Effect of refining of crude rice bran oil on the retention of oryzanol in the refined oil

Abstract

The effect of different processing steps of refining on retention or the availability of oryzanol in refined oil and the oryzanol composition of Indian paddy cultivars and commercial products of the rice bran oil (RBO) industry were investigated. Degumming and dewaxing of crude RBO removed only 1.1 and 5.9% of oryzanol while the alkali treatment removed 93.0 to 94.6% of oryzanol from the original crude oil. Irrespective of the strength of alkali (12 to 20° Be studied), retention of oryzanol in the refined RBO was only 5.4-17.2% for crude oil, 5.9-15.0% for degummed oil, and 7.0 to 9.7% for degummed and dewaxed oil. The oryzanol content of oil extracted from the bran of 18 Indian paddy cultivars ranged from 1.63 to 2.72%, which is the first report of its kind in the literature on oryzanol content. The oryzanol content ranged from 1.1 to 1.74% for physically refined RBO while for alkali-refined oil it was 0.19-0.20%. The oil subjected to physical refining (commercial sample) retained the original amount of oryzanol after refining (1.60 and 1.74%), whereas the chemically refined oil showed a considerably lower amount (0.19%). Thus, the oryzanol, which is lost during the chemical refining process, has been carried into the soapstock. The content of oryzanol of the commercial RBO, soapstock, acid oil, and deodorizer distillate were in the range: 1.7-2.1, 6.3-6.9, 3.3-7.4, and 0.79%, respectively. These results showed that the processing steps-viz., degumming (1.1%), dewaxing (5.9%), physical refining (0%), bleaching and deodorization of the oil-did not affect the content of oryzanol appreciably, while 83-95% of it was lost during alkali refining. The oryzanol composition of crude oil and soapstock as determined by high-performance liquid chromatography indicated 24-methylene cycloartanyl ferulate (30-38%) and campesteryl ferulate (24.4-26.9%) as the major ferulates. The results presented here are probably the first systematic report on oryzanol availability in differently processed RBO, soapstocks, acid oils, and for oils of Indian paddy cultivars.

Natural antioxidants of the Jaffna variety of <i>Moringa Oleifera</i> seed oil of Indian origin as compared to other vegetable oils

“…The oryzanol content in extracted crude rice bran oil was determined using the spectrophotometric method (Gopala Krishna et al, 2001) by dissolving of 290 nm and emission wavelength of 330 nm were maintained for the fluorescence detection of all the peaks. Standard α, γ and δ-tocopherols were used as external and internal standards for the identification and quantitation of tocopherols in the samples by comparing the peak retention times and peak areas of the standard compounds with those of the samples.…”

“…The total carotenoid contents of the oils were found to be in the range of 5.5-497.8 ppm in the order of decreasing prevalence of CPO > RBO > SESO > NSO > MSO > CNO with CPO containing the highest and CNO the lowest amount of carotenoids while MSO had 16.9 ppm of carotenids (Table 1). Apart from tocopherols, sterols, phenolics and carotenoids, RBO and SESO also contained oryzanol (19000 ppm) and lignans (10200 ppm) respectively, both of which have strong antioxidant and bioactive functions (Gopala Krishna et al, 2001;Namiki, 2007). The presence of natural antioxidants plays a vital role in free radical inhibition.…”

Shelf-life study of Indian traditional food based nutraceutical (oryzanol) enriched instant mixes Bhath-OZ and Upma-OZ

“…Determination of oryzanol and tocopherols content Oryzanol content of the products were determined as per published procedure on the extracted fat (Gopala Krishna et al 2001). A known amount of fat (10 mg) was accurately weighed and dissolved in hexane and made upto a known volume and the optical density at 314 nm in a 1-cm cell was measured in a UV-visible double beam recording spectrophotometer (model-UV-1601 Shimadzu Corporation, Kyoto, Japan) followed by calculation using specific extinction coefficient of 358.9 (Gopala Krishna et al 2001) and expressed as mg% of oryzanol based on the product.…”

“…A known amount of fat (10 mg) was accurately weighed and dissolved in hexane and made upto a known volume and the optical density at 314 nm in a 1-cm cell was measured in a UV-visible double beam recording spectrophotometer (model-UV-1601 Shimadzu Corporation, Kyoto, Japan) followed by calculation using specific extinction coefficient of 358.9 (Gopala Krishna et al 2001) and expressed as mg% of oryzanol based on the product. The extracted fat from products was estimated for their tocopherols content after saponification of the fat.…”

Stability of oryzanol fortified biscuits on storage

“…The crude rice bran oil contains 1.5-2.9 % oryzanol and is lost into soap stock during chemical refining of rice bran oil (Gopala Krishna et al 2001). Thus this valuable nutraceutical is not available for use.…”