Hydrolysis of native and cross‐linked corn, tapioca, and sweet potato starches at sub‐gelatinization temperature using a mixture of amylolytic enzymes
2013
Yussof, Nor Shariffa | Utra, Uthumporn | Alias, Abd Karim
The objectives of this research were to investigate the capability of a new hydrolyzing enzyme to hydrolyze native and cross‐linked starches in the granular state and to examine the influence of cross‐linking on hydrolysis. Corn, tapioca, and sweet potato starches were chemically modified by cross‐linking with 1% epichlorohydrin. The native and cross‐linked starches were subjected to hydrolysis using a new commercial enzyme, STARGEN™ 001 (a blend of α‐amylase and glucoamylase), at 35°C for 24 h, and the physicochemical properties of the starches were determined at different time points. After hydrolysis, the dextrose equivalent (DE) values of corn and tapioca starch decreased significantly after being cross‐linked (from 52.5 to 48.8% and from 35.7 to 27.9%, respectively). However, the sweet potato starch underwent a minimal reduction in DE value (from 27.3 to 26.8%). Scanning electron micrographs revealed that all cross‐linked starches had less porous granules compared to native starches after being hydrolyzed. Enzymatic erosion occurred mainly on the surface of starch granules, and the pores deepened into the interior part of the granules. The swelling power and solubility of all three cross‐linked starch decreased significantly after hydrolysis. Cross‐linking had a greater effect on pasting properties but little influence on the gelatinization properties of starch. The pasting temperature of cross‐linked tapioca starch was undetectable due to high degree of cross‐linking (92.4%). This study showed that cross‐linking had a considerable impact on the hydrolysis of corn and tapioca starch in particular by reducing the swelling power and solubility of its granules.
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