Ethyl stearate is an ester obtained by the esterification of stearic acid and ethanol. Esters are organic substances that can be found in nature and it is of great importance pharmaceutical industry, perfumes, polymers, cosmetics and in the food industry. Ethyl stearate is widely used in the perfume industry in fragrances in small concentrations, and can also be used as artificial flavoring, generally as additives to enhance the aroma of a drink or a food. This study aimed to evaluate the enzymatic synthesis of ethyl stearate in a free-solvent system. For the synthesis the effect of the agitation of 150 at 250 rpm and molar ratio between the substrates of 1:1 at 1:7 (acid:alcohol) was evaluated since the temperature (60 °C) and enzyme concentration (1%, wt of acid) were kept constant. Commercial ipases Novozym 435 and NS 88011 were tested and Novozym 435 showed better performance (82% conversion) for the synthesis of ethyl stearate. The highest conversion (92%) in ethyl stearate in the optimized condition was obtained at molar ratio of 1:5, 60 °C, 200 rpm of agitation, enzyme concentration of 1 wt%, 24 h of reaction and addition of alcohol fractionated in three portions in the first hours of reaction. This study also evaluated the possibility of reuse of the biocatalyst, obtaining satisfactory results of 60% in three cycles.
Enzymatic esterification of stearic acid and ethanol for ethyl stearate production
Pier Paolo Giovannini;Lindomar A. Lerin
2018
Abstract
Ethyl stearate is an ester obtained by the esterification of stearic acid and ethanol. Esters are organic substances that can be found in nature and it is of great importance pharmaceutical industry, perfumes, polymers, cosmetics and in the food industry. Ethyl stearate is widely used in the perfume industry in fragrances in small concentrations, and can also be used as artificial flavoring, generally as additives to enhance the aroma of a drink or a food. This study aimed to evaluate the enzymatic synthesis of ethyl stearate in a free-solvent system. For the synthesis the effect of the agitation of 150 at 250 rpm and molar ratio between the substrates of 1:1 at 1:7 (acid:alcohol) was evaluated since the temperature (60 °C) and enzyme concentration (1%, wt of acid) were kept constant. Commercial ipases Novozym 435 and NS 88011 were tested and Novozym 435 showed better performance (82% conversion) for the synthesis of ethyl stearate. The highest conversion (92%) in ethyl stearate in the optimized condition was obtained at molar ratio of 1:5, 60 °C, 200 rpm of agitation, enzyme concentration of 1 wt%, 24 h of reaction and addition of alcohol fractionated in three portions in the first hours of reaction. This study also evaluated the possibility of reuse of the biocatalyst, obtaining satisfactory results of 60% in three cycles.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
