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• A novel cold-set rice starch (RS)/heat-set curdlan composite gel systems prepared. • The RS-curdlan interaction affects the composite gel's structure and properties. • The 5:5 composite gel starts to show rheological properties dominated by curdlan. • Curdlan inclusion in RS enhances gel structure density and mechanical properties. • A schematic proposed for temperature-induced conformational change. In pursuit of advancing the understanding of composite gel systems, this study delves into the intricate realm of rheology, structural elucidation, and mechanical attributes. Specifically, it scrutinizes the symbiotic interplay between rice starch, a cooling-set gel, and curdlan, a thermo-irreversible heating-set gel. A higher curdlan content enhances the inter-chain hydrogen bonding between rice starch and curdlan, resulting in a denser gel structure and thus increased moduli, solid-like behavior, and mechanical properties, and reduced frequency-dependence, especially at high temperatures (>65 °C). For example, with 50 % curdlan incorporation, G ′ (90 °C) improved by 252 %. Notably, thermal treatment can compromise the structural integrity of the rice starch gel, reducing strength and softening texture. However, this textural degradation can be effectively mitigated with, for example, 30 % curdlan incorporation, resulting in a 55-fold hardness increase at 85 °C. The knowledge gained from this work offers valuable guidance for tailoring starch-based gel products to specific properties. [ABSTRACT FROM AUTHOR]

Highlights • Starch nanoparticles (SNPs) were modified by annealing (ANN). • The relative crystallinity of SNPs significantly increased after annealing treatments. • The ANN-SNPs showed higher gelatinization temperature and lower melting range. Abstract Annealing offers a facile and green approach to the modification of starch. This study was the first to investigate the effect of annealing on the properties of waxy rice starch nanoparticles (SNPs). The spherical morphology of SNPs hardly changed after annealing, and the nanoscale size of the SNPs was maintained in the range of 50–120 nm. The relative crystallinity of modified SNPs increased from 53.71% to 63.46% after annealing at 55 °C for 48 h. The annealing treatment increased the melting temperature from 78.3 °C to 95.7 °C, but decreased the melting range from 30.8 °C to 25.3 °C. The increased 1047 cm−1:1022 cm−1 ratio suggested that annealing resulted in an efficient packing of double helices. This work suggests that annealing, a safe and green method, produces modifications which can improve the properties of SNPs and therefore expand their applications in the fields of food, nutraceuticals, and other materials. [ABSTRACT FROM AUTHOR]