Bioaccessibility of phenolic compounds and antioxidant activity in raw and pickled capers

Capers are excellent sources of phenolic compounds, which possess antioxidant activity and a variety of health benefits. Capers are often not eaten fresh due to their bitterness, instead, they are usually brined and eaten as pickles. For phenolics to display beneficial effects, they should be bioaccessible. This research aimed to investigate the bioaccessibility values of phenolics in raw and pickled capers. Before and after in vitro digestion, total phenolic content (TPC), total flavonoid content (TFC), ABTS, DPPH, and FRAP antioxidant activities and individual phenolics were determined in raw (RC) and pickled capers (PC). TPC, TFC, and antioxidant activity of capers were not affected by pickling. The bioaccessibility of TPC in RC and PC was 77.8% and 72.9%, respectively. In vitro digestion decreased ABTS, DPPH, and FRAP antioxidant activity values in RC and PC significantly (p < 0.05). Rutin (quercetin-3-O-rutinoside) and kaempferol-3-O-rutinoside were found to be the main phenolic compounds before and after in vitro digestion in all caper samples. After in vitro digestion, rutin content decreased, while kaempferol-3-O-rutinoside content in capers was stable. The results suggest that capers are really good sources of bioaccessible phenolics.