Partial branching enzyme treatment increases the low glycaemic property and α-1,6 branching ratio of maize starch

Partial branching enzyme treatment was used to modulate the starch fine chain structure responsible for a high content of slowly digestible starch fraction. Normal maize starch modified using branching enzyme for 4 h showed a maximum slowly digestible starch content of 23.90%. The branching enzyme hydrolysis decreased the amylose content from 32.8% to 12.8%. The molecular weight distribution of enzyme-treated starches showed a larger proportion of low molecular weight fractions appeared in the enzyme treated starch sample compare to native starch. The number of shorter chains (DP < 13) increased from 18.71% to 28.23.1%, accompanied by a reduction of longer chains (DP > 30) from 20.11% to 11.95%. 1H NMR spectra showed an increase of α-1,6 branching ratio from 4.7% to 9.4% during enzyme treatment. The increase in the amount of shorter chains and more α-1,6 linkages likely contribute to their slow digestion property. These results suggest that starches treated with partial branching enzyme synthesis a novel branched structure with slowly digestible character.