Recently, the Food nutrition and Functional Foods Innovation Team, Institute of Food Science and Technology (IFST), Chinese Academy of Agricultural Sciences (CAAS) explored the green modification technology to reduce the digestibility and improve the applicability of rice flour. The research findings were published in the food field journal 'LWT-Food Science and Technology' (JCR 1, IF: 6.0).

Rice flour and its products are classified as high glycemic index (GI) food because of their high content of fast digestible starch. Increasing the content of resistant starch in rice flour and reducing its digestibility has become a research hotspot. However, many studies extracted the starch from rice flour firstly and then modified it, which not only waste rice protein and other nutrients but also cause environmental pollution. Therefore, this study directly studied the impact of different green modification methods on the structure, physicochemical and digestive properties of rice flour, analyzed the modified properties of rice flour from the aspects of molecular weight, lamellar structure, crystal structure, etc., to provide technical support and scientific basis for the preparation of high resistant starch rice flour.

The results showed that the content of resistant starch in rice flour treated by double enzyme compound annealing was increased from 5.00% to 16.56%, and the digestibility of rice flour treated by single enzyme compound annealing was also significantly reduced (P<0.05), indicating that the composite modification was more effective in reducing the digestibility of rice flour. The results of SAXS and FTIR showed that the rice flour after double enzyme combined annealing had the densest starch structure and the most ordered protein secondary structure. In addition, the thermal stability, water solubility and swelling power of rice flour treated by single enzyme or double enzyme combined annealing were significantly changed, while those properties of annealed rice flour were not significantly different from those of natural rice flour. Therefore, enzyme combined annealing modification technology can be used as an effective strategy to reduce the digestibility and improve the applicability of rice flour. This information will provide scientific reference for the low GI rice flour and its Products in the future.

Professor Feng-Zhong Wang and Professor Li-Tao Tong are the co-corresponding authors. The first author is Xue Gong, a postgraduate student of IFST. This study was supported financially by the "Tianshan Talent" Training Program in Xinjiang Uygur Autonomous Region (2022TSYCCX0063), the Golden Dragon Fish Innovation Fund from YIHAI KERRY, and the National Natural Science Foundation of China (31972005).

Link to the paper：https://doi.org/10.1016/j.lwt.2023.115491

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