Abstract: To develop functional rice crackers suitable for diabetic patients, this study investigated the regulatory effect of addition of different levels of soy protein isolate (SPI) on the in vitro digestive properties of rice crackers and assessed its impact on blood glucose and metabolic parameters in diabetic mice. SPI‑fortified rice crackers processed by twin‑screw extrusion were produced using rice flour as raw material. The contents of rapidly digestible starch, slowly digestible starch, and resistant starch in the crackers with different addition levels of SPI were determined. Fifty mice were randomly divided into a normal group, a model group, a control group, and three experimental groups (low, medium, and high doses). A diabetic mouse model was established using a high‑sugar, high‑fat diet combined with streptozotocin injection. After 4 weeks of dietary intervention, body mass, fasting blood glucose, oral glucose tolerance, organ indices, serum glucose, and lipid metabolic markers were measured, and pathological morphology of the liver and kidney was examined. The results showed that addition of 15%–20% SPI increased significantly the digestion resistance of rice crackers. Animal experiments revealed that compared with the model group, the high‑dose experimental group showed a 22.73% reduction in fasting blood glucose, a 28.78% decrease in the area under the oral glucose tolerance curve, and a 55%, 35.78%, and 39.91% reduction in hepatic triglycerides, total cholesterol, and low-density lipoprotein cholesterol (LDL-C) levels, respectively, while high density lipoprotein cholesterol (HDL-C) content increased by 49.15%. Moreover, pathological damage in the liver and kidney was markedly ameliorated. In summary, incorporating SPI into extruded rice crackers significantly improves blood glucose levels and metabolic disorders in diabetic mice by regulating the starch digestion properties of the crackers, providing a theoretical basis and technological reference for the development of hypoglycemic rice crackers.

Key words: soy protein isolate; extrusion; rice crackers; digestibility; blood glucose