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.