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In this research, annealing (ANN) using plasma-activated water (PAW) was first employed to modify potato and pea starches. Compared with the conventional ANN using distilled water (DW), the granular morphology of two starches was not significantly affected by PAW-ANN. The results of X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy showed that PAW-ANN could reduce the long and short-range ordered structure of potato starch while improving the long and short-range ordered structure of pea starch. Differential scanning calorimetry (DSC) analysis indicated that PAW-ANN lowered the gelatinization enthalpy of potato starch and increased the gelatinization enthalpy of pea starch. The analysis of viscosity and dynamic rheological characteristics illustrated that PAW-ANN reduced the peak viscosity and improved the gel strength of starch pastes. PAW-ANN represents a novel modification method for modifying the structure, reducing the viscosity, improving the gel strength of starch, and is very promising for applying in starch-based hydrogels and food additives.

This study aimed to investigate the effect of the number of carboxy group on the formation of complexes between starch and fatty acids using different dicarboxylic acids and monobasic acids as ligand. The complexing index (CI) indicated that dicarboxylic acids could form complexes with starch and show stronger complexing ability than corresponding monobasic acids. Results from differential scanning calorimetry also displayed that starch-dicarboxylic acids complexes presented higher onset temperature, narrow transition peaks and higher enthalpy change, indicating the higher thermal stability and uniform and homogenous crystal of starch-dicarboxylic acids complexes. X-ray diffraction, Fourier transform infrared and Raman spectroscopy showed that the long-range and short-range order of starch-dicarboxylic acids complexes was better than that of starch-monobasic acids. According to above results, fatty acid with two carboxyl groups could form larger amount and more stability complexes than it is with one carboxyl group.