Mushroom (Agaricus bisporus), Its Polyphenoloxidase, and Polyphenolics Affect In Vitro Iron Availability

In vitro iron availability (IA) from egg white meals was 14–17% of total meal iron. When mushroom ( Agaricus bisporus ) was added to egg white meals, IA decreased. The initially low IA from whey protein concentrate meals (<1% of meal iron) was enhanced by mushroom. Sodium benzoate or sodium bisulfite added to egg white/ mushroom meals increased IA. Addition of polyphenoloxidase (PPO) and gallic acid to egg white meals decreased IA; however, gallic acid alone increased IA. Blanching mushrooms eliminated PPO activity and increased IA of egg white/mushroom meals, but it was still less than for egg white meals. Sodium bisulfite added to blanched mushroom/egg white meals increased IA above that for egg white meals. Results are consistent with the interpretation that enzymatic browning can decrease IA.