微波预处理对红豆吸水特性、外观及淀粉特性的影响

本文旨在利用微波预处理在红豆表皮形成裂缝的方式改善其在常温下的吸水速率。红豆经80~800 W微波处理10~50 s后，观察其外观和淀粉特性变化，并将其置于清水或果胶酶溶液中浸泡，探究其吸水特性。结果表明，随着微波预处理功率和时间的增加，红豆表皮逐渐形成裂缝、体积膨大、淀粉部分糊化，在25 ℃清水和0.20 mg/mL果胶酶溶液中的吸水速率均显著增加、饱和吸水率下降。其中，经800 W、30 s微波预处理后，红豆表皮产生裂缝、保持原有颗粒形状、尺寸略微变大；部分淀粉颗粒破碎和糊化、偏光十字减少；清水中吸水率提高28.78%（浸泡6 h）、饱和吸水率下降10.64%，果胶酶溶液中吸水率提高30.89%（浸泡6 h）、饱和吸水率则无明显下降。综上，微波预处理可提高红豆的吸水速率，且该提升作用可能与其表皮形成裂缝以及淀粉部分糊化有关。研究结果可为微波技术在杂粮加工中的应用提供理论指导。

Effect of Microwave Pretreatment on Water Absorption Characteristics,Appearance and Starch Properties of Adzuki Bean

This study aimed to improve the water absorption rate of adzuki bean at room temperature by producing cracks in adzuki bean epidermis via microwave pretreatment. Adzuki bean was pretreated by microwave at 80~800 W for 10~50 s, and then the changes in its appearance, starch properties and water absorption characteristics in water and pectinase solution were monitored. When the microwave power and treatment time increased, some cracks appeared on the epidermis, the volume increased, the starch was partially gelatinized, and thus the water absorption rate of adzuki bean in both water and 0.20 mg/mL pectinase solution at 25 ℃ was significantly increased. After microwave pretreatment at 800 W for 30 s, some cracks appeared on the surface, the bean remained as compact particles, and the volume was slightly increased; partial starch granules were destroyed and gelatinized, accompanying by the vanish of polarized cross; the rate of water absorption (6 h) increased by 28.78% and 30.89% in water and pectinase solution, while the saturated water absorption in water decreased by 10.64%, and showed no significant decrease in pectinase solution. Overall, microwave pretreatment could improve the water absorption rate of adzuki bean and the improvement was related to the formation of cracks on epidermis and the partial gelatinization of starch. The results could provide a theoretical guide for the applications of microwave in coarse grain processing.