Study on the Effect of Heat Treatment on Enhancing the Physicochemical Properties of Glutinous Rice Flour and the Quality of Sweet Dumplings

Sweet dumplings, generally made of glutinous rice flour, showed quality deterioration during long-term frozen storage. Dry heat treatment (DHT) and moist heat treatment (MHT) showed great potential to improve physicochemical and functional properties of glutinous rice flour, further enhancing the qualities of sweet dumplings. Therefore, this study examined the impact of DHT (130°C, 4 h) and MHT (100°C, 2 h) on the structural, physicochemical, and functional characteristics of glutinous rice flour of Longnuo57 (L57). DHT and MHT increased the peak viscosity, particle size, swelling capacity, water absorption capacity, elastic modulus (G'), and viscous modulus (G″) of L57, whereas they reduced the crystallinity by 1.76% (DHT) and 1.84% (MHT), respectively. MHT reduced the syneresis of L57, indicating the improved freeze-thaw stability. DHT and MHT reduced the cracking rate of sweet dumplings by 5.97% and 8.33%, respectively, during frozen storage. DHT significantly increased the hardness and chewiness of sweet dumplings. Meanwhile, DHT and MHT slowed down the starch digestibility of sweet dumplings. The principal component analysis (PCA) evaluation showed DHT resulted in superior sweet dumpling quality compared to MHT and control treatment. This study provided the reference of the influence of DHT and MHT on the properties of glutinous rice flour and the qualities of resultant sweet dumplings.