Modification of waxy rice starch using a combination of β-amylase and branching enzyme to delay retrogradation

Delaying starch retrogradation is critical for enhancing the shelf life and quality of starchy foods. Branching enzyme (BE) increases the degree of branching, while β- amylase (BA) shortens glucan chains-both modifications are beneficial for retarding retrogradation. However, the combined effects of these enzymes on starch structure and retrogradation behavior remain largely unexplored. In this study, dual enzymatic modifications using BE and BA in different sequences were compared with singleenzyme treatments. Among them, the BA followed by BE treatment (BA+BE) showed the greatest potential in inhibiting starch retrogradation. This treatment significantly increased the proportions of A- and B1-chains while reducing B2- and B3-chains, and markedly decreased the setback from 272 cP to 4 cP. Moreover, the addition of 20% starch treated with BA+BE (BA+BES) exhibited the lowest extent of rice starch retrogradation. Over 21 days of storage at 4°C, the rice starch with 20%BA+BES showed minimal increases in relative crystallinity (from 9.0% to 10.3%) and hardness (from 181.5 mN to 300.0 mN). These findings demonstrate the promising potential of BA+BES in extending the shelf life of starch-based products while maintaining their quality, offering practical implications for food industry applications.