Effect of Critical Melting Combined with Freeze-thawing Treatment on Physicochemical and Structural Properties of Cassava Starch/Konjac Gum Composite

Abstract

In present study, cassava starch (CS) and konjac gum (KGM) were used as the raw materials, and critical melting combined with freeze-thawing (CMFT) was employed as the main treatment for the preparation of CS/KGM composites. The study aimed to investigate the effects of CMFT on the physicochemical and structural properties of CS/KGM composites. The results demonstrated that CMFT effectively facilitated the release of soluble starches, which significantly increased the interaction sites with KGM. The prepared composite had a significantly increased thermal stability (significantly decreased water solubility and swelling power), in which the onset melting temperature of the CS/KGM composite after CMFT was increased significantly from 64.13 ℃ (native) to 69.73 ℃ (0.7% KGM, P<0.05). CMFT significantly improved the pasting properties of the composite, which decreased the breakdown viscosity from 1246.00 (Native) to 949.12 mPa·s (0.7% KGM), and increased the final viscosity from 2182.00 (Native) to 2447.00 mPa·s (0.7% KGM, P<0.05). In addition, CMFT contributed to a significant increase in the relative crystallinity of the composite from 22.19% to 25.50% (P<0.05), indicating the formation of a more compacted internal structure of the composite. The higher addition of KGM further promoted the CS/KGM synergistic effect during CMFT. Overall, the study suggested that CMFT enhanced the synergistic interaction of CS/KGM by partially weakening the granular structure and releasing soluble starches. The prepared composite by CMFT had significantly increased thermal stability and improved pasting properties, which are expected to be used as a functional material in food processing.

Keywords

• cassava starch
• konjac gum
• functional properties
• critical melting
• freeze-thawing