The use of yeasts as starter cultures was boosted with the emergence of large-scale fermentations in the 20th century. Since then, Saccharomyces cerevisiae has been the most common and widely used microorganism in the food industry. However, Candida species have also been used as an adjuvant in cheese production or as starters for coffee, cocoa, vegetable, meat, beer, and wine fermentations. A thorough screening of candidate Candida is sometimes performed to obtain the best performing strains to enhance specific features. Some commonly selected species include C. pulcherrima (teleomorph Metschnikowia pulcherrima) (wine), C. parapsilosis (teleomorph Monilia parapsilosis) (coffee), C. famata (teleomorph Debaryomyces hansenii) (cheese), and C. zeylanoides (teleomorph Kurtzmaniella zeylanoides) and C. norvegensis (teleomorph Pichia norvegensis) (cocoa). These species are associated with the production of key metabolites (food aroma formation) and different enzymes. However, safety-associated selection criteria are often neglected. It is widely known that some Candida species are opportunistic human pathogens, with important clinical relevance. Here, the physiology and metabolism of Candida species are addressed, initially emphasizing their clinical aspects and potential pathogenicity. Then, Candida species used in food fermentations and their functional roles are reported. We recommended that Candida not be used as food cultures if safety assessments are not performed. Some safety features are highlighted to help researchers choose methods and selection criteria.

In recent years, the development of non-dairy probiotic beverages has been stimulated due to the increase in the number of people with milk protein allergies, lactose intolerance, and those that are vegetarian and vegan eating. These functional foods have a number of health benefits, combining properties of plant matrices and probiotic effects. However, a major challenge in formulating these beverages is the limited number of adapted microbial strains with probiotic phenotype that promote desirable sensory characteristics, besides remaining viable in the final product for long periods. Therefore, this review aimed to provide an overview of the production of traditional non-dairy fermented beverages produced in the world and to show the biotechnological potential of these foods as a source of strains presenting a probiotic phenotype. In addition, the latest developments on the role of lactic acid bacteria, Bifidobacterium, and yeast species in the development of new probiotic beverages from the fermentation of fruit and cereal are discussed. Finally, some aspects related to food safety issues are shown.

Natural vinegar fermentation is a complex process influenced by the interplay between microbial communities and metabolites. This study examined the interplay between the microbiome and the metabolome over a three-month period, with samples collected every ten days. Using Illumina sequencing and chromatographic techniques (HPLC and GC-MS), we mapped microbial shifts and metabolite profiles. Early fermentation showed a diverse microbial presence, including genera such as Cronobacter, Luteibacter, and Saccharomyces. A stable microbial ecosystem established between days 15 and 70, characterized by the dominance of Leuconostoc, Gluconobacter, and Saccharomyces, which facilitated consistent substrate consumption and metabolite production, including various organic acids and ethanol. By day 70, Acetobacter prevalence increased significantly, correlating with a peak acetic acid production of 12.4 g/L. Correlation analyses revealed significant relationships between specific microbes and volatile organic compounds. This study highlights the crucial roles of these microbes in developing sensory profiles suited for industrial applications and proposes an optimal microbial consortium for enhancing vinegar quality. These data suggest that an optimal microbial consortium for vinegar fermentation should include Saccharomyces for efficient alcohol production, Leuconostoc for ester-mediated flavor complexity, and Acetobacter for robust acetic acid production. The presence of Komagataeibacter could further improve the sensory and functional qualities due to its role in producing bacterial cellulose.