Sulfation Modification and Properties Analysis of Soluble Dietary Fiber from Rosa sterilis Pomace

In this paper, the Rosa sterilis soluble dietary fiber (RSDF) was used as raw material. The degree of substitution was used as the evaluation index, the RSDF was modified by sulfate esterification (Sulfamic acid-N,N-dimethylformamide method) and prepared sulfated soluble dietary fiber (SSDF). The influence of RSDF and N,N-dimethylformamide solid-liquid ratio (g/mL), RSDF and sulfamic acid ratio (g/g), reaction time (min) and reaction temperature (℃) on the degree of substitution were investigated, and three levels of the four single factors were selected for orthogonal test to obtain the best esterification process. Finally, the difference between RSDF and SSDF was analyzed by infrared spectroscopy and differential scanning calorimetry. The results showed that the optimal conditions were solid-liquid ratio of 1:80 g/mL, sulfamic acid ratio of 1:4 g/g, reaction time of 195 min and reaction temperature of 80 ℃. Under these conditions, the substitution degree of SSDF was 1.84±0.19. Infrared spectrum showed that the characteristic peak of SSDF at 1254 cm⁻¹ and 893 cm⁻¹ appeared after the sulfated modification, indicated that the sulfated was successful. Differential scanning calorimetry analysis showed that the melting temperature of SSDF was 140 ℃ and its thermal stability was slightly lower than RSDF.