Enzymatic hydrolysis of granular native and mildly heat-treated tapioca and sweet potato starches at sub-gelatinization temperature
The effect of mild heat treatment (below gelatinization temperature) towards the susceptibility of granular starch to enzymatic hydrolysis was investigated. Tapioca and sweet potato starches were subjected to enzymatic hydrolysis with a mixture of fungal a-amylase and glucoamylase at 35 1C for 24...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier Inc.
2009
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| Subjects: | |
| Online Access: | http://irep.iium.edu.my/24836/ http://irep.iium.edu.my/24836/ http://irep.iium.edu.my/24836/ http://irep.iium.edu.my/24836/1/Food_Hydro-Colloids-2.pdf |
| Summary: | The effect of mild heat treatment (below gelatinization temperature) towards the susceptibility of
granular starch to enzymatic hydrolysis was investigated. Tapioca and sweet potato starches were
subjected to enzymatic hydrolysis with a mixture of fungal a-amylase and glucoamylase at 35 1C for
24 h. Starches were hydrolyzed in native (granular) state and after heat treatment below gelatinization
temperature (60 1C for 30min). The dextrose equivalent (DE) value of heat-treated starch increased
significantly compared to native starch, i.e., 36–50% and 27–34% for tapioca and sweet potato starch,
respectively. Scanning electron microscopy examination showed that enzymatic erosion occurred
mainly at the surface of starch granules. Hydrolyzed heat-treated starch exhibited rougher surface and
porous granules compared to native starch. X-ray analysis suggested that enzymatic erosion
preferentially occurred in amorphous areas of the granules. The amylose content, swelling power and
solubility showed insignificant increase for both starches. Evidently, heating treatment below
gelatinization temperature was effective in enhancing the degree of hydrolysis of granular starch. |
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