Abstract:To investigate the effects of different enzymatic hydrolysis treatments on the in vitro digestive properties of infant rice cereals and their modulation of the gut microbiota，this study employed simulated infant gastrointestinal digestion and in vitro fermentation. The digestive characteristics of mildly and deeply hydrolyzed rice cereal were systematically evaluated，and their effects on the gut microbiota of infants at different ages （6-9 months and 10-12 months） were analyzed. In vitro digestion results showed that enzymatic hydrolysis significantly increased the starch hydrolysis rate and the content of rapidly digestible starch （RDS），with deeply hydrolyzed rice cereal reaching an RDS content of 85.4% and a digestion kinetic constant K value 30.8% higher than that of control，indicating easier digestion and absorption by infants. Regarding gut microbiota modulation，deeply hydrolyzed rice cereal increased microbial richness but reduced evenness in 6-9-month-old infants and specifically enriched Lactobacillaceae. In contrast，for infants aged 10-12 months，enzymatic hydrolysis decreased microbial richness，increased evenness，suppressed Enterobacteriaceae-dominated bacteria present in the control，and promoted the growth of Firmicutes such as Lactobacillales. In summary，deep enzymatic hydrolysis not only enhances the digestibility and absorption of rice cereal in infants but also modulates gut microbiota in an age-specific manner.