Influence of industrial sterilisation, freezing and steam cooking on antioxidant properties of green peas and string beans

Summary We found that peptides or amino acids constituted the main fractions of water‐soluble nitrogenous compounds in green peas and string beans (44% and 79%, respectively). Their proportion increased after processing, especially in frozen peas and beans (61% and 95%, respectively). The content of phenolic compounds was decreased more after industrial processing (by 40% in peas and 50–70% in beans) than after cooking (by 20% in peas and 0–35% in beans). Antiradical activity against ABTS•+ (2,2′‐azino‐bis[3‐ethylbenzothiazoline‐6‐sulphonic acid]) was much higher in aqueous extracts of peas and beans (33 and 45 μmol Trolox g−1 d.m., respectively) than in aqueous acetone extracts (approximately 17 μmol Trolox g−1 d.m. in both). In most cases, the activity decreased after processing. Both aqueous and acetone extracts of peas showed equal activity against DPPH• (2,2′‐diphenyl‐1‐picrylhydrazyl), whereas in the case of beans this activity was four times lower in aqueous than in acetone extracts. Both reductions and increases of these activities were noted after processing.