THESIS

1.2 Effect of preheated treatments on physiochemical properties of
resistant starch type III formation
1.2.1 Resistant starch type III formation
An aqueous high amylose rice starch (HARS; 15% w/w) were
prepared by fully dispersing the sample in distilled water. The slurry samples were
annealed at room temperature (30°C) for 1 hr with occasionally vigorous shaking. The
annealed samples were preheated at different temperatures (75, 95 and 121°C for 30-
min) and cooled to 55°C. The starch solution samples were debranched using 8 unit
pullulanase enzymes per gram starch at 55°C for 0, 2, 4, 8, 16, 24 and 48-hr in shaker
water bath (continuous shaking at 170 rpm). The retrogradation of debranched
starches were then induced at 4°C for 16-hr. Afterwards, the one cycle of freeze-thaw
process (-10/30°C) was applied to promote syneresis of the retrograded starches. The
recrystallization starch was dried at 45°C to approximate 13 % moisture content and
ground passed through a 100-mesh sieve.
1.2.2 Degree of pullulanase hydrolysis
Reducing sugar (Rds) and total sugar (Ts) in the samples,
debranched for specific times, were analyzed according to the Park- Johnson method
(Hizukuri, 1995) and the phenol-sulfuric acid reagent method (Dubois et al. 1956),
respectively. The procedures are shown in Appendix A. The hydrolysis treatment was
conducted in triplicate. The extent of debranching of HARS, using pullulanase
enzyme, was evaluated in terms of degree of hydrolysis (D.H.). Degree of pullulanase
hydrolysis was calculated by the equation:
(% of Rds after hydrolysis- Rds blank)
D.H. (%) = × 100
(% of Ts after hydrolysis - Ts blank)
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