title: Effect of ultrasound on enzymatic acylation of konjac glucomannan.
abstract: A comparative study was made of enzymatic acylation of konjac glucomannan with vinyl esters under ultrasonic irradiation and shaking in organic solvent tert-butanol. Among the 13 enzymes selected, Novozym 435 exhibited the highest acylation activity towards KGM whether under ultrasonic irradiation or shaking. The application of ultrasonic irradiation instead of shaking during the acylation led to improvement in the initial reaction rate, yield and degree of substitution of the modified KGM. Appropriate ultrasound power (100 W) and water activity (0.75) were found to accelerate enzymatic reaction. The acceleration effect of ultrasound on Novozym 435-catalyzed acylation decreased with an increase in the chain length of the acyl donors from C2 to C18. Moreover, the acylation of KGM in tert-butanol was proved to be a regioselective one, with C6-OH being acylated. Compared with shaking, ultrasound did not change regioselectivity of Novozym 435 in the acylation.
authors.affiliation: College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China. zgchen@njau.edu.cn
authors.forename: Zhi-Gang
authors.initials: ZG
authors.lastname: Chen
authors.forename: Min-Hua
authors.initials: MH
authors.lastname: Zong
authors.forename: Zhen-Xin
authors.initials: ZX
authors.lastname: Gu
authors.forename: Yong-Bin
authors.initials: YB
authors.lastname: Han
mesh_terms: D000215:Acylation; D004789:Enzyme Activation / Q000528:radiation effects; D004795:Enzyme Stability / Q000528:radiation effects; D008351:Mannans / Q000737:chemistry* / Q000528:radiation effects*; D011829:Radiation Dosage; D013010:Sonication; D020002:tert-Butyl Alcohol / Q000737:chemistry*
chemical_list: D008351:Mannans; C022901:(1-6)-alpha-glucomannan; D020002:tert-Butyl Alcohol