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Hot-Water Solubilities and Water Sorptions of Resistant Starches at 25°C

¹Department of Food & Nutrition and HERI, Chonnam National University, Gwangju 500-757, Korea. ²MGP Ingredients Inc., Atchison, KS 66002-0130. ³Department of Grain Science & Industry, Kansas State University, Manhattan KS 66506. ⁴Corresponding author. E-mail: pas@wheat.ksu.edu. Phone: 785-532-4088. Fax: 785-532-7010.

Resistant starches (RS) were prepared from wheat starch and lintnerized wheat starch by autoclaving and cooling and by cross-linking. Heat-moisture treatment also was used on one sample to increase RS. The experimental resistant starches made from wheat starch contained 10–73% RS measured as Prosky dietary fiber, whereas two commercial resistant starches, Novelose 240 and 330, produced from high-amylose maize starch, contained 58 and 40%, respectively. At 25°C in excess water, the experimental RS starches, except for the cross-linked wheat starch, gained 3–6 times more water than the commercial RS starches, and at 95°C gained 2–4 times more. Cross-linked RS4 wheat starch and Novelose 240 showed 95°C swelling powers and solubilities of 2 g/g and 1%, and 3 g/g and 2%, respectively. All starches showed similar water vapor sorption and desorption isotherms at 25°C and water activities (a_w) < 0.8. At a_w 0.84–0.97, the resistant starches made from wheat starch, except the cross-linked wheat starch, showed ≈10% higher water sorption than the commercial resistant starches.