The aim of the present work was to investigate the potential prebiotic action of Goji berry powder on selected probiotic bacteria grown in a nutritive synthetic substrate and in simulated gastric and intestinal juices. Different probiotic strains of Bifidobacterium and Lactobacillus were grown in these substrates with or without the addition of encapsulated goji berry extracts of different polysaccharide and polyphenol contents. The results proved that the addition of the extracts promoted the proliferation of probiotic strains and, in particular, increased the number of bacterial colonies of Bifidobacterium animalis subsp. lactis (Bb12), Bifidobacterium longum (Bb46), and Lactobacillus casei by 2, 0.26, and 1.34 (log cfu/mL), respectively. Furthermore, the prebiotic effect seems to be correlated to Goji berry polysaccharides and/or polyphenols, higher contents of which (under the tested concentrations) could increase the stress tolerance of B. lactis and B. longum in a simulated gastrointestinal environment. According to the findings of the present research, it can be suggested that the Goji berry encapsulated extracts could be used as prebiotic additives in food or nutraceuticals, in order to stimulate growth or protect the viability of probiotic strains of Bifidobacterium and Lactobacillus.
Keywords: Bifidobacterium; Goji berry extracts; Lactobacillus; encapsulation; nutraceutical; polyphenols; polysaccharides; prebiotic; probiotic.