Preparation of PUFA concentrates as acylglycerols by lipase-mediated hydrolysis of hempseed oil in a continuous flow-reactor

The growing demand for polyunsaturated fatty acid (PUFA) concentrates prompted us to prepare natural glycerides enriched with linoleic acid and alpha-linolenic acid from hempseed oil (Cannabis sativa L.). Seven commercial lipases were screened for the hydrolysis of hempseed oil in a homogeneous medium based on oil and t-BuOH/water. Selectivity showed by lipase from Pseudomonas cepacia for saturated fatty acids (FAs) was exploited to obtain acylglycerols enriched with PUFAs. The enzymatic reaction was scaled up and the acylglycerol components were purified by flash chromatography and analyzed by GC-FID. In the main fraction, containing monoacylglycerols, the amount of PUFAs reached 85% (against 77% of the crude oil) whereas the content of saturated FAs was negligible.1 The omega-6/omega-3 ratio of the monoglyceride component was maintained in the optimal range (4.6:1) for human nutrition. P. cepacia lipase was covalently immobilized and used to set up a continuous flow packed-bed reactor (PBR). The enzymatic hydrolysis of hempseed oil was carried out in a continuous-mode by feeding the reaction mixture upwards the PBR at varying flow rates through a peristaltic pump. The system was coupled in-line with a second glass column filled with an ionic exchange resin to retain hydrolysed free FAs (Scheme), thus allowing the straightforward purification of the glyceride component. The analytical characterization of the purified acylglycerols is in progress.