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Acid hydrolysis of waxy starches with different granule size for nanocrystal production
- Sanchez de la Concha, Brenda B., Agama-Acevedo, Edith, Nuñez-Santiago, Maria C., Bello-Perez, Luis A., Garcia, Hugo S., Alvarez-Ramirez, Jose
- Journal of cereal science 2018 v.79 pp. 193-200
- X-ray diffraction, acid hydrolysis, amaranth starch, crystal structure, nanocrystals, starch, sulfuric acid, waxy corn
- Acid hydrolysis of waxy maize and amaranth starches was achieved for nanocrystal production. Both starches are of the waxy type with an A-type crystallinity pattern. The mean granule sizes were ∼1–2 μm for amaranth starch and ∼15–18 μm for waxy maize. The starches (15 g dry basis) were subjected to acid hydrolysis with 100 mL of 3.16 M H2SO4 at 40 °C for 3, 5 and 10 days. The hydrolysis extent was higher for amaranth starch, which had a smaller granule size, although the nanocrystal yield was lower because the hydrolysis reactions were more likely to destroy the more crystalline regions. The X-ray diffraction analysis showed that the relative crystallinity increased by approximately 50% after ten days of hydrolysis, although the intrinsic crystallinity order as indicated by the Miller indices was greatly affected. A determination of the chain length distribution showed that a smaller granule size favoured the formation of shorter chains because the hydrolysis reactions were promoted by the relatively small resistance of proton transport to the inner granule region.