Molecular Techniques in Food Fermentation: Principles and Applications

Abstract

The dynamics of growth, survival, and biochemical activity of microorganisms in fermented foods are the result of stress reactions in response to the changing of the physical and chemical conditions into the food micro-environment, the ability to colonize the food matrix and to grow into a spatial heterogeneity, and the in situ cell-to-cell ecological interactions which often happen in a solid phase. To this regard, estimates of true microbial diversity in fermented food products are often difficult chiefly on account of the inability to cultivate most of the viable bacteria or to evaluate stressed cells. Traditional methods of microbial enumeration, identification, and characterization are insufficient for monitoring specific strains in complex, mixed-strain microbial communities. In the last decade, due to the use of molecular methods, our knowledge about the microbial diversity of microbial ecosystems has dramatically increased. In particular, new and highly performing culture-independent and culture-dependent molecular techniques are now available to study food-associated microbial communities. While the former are helping to afford peculiar problems related to composition and population dynamics of heterogeneous microbial communities in complex food matrices, the latter are expanding our knowledge about taxonomic diversity of the food-related microflora. Molecular approaches to study the evolution of microbial flora could be useful to better comprehend the microbiological processes involved in food processing and ripening, improve microbiological safety by monitoring in situ pathogenic bacteria, and evaluate the effective composition of the microbial populations. In this chapter, a general overview of molecular methods to study microbial populations in food fermentation will be given. Recent advances and technical description of these methods will be outlined.