title: Lipase immobilization on hyper-cross-linked polymer-coated silica for biocatalytic synthesis of phytosterol esters with controllable fatty acid composition.
abstract: In this study, a novel mixed-mode composite material, SiO(2)@P(MAA-co-VBC-co-DVB), was prepared via the hyper-cross-linking of its precursor, which was produced via suspension polymerization in the presence of SiO(2) particles.  Candida rugosa  lipase (CRL) was immobilized on the SiO(2)@P(MAA-co-VBC-co-DVB) particles via hydrophobic and weak cation-exchange interaction. The resulting immobilized CRL showed much better thermal stability and reusability in comparison to free CRL. On the basis of the excellent biocatalyst prepared, a method for high-efficiency enzymatic esterification of phytosterols with different fatty acids to produce the corresponding phytosterol esters was developed. Six phytosterol esters with conversions above 92.1% and controllable fatty acid composition were obtained under the optimized conditions: 80 μmol/mL phytosterols, 160 μmol/mL linolenic acid, and 15 mg/mL CRL@HPCS at 300 rpm and 50 °C for 7 h in 30 mL of isooctane. The prepared phytosterol esters possessed a low acid value (≤0.86 mg of KOH/g), peroxide value (≤3.3 mequiv/kg), and conjugated diene value (≤1.74 mmol/kg) and high purity (≥97.8%) and fatty solubility (≥28.9 g/100 mL). All the characteristics favored the wide application of phytosterol esters with controllable fatty acid composition in different fields of functional food.
authors.affiliation: Hubei Key Laboratory of Oilcrops Lipid Chemistry and Nutrition and Key Laboratory of Oil Crops Biology of the Ministry of Agriculture, Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan 430062, China.
authors.forename: Ming-Ming
authors.initials: MM
authors.lastname: Zheng
authors.forename: Yong
authors.initials: Y
authors.lastname: Lu
authors.forename: Feng-Hong
authors.initials: FH
authors.lastname: Huang
authors.forename: Lian
authors.initials: L
authors.lastname: Wang
authors.forename: Ping-Mei
authors.initials: PM
authors.lastname: Guo
authors.forename: Yu-Qi
authors.initials: YQ
authors.lastname: Feng
authors.forename: Qian-Chun
authors.initials: QC
authors.lastname: Deng
mesh_terms: D055162:Biocatalysis; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000378:metabolism*; D004951:Esterification; D005227:Fatty Acids / Q000032:analysis*; D008049:Lipase / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D010840:Phytosterols / Q000096:biosynthesis* / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D005227:Fatty Acids; D010840:Phytosterols; D011108:Polymers; D012822:Silicon Dioxide; D008049:Lipase