Prebiotics as protectants of lactic acid bacteria

ROMANO NELSON; TYMCZYSZYN E,; MOBILI, P; GOMEZ ZAVAGLIA, A.

Bioactive Foods in Promoting Health: Probiotics, Prebiotics, and Synbiotics

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Año: 2015; p. 155 - 164

The important role of lactic acid bacteria as starters in theelaboration of dairy and pharmaceutical products highlights the requirement ofappropriate processes for their preservation, among which freezing, freeze-drying and spray-drying are the most widely used. Moreover, when these microorganisms are deliveredin food matrices, both food matrices and technological processes may also bedetrimental.During all these processes, the decreaseof water activity is the main cause of damage on the bacterial structures, cellmembranes being the first target of this damage.The injury caused by dehydration usually destroys the barrier of ion permeation,affecting the physicochemical properties of membranes and leading in the end toa decrease in bacterial viability. To preclude these detrimental effects,preserving lipid membranes is essential, and sugars like trehalose, sucrose andother disaccharides have been traditionally used to this aim.Prebioticshave been defined as non-digestible food components that beneficially affectthe host by selectively stimulating the growth and/or activity of one or alimited number of bacteria in the colon, thus improving host health. Therefore,the ingestion of food ingredients with well-known prebiotic properties canpositively modulate the intestinal microbiota. From a chemical point of view,most of the prebiotics identified up to now are non-digestible oligosaccharides(NDOs). Then, why not to use them as bacterial protectants.Certainprebiotics (i.e.: fructans) act as naturalprotectants against dehydration in plants. Indeed, it is not surprising that fructansaccumulate in plants exposed to cold and dry environments, and are absent intropical and aquatic environments. This observation strongly supports theactivity of different research groups in shedding light on their role as protectantsagainst dehydration of membranes and lactic acid bacteria. Becauseof their structure of oligosaccharides, NDOs become attractive ingredients forthe development of new functional foods, their properties going beyond healthrelated effects. In this context, NDOs may have a protective role in probioticcontaining functional foods, also providing technological desirable properties(i.e.: viscosity, texture, etc).Furthermore, the refractance of prebiotics to hydrolysis and absorption in theupper part of the gastrointestinal tract ensures bacterial protection up to thearrival to the gut. As the health related effects of NDOs have been widelyexplored, this chapter will be addressed to the protective properties ofprebiotics, a much less explored approach.