Abstract: This investigation studied the preparation of zinc-enriched rice from broken rice by extrusion using zinc lactate as zinc fortifier. Broken rice was crushed to pass through 100 mesh and the amount of zinc lactate was 2.0%. Response surface methodology was used to investigate the effects of feed moisture, screw speed, and barrel temperature on the texture characteristics of zinc-enriched rice. Under the optimized conditions: feed moisture of 20%, screw speed of 80 r/min, and barrel temperature of 100 ℃, the hardness of zinc-enriched rice was 1 339.05 g, adhesiveness was 0.75 mJ, elasticity was 0.79 mm, chewiness was 967.42 mJ, and zinc content was 450.0 mg/kg. X-ray diffraction showed that the crystallinity of starch granules in fortified rice was significantly lower than that of glutinous rice. Scanning electron microscopy showed that the zinc-fortified rice starch granules were aggregated with an irregular scale-like surface. The gelatinization temperature decreased from 77.9 to 56.2 ℃, and after enzymatic hydrolysis, the amount of reducing sugar increased by more than 23.0%, which was beneficial to the enzymatic hydrolysis of rice starch granules. The taste and appearance of cooked glutinous rice with zinc-enriched rice added at a ratio of 1:10 were good, and the zinc content was 48.0 mg/kg.

Key words: broken rice, zinc lactate, extrusion method, zinc-fortified rice, texture