Influence of blanching, freezing and frozen storage on physicochemical properties of broad beans (Vicia faba L)

• Chlorophyll was degraded in processed samples compared with fresh beans.
• Total color differed greatly between fresh and processed beans.
• Processed samples showed increased firmness compared with fresh beans and decreased firmness following frozen storage.
• Blanching adversely affects vegetable tissues and that deterioration reactions do not cease during frozen storage.

We evaluated the effects of blanching, freezing and frozen storage (5 months at −18 °C) on the physicochemical properties of broad beans at milk maturity stage. Times for minimal blanching (120 s) and over-blanching (180 s) were determined in a preliminary experiment. Frozen storage for five months caused 31% and 34% total chlorophyll degradation in minimally blanched and overblanched beans, respectively. Color differed greatly between fresh and blanched then frozen beans. Blanched then frozen samples showed increased firmness compared with fresh beans and decreased firmness following frozen storage, regardless of the blanching time. In sensory evaluation of cooked beans, a significant reduction in texture was found in overblanched beans compared with unblanched beans. These findings demonstrate that blanching adversely affects this vegetable and that deterioration reactions do not cease during frozen storage.