Phospholipid-stabilised water-in-oil microemulsions: A study of ester synthesis by Humicola lanuginosa lipase

摘要: In a model reaction, octyl decanoate was synthesised from n-octanol and decanoic acid using Humicola lanuginosa lipase entrapped in hydrated lecithin reversed micelles n-heptane. The surfactants used were pure phosphatidylcholine (PC) egg yolk, partially purified preparation dried yolk (EY-PC) containing about 60% PC, two soybean (SB-PC), one 40% PC the other 48% PC. Reaction took place readily all systems. initial rate of reaction different phospholipid systems compared to similar system stabilised by sodium bis (2-ethylhexyl) sulphosuccinate (AOT) superior every case. ester formation higher phosphatidylcholine. For 700 mM water, phase separation into an emulsion occurred at concentration around 75 substrte concentrations 100 mM. contrast, preparations stable microemulsions equilibrium (about 95% conversion). effects enzyme concentration, water activity, surfactant substrate temperature studied lecithin. proportional broadly independent concentration. Esterification activity tended zero very low (aw) content. Maximal esterification expressed above ω0 ≈ 10 (ω0 = [water][PC]) where aw≈0.8. An apparent activation energy 20 ± 2 kJ mol−1 determined over range 10–60°C, which is consistent with previous determinations for lipases obtained alternative microemulsion synthetic such as AOT.