Impact of the Fenton process in meat digestion as assessed using an in vitro gastro-intestinal model

• Oxygen free radicals were identified in an in vitro gastro-intestinal model.
• Iron is a powerful catalyst of the radical production during digestion.
• The oxidations generated by oxygen free radicals were estimated on myofibrils.
• Oxidations negatively impacted myofibrillar protein digestibility.

The production of oxygen free radicals catalysed by non-haem iron was investigated in an in vitro mimetic model of the digestive tract using specific chemical traps. Superoxide radicals (O2∗−) and their protonated form (hydroperoxyl radicals, HO2∗) were detected by the reduction of nitroblue tetrazolium into formazan, and hydroxyl radicals (OH∗) were detected by the hydroxylation of terephthalate. Under gastric conditions, O2∗−/HO2∗ were detected in higher quantity than OH∗. Increasing the pH from 3.5 to 6.5 poorly affected the kinetics of free radical production. The oxidations generated by these free radicals were estimated on myofibrils prepared from pork rectus femoris muscle. Myofibrillar lipid and protein oxidation increased with time and oxidant concentration, with a negative impact on the digestibility of myofibrillar proteins. Plant food antioxidants considerably decreased free radical production and lipid oxidation but not protein oxidation.