Rapeseed bleaching

Refined and bleached rapeseed oil were obtained from Onbio Co. Ltd. (Pucheon-Si, Korea). Table 1 presents the fatty acid composition and characteristics of rapeseed oil. Reference standards of FAMES such as palmitic, stearic, linolenic, linoleic, and oleic methyl ester of >99% purity were purchased from Sigma (St. Louis, MO). Methanol and catalysts such as KOH, NaOH, and sodium methoxide were analytical-grade chemicals. 

Ferrari et al (1996) claimed that deodorization caused significantly more steradiene formation than the other processes, including bleaching during the refining of corn, soyabean and rapeseed oils, but most other studies have shown that bleaching is the step at which most of the steradienes are formed. 

Carotenoids and chlorophylls are the major lipochromes of vegetable oils. Cmde regular sunflower oil is not particularly rich in carotenoids (as palm oil is) or in chlorophylls (like rice bran, rapeseed, olive, and avocado oils). This gives cmde regular sunflower oil its light-amber color, turning to pale yellow upon the bleaching operation. 

The process developed by Gupta (19-22) processed crude oils with a combination of UF membrane separation and silica gel column percolation. The soybean and rapeseed-hexane miscellas were passed through various UF membranes. The solvent was removed from the permeate, and the degummed oil was then treated with bleaching clay, silica, and/or acid and finally was steam deodorized to produce refined, bleached, and deodorized oil. The color readings of the oils obtained... 

The relative composition of different vitamers remained constant during refining of soybean oil (Jung et al., 1989) and rapeseed oil (Schone et al., 1998), but in one study, a-tocopherol was selectively adsorbed on the bleaching clay (Prior et al., 1991). 

Most of the rapeseed oil is said to be utilized at the commune level mainly in the crude oil form. Some of the rapeseed oil is refined (i.e., degummed, alkali refined, bleached, and deodorized) but little is hydrogenated for production of butter substitutes (Boulter, 1980). 

At the Division of Applied Biology of the National Research Council in Ottawa, Dr. N. H. Grace, Dr. H. J. Lips, and Dr. A. Zuckerman were investigating the edible uses of rapeseed oil. They concluded that with careful refining, bleaching, hydrogenating, and deodorizing, rapeseed oil could be substituted for soybean oil in edible products without loss in quality. However, edible oil processors remained reluctant to use the oil. They felt that flavor stability was inferior to other oils available to them and because there was no firm market, seed production and oil supplies were erratic. 

Another landmark in the development and marketing of rapeseed oil was the setting of standards for the oil in 1965 under the auspices of the Edible Oils Institute. Samples of the oil from the four Western Crushers were examined in six refiner s laboratories. Specifications for free fatty acids, moisture and impurities, flash point, refined bleached color, green color in crude oil, refining loss and phosphatide content were approved and published by the Canadian Government Specifications Board. These standards have been revised periodically, the latest being in 1976. 

Modification of the Distribution of Sulfur Compounds in a Rapeseed Oil Neutralized and Bleached, Compared to the Untreated Oil, or to the Oil with Prior Deodorization ... 

Canula (rapeseed) oils c. H Colour pigment formation during bleaching and deodorization... 

Chem. Desctip. Rapeseed oil, low emcic acid, refined, bleached, deodorized CAS 120962-03-0 EINECS/ELINCS 232-299-0... 

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