Modulating the in vitro digestibility of chemically modified starch ingredient by a non-thermal processing technology of ultrasonic treatment

Chemically modified starch (RS4) was commercially available as a food ingredient, however, there was a lack of knowledge on how ultrasonic treatment (non-thermal technology) modulated the enzymatic resistance of RS4. In this study, structural change of RS4 during ultrasonic treatment and its resulting digestibility was investigated. Results from scanning electron microscopy, particle size analysis, chemical composition analysis, X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy showed that ultrasonic treatment remained the granule morphology, increased the apparent amylose content, reduced the particle size, destroyed the crystalline structure, decreased the helical orders, but enhanced the short-range molecular orders of ultrasonic-processed RS4. In vitro digestibility analysis showed that the total content of rapidly digestible starch and slowly digestible starch was increased, whereas the content of resistant starch was decreased. Overall, ultrasonic treatment substantially reduced the enzymatic resistance of RS4, indicating that RS4 was not stability against the non-thermal processing technology of ultrasonic treatment.