BACKGROUND Triglycerides with varying chain length and unsaturation degree are now in high demand in the food and pharmaceutical industries. Enzymatic catalyzed synthesis methods are favored over chemical-based processes in the commercial production of triglycerides. This study found that the application of vacuum can improve the efficiency and productivity of enzymatic synthesis of various triglycerides using Novozym 435 (EC 3.1.1.3), an immobilized lipase B from Candida antarctica. The system was used for esterification of fatty acids varying in chain length, unsaturation degree, and oxidation degree. RESULTS The vacuum condition was not applicable to short chain fatty acids (C-4-C-6) due to loss of fatty acids in the reaction. The conversions of C-4-C-6 saturated fatty acids were low (15-35%) under atmospheric pressure. Under vacuum, high conversions (>95%) and triglyceride yields (approximately 90%) were achieved in the esterification of glycerol with several medium-chain and long-chain (C-8-C-18) saturated fatty acids. Moreover, unsaturation degree of fatty acids also affected the triglyceride yield. The triglyceride contents synthesized from C18:2n-6 (76.17 +/- 0.45%) was significantly lower (P < 0.05) than those from C18:0 (91.59 +/- 1.58%) and C18:1n-9 (90.77 +/- 0.85%). Furthermore, fatty acids with a high oxidation degree had negative effect on triglyceride synthesis. This vacuum solvent free system allowed the synthesis enzyme to be reused 11 times without significant decrease in the lipase activity for esterification of fatty acids. CONCLUSION The studied vacuum facilitated triglyceride synthesis process provides an economically attractive yet sustainable solution for the production of a wide range of triglyceride products. (c) 2020 Society of Chemical Industry