Abstract:Fermented foods and beverages are a heterogeneous class of products with a relevant worldwide significance for human economy, nutrition and health for millennia. A huge diversity of microorganisms is associated with the enormous variety in terms of raw materials, fermentative behavior and obtained products. In this wide microbiodiversity it is possible that the presence of microbial pathogens and toxic by-products of microbial origin, including mycotoxins, ethyl carbamate and biogenic amines, are aspects liable to reduce the safety of the consumed product. Together with other approaches (e.g., use of preservatives, respect of specific physico-chemical parameters), starter cultures technology has been conceived to successfully dominate indigenous microflora and to drive fermentation to foresee the desired attributes of the matrix, assuring quality and safety. Recent trends indicate a general return to spontaneous food fermentation. In this review, we point out the potential risks for human health associated with uncontrolled (uninoculated) food fermentation and we discuss biotechnological approaches susceptible to conciliate fermented food safety, with instances of an enhanced contribution of microbes associated to spontaneous fermentation.Keywords: fermented food; fermentation; beverage; safety; risks; spontaneous fermentation; starter cultures; spoilage microbes; pathogens; contaminant Fermented Foods and Beverages: Scientific Dimension, Social Relevance, and Economic SignificanceA large basket of food and beverages is obtained from a microbial-based transformation of food raw materials. Different classes of microorganisms can be involved, mainly yeasts and bacteria, with a certain role of molds. The obtained fermented foods and beverages have ben staple foods for millennia, with a considerable importance in the human diet for reasons of generally enhanced shelf-life, palatability, safety and nutritional quality [1]. In fact, the desired fermentation process consists of protechnological microbial development in the given matrix, with direct and indirect effects of primary and secondary microbial metabolism. Protechnological microorganisms, in order to obtain energy and to sustain their anabolic processes, reduce the content of carbohydrates and other macromolecules available in the raw matrix, accumulating catabolic products (e.g., lactic acid, ethanol). These biological dynamics, together with the possible release of antimicrobial compounds [2], reduce the risks of undesired microbial developments (thus increasing product shelf-life and safety level). On the other hand, both primary and secondary metabolites strongly influence palatability

The quality of beer relies on the activity of fermenting yeasts, not only for their good fermentation yield-efficiency, but also for their influence on beer aroma, since most of the aromatic compounds are intermediate metabolites and by-products of yeast metabolism. Beer production is a traditional process, in which Saccharomyces is the sole microbial component, and any deviation is considered a flaw. However, nowadays the brewing sector is faced with an increasing demand for innovative products, and it is diffusing the use of uncharacterized autochthonous starter cultures, spontaneous fermentation, or non-Saccharomyces starters, which leads to the production of distinctive and unusual products. Attempts to obtain products with more complex sensory characteristics have led one to prospect for non-conventional yeasts, i.e., non-Saccharomyces yeasts. These generally are characterized by low fermentation yields and are more sensitive to ethanol stress, but they provide a distinctive aroma and flavor. Furthermore, non-conventional yeasts can be used for the production of low-alcohol/non-alcoholic and light beers. This review aims to present the main findings about the role of traditional and non-conventional yeasts in brewing, demonstrating the wide choice of available yeasts, which represents a new biotechnological approach with which to target the characteristics of beer and to produce different or even totally new beer styles.

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