CONICET | Buscador de Institutos y Recursos Humanos

Among functional foods, fermented milks containing probiotic bacteria dominates the global market (Saxelin, 2008; Figueroa-González et al. 2011). In these products, functionality is given by a combination of their bioactive components such as viable probiotic bacteria and lactic acid starters, peptides derived from milk fermentation and other components such as exopolysaccharides or products derived from lactic acid bacteria metabolism in milk (bacteriocins, organic acids, for example) (Vinderola et al. 2008). Cell viability of probiotic bacteria along production and storage of probiotic foods is a prerequisite in order to achieve their claimed health benefits (Ouwehand and Salminen 1998; Galdeano and Perdigón 2004). Many other foods, other than fermented milks or fresh cheeses are not, up to now, suitable vehicles for incorporating probiotic bacteria, since their process of manufacture (high temperature) or storage (room temperature) or their physicochemical characteristics (too acid, too low water activity, too high osmotic pressure) render them inadequate to carry viable microorganisms. During milk fermentation, a range of secondary metabolites (bacteriocins, exopolysaccharides) are produced by lactic acid bacteria or release by them from milk proteins, such as bioactive peptides (Vinderola et al. 2008). Many of these components have been associated with health promoting properties such as mucosal immunomodulation, antihypertensive, antithrombotic, opioid and antimicrobial activities and participation in many nutritional pathways (Silva and Malcata 2005). Buttermilk is a low-cost by-product of the dairy industry obtained during butter manufacturing. In a previous study (Burns et al. 2008), we reported the capacity of buttermilk to support the growth of lactobacilli. Although the nutritional and functional value of skim milk components is well understood, buttermilk has only recently gained attention as a potential source of functional ingredients, and the production of buttermilk fractions as value added ingredients would have a great economic impact (Corredig et al. 2004). In a following work, (Burns et al., 2010), we showed that buttermilk was a suitable substrate for the fermentation with a proteolytic strain of Lactobacillus and for the release of peptide fractions able to be spray-driedand to modulate the gut mucosa in vivo. The final goal of this series of works is to obtain, by spray-drying, the bioactive compounds released by an authoctonous strain of Lactobacillusin buttermilk, to confer functionality to some foods not always able to carry viable probiotic bacteria, such as cereal bars, cookies or too-acidic drinks.Taking into account that many technological variables might influence the functionality of food (Vinderola et al. 2011), the aim of this work was to determine the influence of the degree of proteolysis of buttermilk proteins on the functionality of fermented buttermilk. Different degrees of proteolysis were achieved by using different substrate concentration and pH-controlling agents.

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