Influence of industrial physical refining on tocopherol, chlorophyll and beta‐carotene content in sunflower and rapeseed oil

Abstract

The main purpose of this article was to investigate the influence of individual processes in physical refining on tocopherol content in sunflower and rapeseed oils. During refining some chemical parameters, the oxidative stability of oils and some minor compounds such as chlorophyll and beta‐carotene, were determined. Those analytical data with explained chemical backgrounds gave more qualitative overview of what happened to the same lot of oils being processed in a continuous operation. Some processes were compared with a laboratory oil refining. Crude rapeseed oil contained 656 mg/kg of total tocopherols, followed by high oleic sunflower with 373 mg/kg of tocopherols and classic sunflower oil with 332 mg/kg of tocopherols. The most serious refining processes were bleaching and physical deodorization process, the tocopherol losses being 14.9–17.4% and 20.2–27.1%, respectively. In the refined oils, chlorophylls and FFAs were almost completely removed and the oxidative stability increased 2–3 times. Vegetable oil refining process caused relatively great losses of minor compounds but this, in turn, prolonged the shelf life of edible oils.Practical applications: It was proved that refining of sunflower and rapeseed oils in the oil refinery improves their basic chemical parameters. The loss of tocopherols can be minimized by shortening the time and lowering the temperature during the final step of physical refining, but it has to remain within requirements on quality of refined edible oils.The refining processes of sunflower and rapeseed oils lead to 39.0–45.5 % loss of total tocopherol content. The most serious refining processes were bleaching and physical deodorization process, the tocopherol losses being 14.9–17.4 % and 20.2–27.1 %, respectively. Degumming process can caused 6.6–8.4 % decrease of tocopherols in sunflower and rapeseed oil. Most gentle process was winterization of sunflower oils which caused only 2.9–5.8 % tocopherols decrease.