The Influence of Traditional and Minimal Refining on the Minor Constituents of Canola Oil
The minimal refining method described in this study made it possible to neutralize crude canola oil using some weaker alkali such as Ca(OH)2, MgO and Na2siO3 as an alternative for NaOH. After citric acid degumming, more than 98% of phosphorous content was removed from crude oil. The free fatty acid content after minimal neutralization with calcium hydroxide decreased from 0.50 to 0.03%. Other quality parameters such as peroxide value, anisidine value and chlorophyll content were within commercially acceptable levels. The use of Trisyl silica and Magnesol R60 made it possible to remove the hot water washing step and to decrease the amount of remaining soap to less than 10 ppm. There was no significant change in chemical characteristics of canola oil after wet and dry bleaching. During traditional neutralization, total tocopherol loss was 19.6% while minimal refining with Ca(OH)2, MgO and Na2siO3 resulted in 7.0, 2.6 and 0.9 % reduction in total tocopherols. Traditional refining removed 23.6% of total free sterols, although after minimal refining free sterols content did not change significantly (p<0.05). Both traditional and minimal refining resulted in almost complete removal of polyphenols from canola oil. Total phytosterols and tocopherols in two cold press canola oils were 7700, 8400 mg/kg and 370, 350 mg/kg, respectively. Total phytosterols and tocopherols contents in solvent extracted canola oil were 9500, 500 mg/kg, respectively. The minimal refining method described in this study was a new practical approach to remove undesirable components from crude canola oil confirmed with commercial refining standards as well as preserving more healthy minor components.