Structural and functional characteristics of butyrylated maize starch

Butyrylated maize starch (MSB) samples were prepared by the water-phase method using maize starch as the raw material and butyric anhydride as the esterifying agent. MSB samples with different degrees of substitution (DSs) were prepared by changing the addition amount of butyric anhydride. The crystal structures, starch-granule appearances, pasting properties, in vitro digestibilities, and fermentation characteristics of the MSBs were investigated and compared with those of native maize starch and acetylated maize starch (MSA) as controls. Fourier-transform infrared spectroscopy demonstrated that ester carbonyl groups were successfully incorporated into the starch molecules. The degree of crystallinity gradually decreased with increasing DS, with the surfaces of the MSB granules becoming more fragmented and the granules becoming more flocculated. The peak viscosity of the MSB decreased from 832 to 186 mPa s with increasing DS. Additionally, the resistant starch content increased from 18.17% to 53.80% with increasing DS. During in-vitro fermentation, the concentrations of butyric acid produced by MSB was 480.85–786.09 μmol/L. MSA produced higher concentrations of acetic acid, but the concentration of butyric acid produced by MSA was only 1.39 μmol/L. Thus, the study indicates that MSB has a better capacity for producing butyric acid upon in-vitro fermentation.