Feasibility on the Use of Acid Value for Evidencing the Esterification of Glycerol with Caprylic Acid Catalyzed by Lipase

The present paper deals with the use of Acid Value (AV), a titration method largely used for fatty acid quantification, to determine the acidity of products resulting from caprylic acid (CA) and excess glycerol (GLY) esterification catalyzed by an immobilized lipase, aiming to obtain caprylins (CL), as well as the blends of these two components (GLY/CA) in different proportions used as substrate for the reactions. Response surface methodology (RSM) was used to determine the effects of three variables (temperature, reaction time, and GLY/CA molar ratio) on the caprylin production optimization. The AV of the blends decreased with an increasing molar ratio GLY/CA and a coefficient variation of 11% for the AV method was obtained. The RSM did not provide a clear statistical correlation between AV and the reaction parameters selected as variables. However, among all obtained AV values, 77% were in the range between 50 and 100 mg NaOH/g, including the experiment performed under the conditions of 60oC, 8h, and GLY/CA molar ratio of 2, in which the highest caprylin production yield of about 50% was obtained.