ENZYME-ENGINEERING, MEDIUM-ENGINEERING, AND REACTION-ENGINEERING TO DESIGN A LOW-COST, SELECTIVE PRODUCTION METHOD FOR MONOOLEOYLGLYCEROLS AND DIOLEOYLGLYCEROLS

The selective enzymic production of mono- and diolein (MO, DO) was opt imized at high yields. A comparative study of the following distinct e nzymic reactions was conducted: ethyl oleate glycerolysis, triolein (T O) glycerolysis, and direct esterification. Solvent-free systems were compared with media that contained different solvents. Native, modifie d (with polyethylene glycol), and immobilized lipases were used. Mecha nical resistance, the support effect on enzyme and glycerol dispersion and on process reproducibility, and hydrophilicity of the support wer e considered in the process optimization. We report the use of an immo bilized lipase on an inorganic support (Celite), which has high activi ties in both solid-phase glycerolysis (99% reaction conversion) and es terification (100% conversion). The optimum conditions for the distinc t reactions were compared by considering their selectivities, conversi ons, yields, and cost of the substrates. We found less costly and more selective processes in the absence of solvents for glycerolysis of tr iolein and direct esterification. Although glycerolysis was the most i nteresting process to produce diolein, esterification was better for m onoolein preparation with this biocatalyst. The esterification reactio n yielded 93 wt% of MO, in the absence of either TO or oleic acid (OA) , at low cost because of the 100% reaction conversion. Similar costs o f the substrates (10.6 and 10.1 $/g) were necessary to obtain 67 and 8 0 wt% of DO in esterification and glycerolysis, respectively. The glyc erolysis conversion was 96%. In esterification, the product mixture wa s impure, with a high amount of residual OA due to the low conversion (59%). The high activity of PSL-Celite in these solid-phase reactions has an advantage over the reactions with non immobilized-lipases due t o the ease of enzyme recovery. The absence of organic solvents reduces the need for solvent removal from the reaction mixtures.