Effects of Zinc Fortification and Ultrasonic Treatment on the Physicochemical Properties, Structure, and
Hanwen Liang1, Jinyan Yu1, Tosin Michael Olajide2
1Food Nutrition and Chronic Disease Intervention Laboratory, School of Life sciences, Shanghai University, Shanghai, China.
Abstract:
Fortification during germination is an effective strategy for improving the physicochemical properties of cereal starch. Therefore, this study investigated the synergistic effects of Zn fortification (0-200 mg/L) and ultrasonic treatment (200 W, 53 kHz, 15 min) on the functional properties and digestibility of germinated black rice (GBR) starch, with a focus on associated structural changes. The fortification treatment decreased starch and increased reducing sugar contents. It also lowered the amylose content, relative crystallinity, and FT-IR intensity ratio of starch. These structural changes altered starch functionality. The starch from GBR treated with 100 mg/L Zn combined with ultrasound (UGBR-Zn100) exhibited the highest swelling power and the lowest relative crystallinity. The solubility and swelling power of UGBR-Zn100 starch at 95°C increased to 15.90% and 22.39 g/g, while gelatinization enthalpy, peak viscosity, and trough viscosity decreased to 1.13 J/g, 2338.00 cP, and 1422.00 cP, respectively, with no significant change in the water absorption capacity. In vitro digestion results indicated that the fortification treatment increased the rapidly digestible starch content and digestibility. Meanwhile, zinc fortification and ultrasonic treatment showed an interaction effect on the increase in starch solubility and swelling power.
