Optimization of hemp seeds (Canapa Sativa L.) oil mechanical extraction

The interest in hemp (Canapa Sativa L.) in the last decade is greatly increased for its multiplicity of uses: food; textile industry; cosmetics and biochemical. In addition, hemp seed oil is a great source of high quality nutrients and has multi-purpose natural remedies and It could be used as edible oil containing about 80% of essential fatty acids (excellent ratio of omega-6 to omega-3). The aim of this study was the optimization of hemp seeds oil mechanical extraction parameters in order to have a higher oil yield. The hemp variety was Futura 75, cultivated in Castelvolturno (CE), Southern Italy. Harvest has been carried out in September 2016 with a mechanical harvester. The test has been carried out using a mechanical screw press, powered by 2.2 kW electric motor, using an 8 mm nozzle. The variable parameters were: temperature of extraction (50°C and 70°C), measured with a temperature sensor placed on press head; two rotational screw speeds (22 rpm and 32 rpm) and seeds pre-treatment (heated at 50°C for 1h in a laboratory oven and not heated). The processed samples weighted 1000g each. After the extraction, oil was centrifuged at 3500 rpm for 20 minutes with an laboratory centrifuge to determine the yield of pure oil as percentage of extracted oil (g) on the total oil extractable basis. During the tests, the performances of the press has been monitored: initial and final extraction temperatures have been recorded with a RTD (Pt100) temperature sensor; extraction time has been recorded with a laboratory stopwatch. Results show that the combination of high extraction temperature and slow rotational screw speed has a positive effect on oil yield as well as seeds pre-treatment. Further studies are scheduled in order to evaluate the effect of extraction parameters on oil quality in terms of acidity, sensory profile, volatile compounds and fatty acids composition.