Yishun Yao,Xunjiao Wei,Huiyun Pang,Ke Wang,Qiang Liu,Hongfei Fu,Xiangwei Chen,Yunyang Wang
This paper investigated the effects of radio-frequency (RF) energy and conventional hot-water blanching (95 °C for 2 min) on the peroxidase (POD) activity, physiochemical properties, and changes in the cellular morphology of stem lettuce. The relative residual POD activity significantly decreased ( P < 0.05) from 66.03% to 6.46% with increased RF heating temperature (65 °C–85 °C). The weight loss (3.06%–7.64%), color, texture, relative electrolyte leakage (23.45%–67.90%), and residual vitamin C content (72.22%–16.67%) significantly changed ( P < 0.05) with increased RF heating temperature (65 °C–85 °C). Micrographs indicated that the changes in physiochemical property can be attributed to the destruction of cell membranes, loss of cell turgor, reduced rigidity of cell walls, and loose adhesion between adjacent cells. Samples treated by RF heating at 75 °C showed lesser cell damage and better nutrient retention than those treated by hot-water blanching at a similar level of POD inactivation.
Jun Wang,Yuxian Chen,Hui Wang,Shuyao Wang,Zina Lin,Lili Zhao,Huaide Xu
The impacts of ethanol pretreatment and blanching on moisture transfer, microstructure, and nanostructure of cell-wall polysaccharides of apple slices were studied. The physicochemical properties, namely, color, rehydration, and antioxidant capacity were also evaluated. The results corroborated that the use of ethanol and blanching reduced drying time 45–60% and 21–42% at various drying temperatures (50, 60, 70, and 80 °C), respectively, compared to controls. Ethanol loosened the cell wall structure, thereby reducing the internal resistance of moisture diffusion, and the changes in cell wall structure caused by blanching were mainly due to the β-elimination degradation of pectins. Both samples of ethanol pretreatment and blanching possessed lower browning index and higher antioxidant capacity compared with the untreated ones. Overall, ethanol pretreated products exhibited the shortest drying time, less color change and higher antioxidant capacity. These results provide new insights on possible mechanisms about ethanol pretreatment and blanching to improve drying.
危险品化学品经营许可证（带存储）