Abstract:

Arrowhead resistant starch (RS) was prepared by acid hydrolysis followed by microwave heating. New continuous compact structure was formed in arrowhead RS. Elementary crystallites were the major components of arrowhead RS crystal. The crystalline pattern of arrowhead RS was changed into C type and the crystallinity was 23.62%. The maximum absorption wavelength of arrowhead RS-iodine complex was 564.40 nm. As more RS was formed, there was a significant decrease in the degree of polymerization (DP) and the DP of purified arrowhead RS was 22.94, and most soluble amylose was converted into insoluble amylase, but less change in amylose content was observed. Infrared spectral analysis showed arrowhead RS contained primary and secondary alcoholic hydroxyl groups and the structure of α-D-pyran ring. Structurally, arrowhead RS presented only more formed hydrogen bonds when compared with its native counterpart. Therefore, the modification for arrowhead starch is physical modification. Moreover, arrowhead RS also exhibited lower solubility and transparency but higher water-holding capacity in comparison with its native counterpart.

Key words: arrowhead, resistant starch, physico-chemical properties