Effect of Holding Condition before Freezing on Quality in Immature Black Soybeans 'Tanbaguro' Served as a Vegetable

Abstract

Effect of holding condition before freezing after harvest on quality in immature black soybeans (Glycine max L. cv. Tanbaguro) was examined to elucidate a suitable holding condition after harvest before freezing processing. Effect of harvest period on quality of immature black soybeans during holding period was also examined. Sucrose content of immature black soybeans held at room temperature decreased during holding period. The sucrose level decreased from 100% (immediately after harvest) to 87, 55 and 31% during the holding for 8, 24 and 48 hours, respectively. It was almost the same with change in free amino acid content as with change in sucrose content under several holding conditions. The immature black soybeans quality, which was evaluated by the green color of pods and the components for taste, was maintained well for 24 hours with cold storage (5°C) or storage with ice. The quality of immature black soybeans held at room temperature was maintained with soaking in water or packaging in a polyethylene bag. The green color of pods at the first half of harvest period was bright, and the color was maintained during the holding for 72 hours. The green color of pods at the latter half was slightly yellowish, and the color faded during the holding at room temperature for 72 hours. Sucrose content in all of the holding conditions was higher at the latter half than at the first half. The immature black soybeans at the first half of harvest period was suited for the material attached importance to the green color of pods, whereas those at the latter half was suited for the material attached importance to the taste.