BACKGROUND: Eutectic solvents are a mixture of two compounds which possess a lower melting temperature than compounds by themselves at low temperatures (below 100ºC), using quaternary ammonium salts, as choline and betaine, and organic acids, polyols and amides as hydrogen bond donors. These solvents can be an alternative as non-aqueous media for enzymatic reactions, mainly using lipases. The objective of this work is to evaluate enzymatic activity and stability of commercial lipases), immobilized or at free form (Thermomyces lanuginosus: Lipozyme TL IM, iTL and Lipolase 100 L, fTL; Candida antarctica: Novozym 435, iCALB; Novozym 735, iCALA and Novozym CALB L, fCALB; and a phospholipase (Lecitase Ultra), in the presence of eutectic solvents (choline chloride (ChCl):urea, ChCl:glycerol, betaine hydrochloride (BeHCl):urea and BeHCl:glycerol.
METHODS: Initially, lipases were maintained by 2 hours at solutions of choline and betaine-based eutectic solvents (1 to 20% m/m) at 25ºC, comparing with water as relative enzymatic activity. Using the solvent that best promoted lipasic activity, some parameters were evaluated as molar ratio between quaternary ammonium salts and urea, stocking temperature and kinetics.
RESULTS AND CONCLUSION: These eutectic solvents enable, mainly with immobilized lipases, 25 to 125 times more activity than water at 25ºC and 2h, and even after 24h, lipase iTLL was still 40 times more active in the presence of ChCl:Urea 1:3. Lipase iCALB showed great thermostability 47 times higher at 55ºC, almost doubling relative activity at 25ºC in the presence of BetHCl:Urea 1:4.