A New Deacidification Strategy for Crude Vegetable Oil：Removal of Free Fatty Acids via Photobiocatalytic Decarboxylation

Crude vegetable oils can contain sometimes high concentrations of free fatty acids (FFAs) forming during manufacture, processing, transportation and storage. As FFAs may impair the senoric and olfactory properties of vegetable oil products, efficient deacidification strategies for crude vegetable oils are highly desirable. In this work, crude vegetable oils were deacidified by using a recently discovered photodecarboxylase from Chlorella variabilis NC64A (CvFAP) heterologously expressed in Escherichia coli catalyzing selective decarboxylation of FFAs while leaving esters unmodified. Using this novel approach, deacidification degree of 8 different crude vegetable oils with varying initial FFAs content (1.62%–39.68%) reached 83.17%–98.30% after 6 h at 30 ℃. The highest degree of deacidification (99.33% after 6 h) was achieved for crude rice bran oil with 13.98% initial FFAs under optimized conditions. The deacidification reaction was negatively affected by increasing crude vegetable oil concentration, which was probably due to low value of solvent accessible surface area when surrounded by high mole of FFAs. This study developed mild reaction conditions and simple deacidification making the production process of crude vegetable oils environmentally friendly.