Sheep milk cheese supplementation with açai extract and human bifidobacteria improves antioxidant capacity and...

Supplementation of dairy products with nutrients from different sources and/or probiotic bacteria are common ways to increase functionality and improve health-promoting properties. Due to their capacity to transform polyphenols into readily bioavailable metabolites, some Bifidobacterium strains are promising candidates for supplementation purposes. Here, we studied the effects of a polyphenol-rich açai (Euterpe oleracea Mart.) extract (AE) on several human Bifidobacterium strains, and developed a synbiotic sheep milk cheese with açai extract and a selected strain. B. pseudolongum INIA P2 was chosen as the most suitable candidate after evaluating its growth, antioxidant capacity and biofilm-forming ability in the presence of AE. Subsequently, the characteristics of sheep milk cheeses containing either an AE, the INIA P2 strain, or both, were compared with a control cheese. B. pseudolongum INIA P2 was able to maintain sufficient viable microbial levels, in cheeses and after simulated major gastrointestinal conditions, to sustain a therapeutic effect. AE addition to cheese curd resulted in substantial effects. Experimental cheeses with AE showed higher levels of proteolysis as determined by the o-phthaldialdehyde test. Folin-Ciocalteau and ferric reducing antioxidant power assays revealed increased total phenolic content and antioxidant capacity of AE-containing cheeses. AE modified cheese color, and promoted a more active cheese microbial metabolism, denoted by differences in levels of organic acids and volatile compounds, which were assayed by HPLC-DAD and GC-MS, respectively. The synbiotic sheep milk cheese with açai extract and B. pseudolongum INIA P2 reached the highest levels of proteolysis, total phenolic content, antioxidant capacity and some organic acids and volatile compounds. Apart from being appealing for consumers allergic or intolerant to cow milk, the synbiotic cheese may offer health-promoting properties, independent of endogenous gut microbiota.