Valorization of Coffee Cherry By-Products Through Fermentation by Human Intestinal Lactobacilli in Functional Fermented Milk Beverages

During coffee production, the removal and disposal of the coffee bean-surrounding layers pose an environmental problem. In this work, we examined the effects of several aqueous coffee cherry extracts on the growth and metabolism, biofilm formation, antioxidant capacity and antimicrobial activity of six lactobacilli from the INIA collection and a commercial probiotic <i>Lactobacillus rhamnosus</i> GG strain. Growth medium supplementation with different coffee cherry extracts (at 40%) stimulated strain growth and metabolism. The ground cherry pulp extract (CPE) with the highest total polyphenol content was selected for further use. This CPE contained alkaloids, phenolic acids and flavonoids. Upon CPE supplementation, some strains significantly (<i>p</i> < 0.01) increased biofilm formation, while all strains increased antioxidant capacity and antimicrobial activity. After preliminary tests, we developed three bifunctional dairy products, containing 20% CPE and fermented with strains INIA P495, INIA P708 or GG. These strains maintained high levels after manufacture, refrigerated storage, and throughout an in vitro procedure mimicking gastrointestinal tract conditions. Compared to controls, CPE-containing products showed increased levels of total polyphenol compounds, antioxidant capacity and antimicrobial activity, together with positive sensory characteristics. CPE and these selected strains could thus be used to elaborate innovative functional fermented milk products.