Highly-branched cyclic dextrin for improvement in mechanical properties and freeze-thaw stability of κ-carrageenan gels

Highly-branched cyclic dextrin (HBCD) is a novel dextrin with promising applications in functional foods. In this study, the influence of HBCD on physiochemical properties of κ-carrageenan (KC) gels was determined by rheological measurements, thermal analysis, spectral analysis, micromorphology observation, and freeze-thaw cycle test. The results revealed that the addition of HBCD at a concentration of 2% (w/v) significantly enhanced the storage modulus and freeze-thaw stability of KC gels. During the gelation, HBCD prompted the uniform distribution of KC chains and facilitated the aggregation of KC helixes to form a compact network, enhancing the mechanical properties of KC gels. Meanwhile, the small pores within the compact network contributed to reduced water loss from the KC gels. Comparatively, the syneresis of KC gels with 2% HBCD was 19.80% after the first freeze-thaw cycle and 46.51% after complete cycles (five times), much lower than that observed in pure KC gels (66.50% after the first cycle and 68.15% after the fifth cycle). Furthermore, the attachment of HBCD to the network wall strengthened hydrogen-bonding interactions, thereby enhancing the thermal reversibility of KC gels. Overall, this research provides valuable insights and a theoretical foundation for the potential applications of HBCD in KC gels.