title: Effect of high-intensity ultrasound on the physicochemical properties and nanostructure of citrus pectin.
abstract: BACKGROUND
  Modified pectin has been found to have various biological activities. The preparation of modified pectin is generally accomplished by either chemical or enzymatic depolymerisation processes, but both methods have several disadvantages. Ultrasound treatment is simple and requires shorter times and lower temperatures than conventional techniques used for processing plant materials. In recent years the application of ultrasound to modify polysaccharides has received increasing attention. The objective of this study was to use ultrasound to modify citrus pectin.
  
  
  RESULTS
  The average molecular weight of citrus pectin decreased under different ultrasonic conditions. The average molecular weight decreased from 464 to 296 kDa after 30 min of sonication. The degree of methylation of citrus pectin changed slightly and its monosaccharide component remained unchanged when high-intensity ultrasound was applied. The reduced (Gal+Ara)/Rha ratio after ultrasonication suggested degradation in the neutral sugar side chains of citrus pectin. Atomic force microscopy results confirmed the degradation of citrus pectin chains by ultrasound at nanolevel.
  
  
  CONCLUSIONS
  Ultrasound is an effective way to pretreat or modify pectin. The degradation of citrus pectin is due to the cavitational effects of ultrasound. Thus ultrasound may be useful in establishing environmentally friendly extraction and modification technologies for pectin.
authors.affiliation: College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, Zhejiang, China.
authors.forename: Lifen
authors.initials: L
authors.lastname: Zhang
authors.forename: Xingqian
authors.initials: X
authors.lastname: Ye
authors.forename: Sophia Jun
authors.initials: SJ
authors.lastname: Xue
authors.forename: Xianzhong
authors.initials: X
authors.lastname: Zhang
authors.forename: Donghong
authors.initials: D
authors.lastname: Liu
authors.forename: Ruifeng
authors.initials: R
authors.lastname: Meng
authors.forename: Shiguo
authors.initials: S
authors.lastname: Chen
mesh_terms: D055598:Chemical Phenomena; D002957:Citrus / Q000737:chemistry*; D010368:Pectins / Q000737:chemistry*; D014465:Ultrasonics
chemical_list: D010368:Pectins