Effects of Cooking Conditions on Rupture and Damage of Ann Granules (Denatured Cotyledon Cells) in Cooked Adzuki Beans

Abstract

The composition of Ann granules (denatured cotyledon cells) in twelve varieties of Adzuki beans (Vigna angularis) cooked for an appropriate time was 0-2.4% ruptured and 0.9-10.9% damaged granules. Prolonged soaking in water before cooking resulted in the damage of the granules, although it has no discernible effect on the rupture. When beans were cooked at temperatures of 100 to 120°C for an apprpriate time, the higher temperature caused the rupture and damage of granules markedly. The cooking for over an appropriate time at 100°C or 120°C gave rise to the rupture and damage of granules. When beans were cooked in dilute hydrochloric acid solutions or buffer solutions of various pH values for an appropriate time, the proportions of both ruptured and damaged granules were the smallest at about pH6 and increased with increasing or decreasing pH, although the proportions of the damaged granules at pH1.4 were small due to the marked increase in the rupture of granules. These results suggest that the composition of Ann granules in Ann may be affected by the variety of Adzuki beans used and the processes of soaking and cooking in Ann manufacturing.