Quality evaluation of rapeseed oils used as engine fuels

Samples from six reference decentralised facilities and one industrial production unit of rapeseed oils were taken for the evaluation of the influence of production processes to the properties specified in the technical standard; in the laboratories, the properties limited by the standard for rapeseed oils were determined. In addition, long-term monitoring of changes in the oxidation stability in the storage test of rapeseed oils additived in the quantities of 200, 400 and 600 mg/kg of the Baynox antioxidant was started. The results confirmed that the critical points in the rapeseed oil production process consist in the contamination with ash-forming elements, such as phosphorus, magnesium, calcium and overall impurities. Not only in the case of hot pressing, but also in two-step cold pressing of rapeseed it is necessary to reduce the content of ash-forming elements using additional processes, such as degumming, neutralisation and whitening. The safety step consisting of filtration down to maximum particle size of 1 microm must be always in place before the oil distribution. A positive effect of the Baynox antioxidant was clearly proved. As 200 mg/kg of Baynox was added, the oxidation stability value increased from 8 to 9.05 hrs immediately after the pressing with a consequent decrease to 6 hrs after 270 days. When using 400 ppm Baynox the oxidation stability decreased under 6 hours not until after 390 days of storage. When adding 600 ppm Baynox the oxidation stability of rapeseed oil was 6.5 hours even after 510 days of storage. The quality monitoring brought about necessary findings and knowledge for the optimisation of the rapeseed oil production and distribution as engine fuels. In addition, it serves as an initial supporting document for the creation of the necessary quality control system.