Activities of amine and phenolic antioxidants and their changes in broad beans (Vicia faba) after freezing and steam cooking

Antioxidant properties and changes in the levels of active compounds in fresh and processed broad beans were determined in the study. Activity of extracted substances was much higher against ABTS (2,2'-azino-bis [3-ethylbenzothiazoline-6-sulphonic acid]) than towards DPPH (2,2'-diphenyl-1-picrylhydrazyl) radicals. Phenolics extracted with 70% acetone were also more active comparing to amine compounds obtained with water both in experiments applying radicals and during oxidation of linoleic acid. Steam cooking and freezing had a negative influence on the content of polyphenols and in consequence on their activity. Cooking fresh broad beans decreased the content of those compounds by 16% and freezing - by over 30%, while cooking frozen material resulted in a much lower further decrease (2-8%). Processes applied on fresh material reduced the activity against ABTS ⁺ to a smaller extent (cooking by 11% and freezing by around 20%), while cooking frozen beans caused a further decrease by 10-17%.