Effects of water-soluble secondary antioxidants on the retention of carotene and tocols during hydrolysis of crude palm oil catalysed by Eversa® Transform 2.0 for alcohol-free production of palm phytonutrients concentrate

Abstract

The liquid lipase Eversa® Transform 2.0 (ET 2.0) was used to catalyse the hydrolysis of crude palm oil (CPO) to concentrate and extract carotene and tocols, which is then followed by separation. Nonetheless, the production of free fatty acids (FFA) promotes auto-oxidation, resulting in significant loss of the palm carotenes and tocols during hydrolysis. Therefore, this study explores the effects of incorporating several secondary acid antioxidants namely ascorbic acid, citric acid and ethylenediaminetetraacetic acid (EDTA), on the production of FFA and retention of palm phytonutrients during the enzymatic hydrolysis of CPO. Generally, the results revealed that the addition of these secondary antioxidants notably enhanced the retention of the palm phytonutrients. However, citric acid at high concentrations were found to impose a negative effect on the production of FFA, primarily due to the acid denaturation of the lipase after at low pH conditions. It can be concluded that EDTA is the best performing antioxidant as it efficiently retained 98% of the palm carotene and 97% of the tocols after 24 h of reaction without disrupting the FFA production, remarkably at much lower concentrations (0.01 wt%) in comparison to the other antioxidants. It was deduced that the reason for this is mainly its low solubility in both oil and water phases of the reaction. Finally, separation of the FFA from the oil using vacuum distillation at 200 ℃ and 100 Pa for 1 h successfully enriched the palm carotene and tocols by 2.7-fold and 8.8-fold, respectively.