Molecular distillation and characterization of diacylglycerol‐enriched palm olein

Abstract

Lipase‐catalyzed glycerolysis of palm olein was used to produce a mixture of acylglycerols with ∼34‐wt% of DAG. The reaction conditions were 5‐wt% of Lipozyme TLIM at 55°C and 8 h of reaction time. For commercial purposes, it is required to purify the product up to 80‐wt% DAG and with free fatty acids (FFA) content below 0.1‐wt%. A single‐step distillation process was not sufficient to meet this product requirement. Two distinct 2‐step short path distillation approaches were then studied. First scheme involved the removal of TAG by initial distillation step at 250°C, followed by separation of the MAG and FFA from distillate obtained at 180°C during second distillation step at vacuum pressure of 0.1 Pa. Second scheme involved the removal of MAG and FFA in first step at 180°C prior to purification of DAG from residue at 250°C during second distillation step at vacuum achieved up to 0.1 Pa. The results suggested that the first scheme of 2‐step distillation operation was able to achieve 89.9‐wt% of DAG purity without exceeding the limit of 0.1‐wt% of FFA. A final yield of 21.5‐wt% and DAG recovery of 47.8% were obtained using the first scheme. A detailed DAG profile was identified and product characterizations such as fatty acid composition, slip melting point, and solid fat content profile were also investigated. It was observed that purified‐DAG product showed lower iodine value and higher slip melting point than raw material palm olein. The final product had 1134 ± 10 ppm tocols content.Practical applications: This paper has two main practical applications: (i) Enables production of highly purified DAG‐based palm olein via appropriate processing method and processing conditions. (ii) Provide knowledge and understanding of the physicochemical properties of DAG‐enriched palm olein fraction, which is a crucial aspect in food applications.The purpose of this study was to develop an effective distillation process for purification of diacylglycerol (DAG)‐oil. Two distinct 2‐stage short path distillation approaches were proposed and evaluated for their efficacy of operations. It was concluded that first scheme, which involved the removal of TAG in the first distillation stage at 250°C, followed by separation of the MAG and free fatty acid (FFA) from distillate at 180°C in second distillation step, was able to meet product specifications with more than 80‐wt% of DAG purity without exceeding the limit of 0.1‐wt% FFA.