Process optimization of wheat flour crisp puffing by radio frequency and the accompanying property changes of starch.

Abstract

This research performed the process optimization of wheat flour crisp puffing by radio frequency (RF) and investigated the accompanying property changes of starch. Experiments were performed in a 6kW, 27.12MHz pilot-scale RF system. The results showed that the volume expansion was highest (220%) when the conditions were employed as follows: electrode gap (115mm); height of the sample (55mm); initial moisture content of the sample (30%). Under these conditions, the samples were puffed at 120s by RF, and changes in the starch properties were further observed. The results showed that the structure of the starch was destroyed, changing from oval and spherical in shape to fragmented. The crystal type of the starch changed from A to A+V types. Its crystal order was reduced, and the Fourier-infrared spectrum showed that the ratio of (1048/1022)cm-1 decreased from 1.142 to 1.047. The crystallinity decreased from 48.27% to 17.57%. These changes will help starch digestion and absorption in human body. These results indicated that RF puffing could become a potential development method for puffed snacks. PRACTICAL APPLICATION: In this study, the processes of radio frequency puffing wheat flour chips were optimized, and the changes of starch properties during puffing were studied. Therefore, this research provided a theoretical basis for the industrial application of radio frequency puffing.