Effect of in vitro gastrointestinal digestion on the antioxidant activity of protein hydrolysates prepared from Cape hake by‐products

Summary The antioxidant activity of fish protein hydrolysates may change in the digestive tract during the human gastrointestinal digestion depending on their preparation conditions. Thus, the objective of this study was to assess the antioxidant properties of Cape hake hydrolysates prepared by three different methods ( HPH ‐A, HPH ‐B and HPH ‐C) and the effect of their in vitro gastrointestinal digestion on their antioxidant properties. HPH ‐A showed the highest reducing power, while HPH ‐B and HPH ‐C exhibited the highest OH antiradical activity. Fe 2+ ‐chelating activity was similar for all hydrolysates, but HPH ‐C had a higher Cu 2+ ‐chelating activity comparable to that of EDTA . The in vitro gastrointestinal digestion of hydrolysates caused a decrease in the DPPH inhibition, but an increase in scavenging ABTS in all hydrolysates. Copper‐ and iron‐chelating activities increased after digestion of hydrolysates. The results showed that the gastrointestinal digestion of HPH s generally increased their antioxidant properties.