To solve the problem of the degradation of the texture properties of frozen konjac glucomannan (KGM) gels after thawing, this study used six thawing methods, including 4 ℃ refrigerator, 25 ℃ air, 25 ℃ water immersion, 40 ℃ water immersion, microwave, and ultrasonic to thaw the frozen KGM gels and to determine the changes of the gel properties and structure after thawing. Results showed that the thawing time of the 4 ℃ refrigerator was the longest, and the whiteness of the thawed KGM gels decreased by 2.96% compared with 25 ℃ air, but the syneresis rate was the lowest. 25 ℃ and 40 ℃ water immersion thawing time was shorter compared with 25 ℃ air, but the gel network structure of 40 ℃ thawing was severely damaged by syneresis, and the syneresis rate increased by 16.48%. The microwave thawing time and gel whiteness decreased by 99.71% and 0.75%, respectively, compared to 25 ℃ air. Ultrasonic thawing of KGM gels showed better whiteness, hardness, viscosity, and chewiness, with 4.68%, 66.05%, 74.44%, and 75.61% improvement compared with 25 ℃ air, respectively, and its syneresis rate decreased by 19.56%, with more uniform dense and smaller pore size gel network structure. Microwave and ultrasonic thawing slightly enhanced the hydrogen bonding in the KGM gel system, while 4 ℃ refrigerator thawing slightly reduced the crystallinity of frozen KGM gels, but the different thawing treatments did not affect the chemical backbone structure, deacetylation behavior, and crystalline morphology of KGM. Ultrasonic thawing is efficient and effective in maintaining the quality of KGM gels after thawing. The results of this study may provide theoretical guidance for the production of KGM gel food.
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