Liquid-phase food fermentations with microbial consortia involving lactic acid bacteria: A review.

Microbial associations are frequent in traditional fermented foods and beverages, conferring upon them their characteristic organoleptic, physical and nutritional properties. Moreover, the search for novel products that satisfy the needs of consumers, especially foods with health-giving properties, means that new combinations of microorganisms are tested on a wide variety of substrates. In these microbial consortia, lactic acid bacteria (LAB) are frequently the major bacterial starters, usually combined with other species such as propionic and acetic acid bacteria and yeasts. The ability of LAB to produce a wide variety of metabolites is a determining factor in the establishment of associations with the interacting microbiota, which can be positive, negative or neutral. In liquid-phase fermentations, the control of these interactions represents a great challenge, due to the rapid rate of bioconversion and the direct liberation of the metabolites into the medium. Therefore, the understanding of the co-culture dynamics is of vital importance. The present review compiles data referring to the microbial consortia involving LAB, traditionally used to obtain artisanal products, as well as the new associations proposed and tested for the development of novel fermented liquid foods and beverages. The different types of interactions that have been found in these microbial consortia are discussed, including some mathematical models that have been proposed to simulate and control the development of fermentations. Some of the strategies, techniques and devices that are being developed and implemented to improve the efficiency of co-cultures are finally presented.