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Sorption isotherm and state diagram for indica rice starch with and without soluble dietary fiber
- Wan, Jie, Ding, Yueping, Zhou, Guohui, Luo, Shunjing, Liu, Chengmei, Liu, Fei
- Journal of cereal science 2018 v.80 pp. 44-49
- dietary fiber, drying, freezing, glass transition, glass transition temperature, gravimetry, models, rice, rice starch, sorption isotherms, storage quality
- Moisture sorption isotherms and state diagrams for indica rice starch (IRS) and indica rice starch-soluble dietary fiber (IRS-SDF) were developed to investigate the effect of SDF on the stability of IRS. Sorption isotherms of IRS and IRS-SDF were determined by the static gravimetric method and the data were modeled by Guggenheim–Anderson–de Boer (GAB) model. The GAB monolayer moisture contents were calculated to be 7.43 and 8.37 g/100g (dry basis) for IRS and IRS-SDF, respectively. The state diagram was composed of the glass transition line and freezing curve, which were fitted according to Gordon–Taylor and Chen models, respectively. The ultimate maximum-freeze-concentration conditions were calculated as characteristic glass transition temperature (Tg’) of −42.5 °C and −31.5 °C with characteristic solids content (Xs') being 0.71 and 0.72 g/g (wet basis), and characteristic temperature of end point of freezing (Tm’) being −18.2 °C and −13.8 °C for IRS and IRS-SDF, respectively. The state diagrams and sorption isotherms of IRS and IRS-SDF have great significance for evaluating storage stability, optimizing drying and freezing processes.