The effect of citric-acid treatment on the physicochemical and gel properties of konjac glucomannan from Amorphophallus bulbifer

The Amorphophallus bulbifer (A. bulbifer) as a newly developed superior konjac variety has the advantages of short growth cycle, high reproductive coefficient, disease resistance and adaptation to humid or hot environments. Because of its good growth characteristics and high konjac glucomannan (KGM) content, A. bulbifer has great potential to be used as KGM resources in food industry. However, KGM from the A. bulbifer flour has very high viscosity even in low concentration, and the gels formed by KGM are easily browning during the alkali-induced process. These shortcomings are key factors that limit its application in the food industry. In order to solve this problem, KGM was modified by citric-acid treatment (CAT), and the effect of CAT on the physicochemical and gel properties of KGM was investigated in this study. The results indicated that the apparent viscosity and ΔE value of the KGM treated with 1.2 M CAT for 2 h were 948.66 Pa·s and 14.55, respectively, which were significantly lower than native KGM in the same variety. Moreover, the CAT did not significantly affect the texture properties of KGM gels. Hence, it will be extremely valuable for developing innovative low-calorie foods favored by consumers and industrial production based on KGM.