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

Abstract

ABSTRACT Structural characteristics of resistant starch (RS) were investigated. Tuber starches, hydrolyzed with 1 N 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 (Δ H ) values and lower peak temperature ( T p ) compared with non‐acid‐hydrolyzed RS. R values, the difference between completion and initial temperatures, and Δ H 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.