The role of various dairy food matrices on the amount and <i>in vitro</i> bioaccessibility of phenolics in elderberries

Purpose Elderberry (Sambucus nigra) fruits are rich in bioactive components, specifically in anthocyanins. In this study, freeze-dried and powdered elderberry fruits were added to milk, yoghurt and kefir samples at ratios of 5, 10 and 15% (w/w) to fortify these dairy products at home scale, and final products were monitored to understand the behaviour of bioactive compounds. Design/methodology/approach The action of bioactive compounds was examined before and after in vitro gastrointestinal digestion by the analysis of total anthocyanin content, total phenolic content and antioxidant activity assays as well as the HPLC-PDA system on the first day of preparation. Moreover, the effect of three days of storage on individual phenolic compounds was evaluated. Findings Kefir samples exhibited the highest total anthocyanin content levels among prepared products (255±4-702±65 µmol cyanidin-3-glucoside eq/100 g), which is followed by yoghurt samples. Individual phenolics in samples prepared at the same concentrations behaved almost similarly with each other during gastric digestion phases (p &amp;gt; 0.05), whereas intestinal digestion phases caused significant differences, and phenolics in yoghurt samples exhibited higher values than others (p &amp;lt; 0.05). The stability of bioactive compounds in samples tended to decrease during storage; however, as observed during gastrointestinal digestion, yoghurt and kefir samples provided better matrices than milk to maintain the presence of bioactive compounds (p &amp;lt; 0.05). Originality/value Previous studies have indicated that elderberry fruits contain high levels of bioactive compounds, and these fruits have been used to fortify different food matrices. However, this research paper investigates the interaction between three selected dairy products and elderberry powder with each other for the first time.