Concentration lauric acid esterification

Enzyme activity was determined as the initial rates in esterification reactions between lauric acid and propanol at a molar ratio of 1 3, a temperature of 60°C, and an enzyme concentration of 5 wt% in relation to the substrates. At the beginning of the reaction, samples containing the mixture of lauric acid and propanol were collected and the lauric acid content was determined by titration with 0.04 N NaOH. After the addition of the enzyme to the substrates, the mixture was kept at 60°C for 15 min. Then, lauric acid consumption was determined. 

The objective of the present work was to study the synthesis of monolaurin by direct lipase-catalyzed esterification between glycerol and lauric acid without any solvent or surfactant. The effects of lauric acid/ glycerol molar ratio, enzyme concentration, and temperature were studied using an experimental design. The reuse of the commercial immobilized lipase, to reduce the process cost, was also investigated. 

Figure 8.7 Concentration and temperature profiles for the esterification of lauric acid with 2-ethylhexanol with an equilibrium-based model. Top Pressure 0.3bar. Seven reactive stages, acid feed on 3 and 5 with 0.5 split, alcohol feed on 7.

Figure 8.15 Dual esterification of lauric acid with methanol and 2-ethyl-hexanol liquid concentration, reaction rate and temperature profiles.

Lipase-catalyzed esterification of fatty acids with alcohols [oleic acid + ethanol (141, 152, 163, 169, 178, 195-197), oleic acid + oleyl alcohol (144, 179, 198-200), lauric acid + butanol (142), myristic acid + ethanol (138, 139, 143, 201), stearic acid + ethanol (202), anhydrous milkfat fatty acids + ethanol (197)] in SCCO2 has been widely studied to understand the kinetics/mechanism of the reaction and to determine the effect of operating conditions, substrate concentration, and water content on enzyme activity. Alternative catalysts such as p-toluenesulfonic... 

Flory [3, 48] found that the esterification reactions between model compounds on the one hand and polyfunctional reactants on the other are substantially identical. Thus the reaction of two monofunctional compounds (lauric acid, lauryl alcohol), of a bifunctional compound with a monofunctional one (adipic acid, lauryl alcohol) and two bifunctional compounds (adipic acid, decamethylene glycol) followed essentially third-order kinetics. In the absence of added strong-acid catalyst a second molecule of the carboxylic acid functions as catalyst. Thus when the concentrations (C) of the reacting groups are identical, the rate is given by ... 

FIGURE 13.4 Dependence of the initial velocity Vq of the esterification reaction of lauric acid with hexanol ( ) and decanol (O) catalyzed by P. simplicissimum lipase in AOT/ isooctane microemulsion, as a function of the alcohol concentration. (From Stamatis, H. Enzymatic conversion of amphiphilic substrates in microemulsions, PhD thesis, University of Patras, Patras, 1996). 

Borage oil (22% GLA) is hydrolysed completely Pseudomonas species, 35°C, 24 h) and the borage acids are selectively esterified with lauric alcohol in the presence of Rhizopus delemar lipase at 30 C for 20 h. The latter enzyme discriminates against GLA and this concentrates in the unesterified acids fraction, which finally contains 70% GLA (74% recovery). If the esterification is repeated (using Candida rugosa lipase, 35 C, 15 h), 94% GLA is obtained with 68% recovery (Shimada et al 1997). 

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