Institute of Farm Product Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
Institute of Farm Product Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
Ultrason Sonochem. 2017 May;36:50-58. doi: 10.1016/j.ultsonch.2016.11.007. Epub 2016 Nov 5.
Effects of thermal and low intensity ultrasound combined with heat (LIUH) pretreatment prior to microwave vacuum drying on enzyme inactivation, color changes and nutrition quality properties of dried daylilies were investigated. The peroxidase (POD), ascorbic acid oxidase (AAO) and polyphenoloxidase (PPO) thermal and LIUH (0.2 and 0.4W/cm) inactivation were determined and compared at 70, 80 and 90°C. Significant reduction in the POD, AAO and PPO activity was seen in daylilies after an ambient LIUH pretreatment than thermal pretreatment. POD, AAO and PPO thermal and LIUH inactivation followed the first order kinetics. LIUH pretreatment had a more positive influence on maintaining color of dried daylilies than thermal pretreatment. Furthermore, LIUH pretreatment resulted in a significant increase in chlorophylls, carotenoids (lutein, zeaxanthin and β-carotene), and a decrease in degree of browning and 5-hydroxymethylfurfural (HMF) when compared with thermal pretreatment. The antioxidant activity and contents of several nutritional components of dried daylilies pretreated by LIUH were also higher than that of dried daylilies pretreated by thermal pretreatment. This study provides a basis for the design of LIUH conditions to control vegetables browning and color changes prior to drying processing.
研究了微波真空干燥前热和低强度超声联合加热（LIUH）预处理对干黄花菜酶失活、颜色变化和营养品质特性的影响。测定并比较了 70、80 和 90°C 下，过氧化物酶（POD）、抗坏血酸氧化酶（AAO）和多酚氧化酶（PPO）的热和 LIUH（0.2 和 0.4W/cm）失活动力学。与热预处理相比，环境 LIUH 预处理后黄花菜中 POD、AAO 和 PPO 的活性明显降低。POD、AAO 和 PPO 的热和 LIUH 失活均遵循一级动力学。LIUH 预处理对保持干黄花菜颜色的影响比热预处理更为积极。此外，与热预处理相比，LIUH 预处理可显著增加叶绿素、类胡萝卜素（叶黄素、玉米黄质和β-胡萝卜素）含量，降低褐变程度和 5-羟甲基糠醛（HMF）含量。LIUH 预处理的干黄花菜的抗氧化活性和几种营养成分含量也高于热预处理的干黄花菜。本研究为设计 LIUH 条件以控制蔬菜干燥加工前的褐变和颜色变化提供了依据。
