Australian native fruit Davidson’s plum in yoghurt: prebiotic properties and influence on gut microbiome in vitro

Ooray/Davidson’s plum (Davidsonia pruriens) is a native Australian tree that produces fruits rich in antioxidants, fibre, anthocyanins and other nutrients that have been consumed by Aboriginal and/or Torres Strait Islander peoples for many thousands of years. Their prebiotic properties have not been well documented in the literature. In this study, additions of D. pruriens as a source of prebiotics were evaluated by preparing yoghurts containing probiotic bacteria Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis with several different concentrations of D. pruriens powder (0, 0.5, 1, 2.5 and 5% (w/v)) and measuring yoghurt microbiological properties during 4 weeks of refrigerated storage. Viability of probiotics after in vitro digestion and colonic fermentation were also analysed. Microbiological shelf life was not affected by the additions of D. pruriens in yoghurt. Probiotic L. acidophilus and starter culture bacteria Streptococcus thermophilus survived well (~6 log CFU/g) in all types of yoghurts up to 2 weeks of storage. Yoghurt was shown to be a suitable product to enhance the viability of probiotic lactic acid bacteria during the colonic fermentation. D. pruriens 5% in yoghurt had a significantly higher survival after 48 h indicating potential beneficial effects of D. pruriens on probiotics and gut microbiota.