Influence of processing of seitan, tempeh, and firm regular tofu on protein and lipid oxidation and Maillard reaction products formation

The impact of production and cooking on protein oxidation, lipid oxidation and Maillard reaction products (MRPs) generation was evaluated for firm regular tofu, tempeh, and seitan, three plant-based alternatives to meat products. Tofu showed higher content of protein-bound carbonyls (25.5 ± 5.4 nmol/mg protein) indicating higher degree of protein oxidation, while seitan exhibited the lowest content of MRPs like N(6)-carboxymethyllysine, as revealed by LC-MS/MS. Through determination of the peroxide value and thiobarbituric acid reactive substances as well as analysis of volatile oxidation compounds by GC-MS, an overall higher lipid oxidation level was found in tofu. Likewise, a mean 92.2 % depletion of naturally occurring antioxidant tocopherol, assessed by HPLC-DAD, was observed in tofu. Furthermore, acrylamide was detected in tofu at 196.0 ± 15.4 μg/kg after frying at 190 °C. This study, therefore, concluded that practices used in tempeh and seitan processing are promising strategies to limit oxidation and Maillard reactions in food.