Study on the Pre-cooking Process and Physicochemical Properties of Red Bean

Abstract

Aiming at the disadvantages of thick seed coat and difficult cooking of red beans, a red bean product that can be co-cooked with white rice was developed through the pre-cooking technology of "microwave pretreatment-soaking-steaming". Based on the optimization of pre-cooking process by response surface methodology, the appearance, color, pasting properties, texture and re-cooking properties of pre-cooked red beans with different gelatinization degree were characterized. The results showed that the increase of microwave time, microwave power, soaking time and cooking time could significantly increase the gelatinization degree of red bean. Compared with raw red beans, the color of pre-cooked red beans became dark, and the volume expanded several times. The hardness and pasting viscosity of pre-cooked red beans also decreased, but their rehydration increased by 7.5-8.8 times. In addition, there was no white core after re-cooking under simulated cooking conditions of white rice. However, with the increase of gelatinization degree, the red bean granules swelled, and the epidermis seriously ruptured. The sensory score decreased, and the rehydration first increased but then decreased. In summary, the optimal pre-cooking process was determined as: microwave power 640 W, microwave time 30 s, soaking time 6.5 h, cooking time 20 min. Under these conditions, the gelatinization degree of pre-cooked red bean was 57.52%.

Keywords

• red bean
• pre-cooking process
• microwave pre-treatment
• soaking
• re-cooking properties
• texture