Effects of ultrasound-assisted cellulase enzymatic treatment on the textural properties and in vitro starch digestibility of brown rice noodles

Abstract

The effects of ultrasound-assisted enzymatic (ult-enzymatic) treatment on the textural properties and starch digestibility of brown rice noodles were investigated. Brown rice was rich in dietary fibers, mainly insoluble dietary fiber (IDF). After the ult-enzymatic treatment, the IDF content and particle size of brown rice flour decreased, and the soluble dietary fiber (SDF) content increased. The ult-enzymatic treatment significantly influenced the pasting, thermal and rheological properties of rice flour, probably due to the changes of proximate composition and particle size distribution. Accordingly, the ult-enzymatic rice noodles with smooth surface and small air cell microstructure had better texture and cooking qualities, and slightly higher starch digestibility when compared to the untreated rice noodles. The glycemic index (GI) of the ult-enzymatic rice noodles with higher starch relative crystallinity was significantly lower than that of the polished ones. The correlation analyses exhibited that the SDF was beneficial to the reduction of starch digestibility, while had less damage to the texture of rice noodles. These results indicated that the ult-enzymatic treatment was a promising way to improve the textural properties of brown rice noodles and maintain a lower starch digestibility.