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Effect of Partial Acid Hydrolysis and Heat-Moisture Treatment on Formation of Resistant Tuber Starch

¹National Laboratory for Functional Food Carbohydrate, School of Agricultural Biotechnology, and Center for Agricultural Bio-materials, Seoul National University, Seoul 151-742, Korea. ²Corresponsing author. Phone: 82 2 880 4854. Fax: 82 2 873 5095. E-mail: twmoon@snu.ac.kr

Structural characteristics of resistant starch (RS) were investigated. Tuber starches, hydrolyzed with 1N HCl at 35°C for 8 hr followed by autoclaving-cooling treatment, were heated at 100°C for 16 hr after adjusting the moisture content to 20 or 30%. RS content of the tuber starches ranged from 5.4 to 22.7% depending on the source and type of treatment. Gelatinization parameters of RS isolated from partially acid-hydrolyzed starch with autoclaving-cooling followed by heat-moisture treatment (HMT) showed higher enthalpy (ΔH) values and lower peak temperature (T_p) compared with non-acid-hydrolyzed RS. R values, the difference between completion and initial temperatures, and ΔH of RS increased by HMT. The X-ray diffraction patterns of potato and sweet potato RS isolated from partially acid-hydrolyzed starch with autoclaving-cooling showed distinct sharp peaks at 15, 25, 27, and 28°, which decreased by HMT.