological conditions to which the drying of the sausages is subjected. Under the climatically controlled conditions of the drying process, a better development of the Lactobacillus spp. is observed, but conversely the final stage of the exponential growth is brought forward, the length of the stationary phase is shortened and is reached before the end of the drying period, at which point the marginal decline of the microorganisms becomes ever more reduced.