Effects of Different Freezing Temperatures on the Quality of Rice Dumpling Dough

To investigate the effects of different freezing temperatures on the quality of rice dumpling dough, this paper investigated the effects of freezing at −20, −30, −80, −196 ℃ (liquid nitrogen) on the physicochemical indexes of rice dumpling dough, such as texture characteristics, water loss rate and color. The water distribution and microstructures of rice dumpling dough were studied by NMR, MRI, SEM and other analytical techniques. The results showed that the lower the freezing temperature, the faster the freezing rate. With the decrease of freezing temperature, the water loss rate and light transmittance of rice dumpling dough improved significantly (P<0.05), and there was no significant difference (P>0.05) in whiteness, and the magnitude of textural changes was small. The microstructure of the rice dumpling dough was more complete at ultra-low temperature freezing. During the freezing process, the internal water state of the rice dumpling dough was changed, free water and multilayer water were transformed into bound water, liquid water molecules were reduced, and hydrogen proton density was decreased. Combined with the actual situation, the freezing temperature below −30 ℃ could significantly improve the quality of rice dumpling dough.