Predictive microbiology and table olives

The table olive is probably one of the most important and most recognized fermented vegetable in the food industry. Basically, the elaboration of this food is constrained to Mediterranean countries, but there are also well established production regions in Australia, USA and South-America. Thus, table olive elaboration is widespread around the world and represents an important economic source for the producing countries. Microorganisms play an important role in the production of table olives. Diverse groups are involved through olive fermentation determining the quality and flavor of the final product, but Enterobacteriaceae, lactic acid bacteria and yeasts are the most relevant. As in other food fermentations, it is necessary to favor the growth of desirable microorganisms and inhibit pathogen and spoilage microorganisms. Specifically, the levels of microorganisms in table olive fermentation and packaging can be controlled by diverse factors such us temperature, pH, water activity or additives. Predictive microbiology is a multidisciplinary area (statistical, microbiology, chemistry, food technology, etc.) which is devoted to quantitatively studying the effects of environmental factors on microbial growth in foods. The response is evaluated objectively by means of mathematical models, which can be later used as a useful tool to predict microbial response under different combinations of the variables. In this review, the different steps for the successful development and implementation of a predictive model in the specific case of table olive matrices will be discussed. It includes planning and experimental design, collection and analysis of data, model development, and, finally, validation and maintenance of the model. The most important predictive models (probabilistic, polynomial, neural networks, etc.) which have been developed in the last decade in table olive fermentation and packaging for different environmental variables and microorganism, as well as their immediate applications (food safety and quality), will also be treated.