title: Low intensity ultrasound as a pretreatment to drying of daylilies: Impact on enzyme inactivation, color changes and nutrition quality parameters.
abstract: 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/cm2) 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.
authors.affiliation: Institute of Farm Product Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
authors.forename: Zhongyuan
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Institute of Farm Product Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
authors.forename: Liying
authors.initials: L
authors.lastname: Niu
authors.affiliation: Institute of Farm Product Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China. Electronic address: lidajing@163.com.
authors.forename: Dajing
authors.initials: D
authors.lastname: Li
authors.affiliation: Institute of Farm Product Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
authors.forename: Chunquan
authors.initials: C
authors.lastname: Liu
authors.affiliation: Institute of Farm Product Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; College of Forestry, Northeast Forestry University, Harbin 150040, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Ma
authors.affiliation: Institute of Farm Product Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
authors.forename: Jiangfeng
authors.initials: J
authors.lastname: Song
authors.affiliation: Institute of Farm Product Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
authors.forename: Jiangtao
authors.initials: J
authors.lastname: Zhao
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D002338:Carotenoids / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D003890:Desiccation; D004789:Enzyme Activation; D031421:Hemerocallis / Q000201:enzymology / Q000378:metabolism*; D006358:Hot Temperature; D007700:Kinetics; D010088:Oxidoreductases / Q000378:metabolism*; D010858:Pigmentation; D000069453:Ultrasonic Waves
chemical_list: D000975:Antioxidants; D002734:Chlorophyll; D002338:Carotenoids; D010088:Oxidoreductases
keywords: Anti-oxidant activity; Browning; Daylilies; Enzyme inactivation; Low intensity ultrasound