Preparation and properties of small-particle cassava starch

Varangkana Sanguanpong¹, Sunee Chotineeranat², Kuakoon Piyachomkwan², Christopher G. Oates³, Pavinee Chinachoti⁴, and
Klanarong Sriroth^{1 *}

¹Department of Biotechnology, Kasetsart University, Bangkok Thailand
²Cassava and Starch Technology Research Unit, National Center for Genetic Engineering and Biotechnology, Bangkok, Thailand
³Agro Food Resources (Thailand) Co., Ltd., Bangkok, Thailand
⁴Department of Food Science, University of Massachusetts, Amherst, MA, USA

ABSTRACT

Acid and enzymatic hydrolysis followed by ball milling was applied to cassava starch in order to fracture the granules. Initially, starch granules were subjected to exhaustive hydrolysis by hydrochloric acid (4%w/w) at 55°C for 24 hr or a mixture of a-amylase and glucoamylase at 55°C for 12 hr prior to ball milling (325 rpm for 3 hr). Microscopic observation and size exclusion chromatography suggested different hydrolytic pattern between acid and enzymatic treatment. By an enzyme process, granule pitting occurred with no molecular size reduction of glucans observed. In contrast, acid treatment caused the surface corrosion on starch granules with a molecular size reduction of glucans. The hydrolytic pattern of the latter was more effectively to size reduction by ball milling. Lintnerization of starch granules by acid led to the degradation first in the amorphous domains and increased the crystallinity, while the enzyme hydrolysis did not significantly alter the granule crystallinity. The resulting in an increase in internal defects and in brittleness by acid made the granule more susceptible to breakage upon milling. Hydration and gelatinization properties of acid-hydrolyzed, enzyme-hydrolyzed and ball-milled starches were also investigated.