Effect of acidic moisture-conditioning as pretreatment for aqueous extraction of flaxseed oil with lower water consumption

Abstract

Acidic moisture-conditioning plus low temperature drying (AMCLTD) was applied as a pretreatment on flaxseed kernel, for the first time, prior to aqueous extraction (AEP) of flaxseed oil with lower water consumption. Limited information is available on how different pretreatments affect the free oil recovery during AEP. The use of AMCLTD pretreatment with 0.3 M citric acid and drying at 70 °C for 1 h resulted in approximately 83.27 ± 0.67% free oil recovery with thinner cream layer than the sample without pretreatment. Confocal laser scanning microscopy and transmission electron microscopy observations reveal that the coalescence of oil bodies and shrinkage of protein bodies resulted in the decrease of cream and the increase of free oil from AEP. Interestingly, the lowest mean particle size of AMCLTD sample proved that this pretreatment was beneficial to flaxseed comminution. Moreover, the pretreatment showed no significant effect on the fatty acid composition and quality of flaxseed oil. These results demonstrated that AMCLTD pretreatment holds high potential for high-quality flaxseed oil extraction from AEP.