Publication: Physicochemical Properties Of Starch And Prebiotic Potential Of Oligosaccharides From Dioscorea Hispida
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Date
2018-11
Authors
Hussin, Napisah
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Abstract
The underutilised Dioscorea hispida Dennst. tuber was processed for its
starch and was evaluated for its physicochemical properties. The tuber contained
97.95% total starch comprising of amylose (25.27%) and amylopectin (72.68%).
Dioscorea hispida starch contained crude protein (0.42%), crude fat (0.23%), ash
(0.47%) and crude fiber (0.93%). The starch granules were coarse-surfaced
polyhedral shape with an average diameter of 2-4 μm. The starch exhibits B-type in
X-ray diffraction pattern and had gelatinisation peak temperature of 87 °C and
pasting temperature of 78 °C. The swelling power, solubility, water-holding and oilholding
capacities were 14.22 g/g, 5.48 g/g, 2.78 g/g and 1.14 g/g, respectively.
Different concentrations of D. hispida starch (5%, 10%, 15%, and 20%) were
hydrolysed by individual enzymes α-amylase, amyloglucosidase or pullulanase or
combination of the enzymes to yield D. hispida oligosaccharides (DHOS). The
maximum yield of DHOS (19.67 mg/g) was obtained from the hydrolysis of 10%
(w/v) of D. hispida starch with combination of α-amylase (pH 5.5; 90°C) and
pullulanase (pH 5.5; 45°C) for 6 h. The DHOS when analysed for prebiotic
characteristics was found to be resistant to hydrolysis by gastric juice at pH 3-4
(88.78-99.76% DHOS residue) for 3 h but less resistant to hydrolysis at pH 1-2.
DHOS was also found to be less resistant towards hydrolysis by gastrointestinal tract
enzymes and intestinal absorption as the remaining DHOS after hydrolysis was
ranging from 40.62-52.04%. In term of bacterial growth study, DHOS positively
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Keywords
Physicochemical Properties Of Starch And Prebiotic