Application of a mathematical model for the inhibition of Enterobacteriaceae and clostridia during a sausage curing process

The application of a mathematical model capable of providing expressions suitable for analysis of the population changes of Enterobacteriaceae and clostridia during the curing process of dry fermented sausage is proposed to facilitate better control of the safety of the product. The mathematical model provides curing times that are crucial for control of the safety of the product: the beginning of the exponential phase of inhibition, the time during which the rate of inhibition is at a maximum, and the phase in which the rate of decline of the population of microorganisms decreases until they virtually disappear from the sausage. For Enterobacteriaceae, growth inhibition and eventual disappearance are dependent on conditions during sausage drying; for clostridia the means of drying is not significant. Under programmed controlled drying conditions, the maximum speed of inhibition and the disappearance of undesirable microorganisms are reached sooner than under natural climatic drying conditions. A regression equation has been established that relates the cell number of Enterobacteriaceae to pH and a(w), values, and the cell number of Lactobacillaceae, whose metabolic activities give rise to lactic and acetic acids. The significance of the drying conditions may verify the values reached by all these parameters during curing.