Enzymatic esterification
To optimize the esterification conditions of PAs (CA, FA orp -HCA) with glycerol, CA was used as the material in the model of the reaction. The enzymatic esterification of 0.25 mmol CA with different mole of glycerol (12.5-37.5 mmol) was carried out in a 10 mL schlenk flask. Reaction mixtures were incubated at various temperatures (70-90 oC) using heating block with a magnetic stirrer at 500 rpm under 86.7 kpa. Then a certain amount of lipase (3-30 % of the total weight of the substrates) was added to the reaction mixture. At regular time intervals, samples (20 μL) were withdrawn and diluted in 980 μL of mobile phase for quantitative analysis using HPLC as described in Section 2.3.