Effects of Refining on Konjac Glucomannan and Gel Properties of Its Blend with κ-Carrageenan

Refined conditions of konjac glucomannan (KGM), physicochemical properties and structural characterization of KGM before and after refining and its blend with κ-carrageenan were explored in this study. Furthermore, the correlation between physicochemical properties of KGM and gel properties of the blend was also determined. The result showed that refined conditions of KGM were as follows: Refined ethanol concentration 60%, swelling time 2 h, swelling temperature 50 ℃. With this treatment, the glucomannan content, viscosity, brightness and whiteness of KGM were increased by 34.43%, 128.55%, 17.94% and 28.29%, respectively. Gel strength, hardness, chewiness and gumminess of its blend with κ-carrageenan were significantly increased by 47.39%, 60.47%, 55.44%, and 45.87%（P < 0.05）, respectively. The best gel properties of the blend were obtained with the enhanced hydrogen bond force, smoother and tighter gel network structure. In addition, physicochemical properties of KGM e.g. glucomannan content, viscosity, color and flavor were considered to be the key factors to improve quality of the blend gel. This study could provide an efficient and simple refined method for development of KGM and carrageenan blend with high gel strength, and lay a theoretical foundation for the industrial production of refined KGM in future.