Effects of Different Blanching Methods on Nutritional and Sensory Quality of Jingcai Sweet Corn

In this study, Jingcai sweet corn was used as raw material. The effects of steam blanching and water bath blanching on the heat transfer rate, nutrient content, enzyme activity, colour change, texture profile analysis and sensory quality of Jingcai sweet maize were investigated at temperatures of 85, 90 and 95 ℃ for 0, 5, 10, 15 and 20 min, respectively. The results showed that steam blanching was superior to water bath blanching in terms of retaining nutritional qualities. It allowed the internal temperature of the maize to rise rapidly and reduce the loss of nutrients. The data showed that the heat transfer rate of the steam blanching treatment group were 19.70%, 15.31% and 15.90% higher than that of the water bath blanching when the blanching temperature were 85, 90 and 95 ℃ respectively. In terms of soluble sugar content, the retention rates were 71.11%, 70.67% and 70.11% for the steam blanching treatment group and 64.44%, 62.33% and 58.89% for the water bath blanching treatment group, respectively. Furthermore, for the vitamin C content, the retention rates were 56.67%, 54.17% and 51.67% for the steam blanching treatment group, compared to 53.33%, 50.00% and 44.17% for the water bath blanching treatment group, respectively. Further comparison of blanching temperature and time effects showed that with the treatment of 95 ℃ for 10 min, peroxidase and polyphenol oxidase activities could be effectively inactivated. Meanwhile, the color of Jingcai sweet corn was desirable, the L^* and b^* values were 84.62 and 33.30, respectively. The hardness, springiness and chewiness in texture profile analysis were 28.03 N, 3.29 mm and 16.88 mJ, respectively, and its sensory score was 93. It was concluded that steam blanching at 95 ℃ for 10 min was the most suitable method for the post-harvest blanching of Jingcai sweet maize, which would provide a theoretical reference for the post-harvest blanching process of Jingcai sweet corn.