Optimisation of omega-3 concentration and sensory analysis of chia oil

Abstract

The objective of this study was to obtain concentrated α-linolenic acid ethyl esters from chia oil with values of chemical indicators permitted by current legislation for edible oils and its sensory quality was determined. In the transesterification reaction, sodium hydroxide catalyst concentration and alcohol: oil molar ratios were studied. The model of transesterification with artificial neural networks showed an optimum at a catalyst concentration of 0.387 gNaOH/100goil and a 12.7:1 alcohol: oil molar ratio. The urea complexation was carried out at weight ratios urea: omega-3 fatty acid ethyl esters of 0.5:1, crystallisation at −10 °C for 24 h. Molecular distillation was carried out in one and two stages, where the best results were provided by using one stage, a distillation temperature of 85 °C and pressure of 1.579 × 10−5 atm. The combination of transesterification, urea complexation and molecular distillation allowed obtaining an increase of 24.50 % of omega -3 fatty acids ethyl esters in the final product. This product contains 781.35 g/ kg omega-3, and values of free fatty acids and peroxide of 0.693 % and 1.052 meqO2/kg, respectively. Chia oil presents the higher values of nutty and cream flavour (positive attributes), and turbidity. In the final product these attributes diminishes considerably.