In Vitro Iron Bioavailability and Antioxidant Activity of Raisins

Iron bioavailabilities and antioxidant activities of 3 generic raisin types—Golden Thompson, Dipped Thompson, and Sun-dried Thompson—were quantified and compared. Iron bioavailability was assessed with an in vitro digestion/Caco-2 cell culture model using cell ferritin formation as an index of iron bioavailability. Antioxidant activity was determined using the total oxyradical-scavenging capacity (TOSC) assay. Ferritin formation in Caco-2 cells was low for all 3 raisin types, indicating low iron bioavailability. Ethylenediaminetetraacetic acid (EDTA) enhanced iron bioavailability from raisins but ascorbic, citric, and tartaric acids showed no effect. Antioxidant activity was significantly higher in Golden Thompson than Dipped Thompson and Sun-dried Thompson, suggesting that enzymatic browning negatively affected antioxidant activity.