Physicochemical properties and water migrations in freeze-dried rice noodles during rehydration: Effects of raising agent addition and water state variation

Abstract

Rapid rehydration is a critical factor to consider when evaluating the quality of instant noodles. In this study, freeze-dried rice noodles (FDRNs) were prepared by incorporating varying mass ratios (0.5–2.0 g/100g) of raising agents (RA). The influence of the RA on the physicochemical properties, water migration dynamics, and rehydration process of the FDRNs was investigated in this paper. The DMA results indicated that adding RA altered mechanical modulus and thermal temperatures in FDRNs. The morphological analysis of SEM revealed that the porous structure of FDRNs was enhanced when the RA content was 1.0 g/100g. After soaking in hot water (65, 75, and 85 °C), rehydration curves and the Peleg model could distinguish the rehydration process of FDRNs into three stages, including external wetting, internal capillarity, and core hygroscopicity. The textural properties of FDRNs were also affected by adding RA. The LF-NMR revealed an increased consumption time for the core hygroscopicity and promoted the formation of component-interacted water, suggesting that the RA added to FDRNs facilitated water migration within the core hygroscopicity stage and accelerated the rehydration rate thereafter. These data sets can provide a practical application of water-controlling strategies in producing high-quality instant rice noodles.