Evaluation of bioaccessibility of the Propolis extract prepared with L-Lactic Acid

Recently, there has been an increasing interest to develop a new non-ethanolic extraction method because of certain disadvantages of ethanolic extracts. We evaluated the bioaccessibility of phenolic compounds of propolis extracts prepared at different concentrations of lactic acid in comparison with ethanol. Following the determination of total phenolic compounds and antioxidant activity analyses, individual phenolic compounds in extracts and digested samples were determined. During in vitro digestion experiments, chrysin and naringenin were found as the major phenolic compounds in the initial samples. Pinocembrin was the most bioaccessible component among the dialyzed fractions of both ethanol and lactic acid-based solutions whereas some compounds were not detected at all. Due to the very low pH values of lactic acid-based solutions, preliminary experiments were carried out to mimic the pH levels of stomach and intestinal phases, and it was observed that lactic acid-based solutions showed higher antioxidant activity when diluted by 50% before digestion. The results suggest that lactic acid may be used as an alternative to ethanol for propolis extraction.