Rice bran phytosterols

Phytosterols have been demonstrated as being anti-cancer components in the diet (Awad and Fink 2000). Scientific studies indicate that phytosterols may offer profection against colon, breast and prostate cancers (Vanderhaeghe and Bouic, 2000). The possible mechanisms, as reported by these authors, include the effect of phytosterols on membrane structure and function and on the signal transduction pathways that regulate tumor growth and apoptosis. The rice bran derived phytosterol-cycloartenol-ferulic acid ester on the central nervous system has been studied by Hiraga et al. (1993). 

Natural products have been noted for their potential health benefits from time immemorial and are the basis of Ayurveda, an ancient Indian medical practice (Bushkin and Bushkin, 2002). However, the potential benefits of several natural products reside in one or two active ingredients. For example green tea stands for polyphenols, soy for soy estrogens, broccoli for isothiocyanates and grape seed for polyphenols. The beauty of rice bran is that there are more than 100 antioxidants, several categories of bioactive phytonutrients, such as IP6, polyphenols, phytosterols, tocotrienols, y-oryzanol, B vitamins, minerals and trace minerals in addition to fat, protein, fiber, polysaccharides and other nutrients. These phytonutrients and antioxidants of rice bran are believed to act at the cellular level, and their synergestic function is responsible for the positive health benefits. 

Hiraga, Y., N. Nakata, H. J in, et al. Effect of the rice bran-derived phytosterol cycloartenol ferulic acid ester on the central nervous system. Arz-neim-Forsch 1993 43(7) 715-721. Mao, X. H., R. P. Xu, S. G. Wang, et al. Simultaneous extraction of oryzanol and yazhouning from crude rice bran oil. Patent-Faming Zhuanli Shenqing Gongkai Shuomingshu—1,067,448 1992 14 pp. 

Dunford, N. T., and King, J. W. 2000. Phytosterol enrichment of rice bran oil by super critical carbondioxide technique. I. Food Sci., 65,1395-1399. 

The majority of the crude oils contain 1000-5000 ppm sterols. Exceptions are com and rice bran oil that may contain up to 1-2% of phytosterols (Table 9). 

Supercritical CO2 column fractionation of soybean (57, 86, 88, 89) and rice bran oil (57) deodorizer distillates has been investigated to enrich their sterol and tocopherol contents. Brunner et al. (89) reported that the FFA were enriched in the top (in the extract), whereas the monoacylglycerols, tocopherols, and diacylglycerols were enriched in the bottom (in the raffinate) fraction during the fractionation of soybean oil deodorizer distillate. Saure and Brunner (88) achieved a tocopherol concentration of more than 70% (w/w) using continuous column fractionation of soybean deodorizer distillate where squalene was almost completely found in the top product, whereas sterols and tocopherols were enriched in the bottom product. King and Dunford (57) developed a two-step column fractionation scheme (13.6 MPa and 27.2 MPa at 313 K) for the enrichment of phytosterols from soybean and rice bran oil deodorizer distillates such that the FFA were removed in the first step and sterols were enriched in the oil fraction in the second step. 

One approach to increase the plQlosterol ester content of vegetable oils is via refining rather than isolating em from the by-products and then adding them back to the oil (26). Such a processing scheme simplifies the eruichment process and improves the economic feasibility of the production. Dunford and fCing (27) were able to increase the total phytosterol ester content of rice bran... 

Three distinct processes were experimentally studied a coupled process for deacidi%ing and enriching the plqrtosterol content of rice bran oil (RBO) by continuous countercurrent colnitmar fiactionation, a scale up of a coupled supercritical fluid extraction (SFE)/ supercritical fluid chromatogr hy (SFC) process for the enrichment of phytosterol in com bran oil, and a unit process involving the snbcritical water extraction of berry substrates. The e q)erimental aspects of the first two processes are described in the literature (36, 37), and will not be repeated here. Research is currently underw to couple the described process below with other unit processes involving both subcritical water and siq)ercritical carbon dioxide. 

The aleurone layers of com, wheat, rye, and triticale have a high percentage of samrated phytosterols (i.e., sitostanol and campestanol), which are esterified to ferulic acid (Figure 6.3), and to p-coumaric acid to a much lesser extent in com. Rice bran differs from most other cereals in having mostly 30- and 31-carbon sterols (triterpenoids) esterified to femlic acid and small amounts of typical sterols (Moreau et al., 1996). 

Lipids are essential components in the diet and nutritionists should be more active in arguing the positive aspects of these molecules. They are required in their own right and also for the important minor components such as carotenoids, tocols, and sterols which accompany the oils and fats. The first chapter in the book is an overview of the development of functional foods and this is followed by chapters devoted to materials which are either lipids or are compounds that are fat-soluble and co-occur with oils and fats. These include carotenoids, tocopherols, phytosterols, omega-3 (n-3) oils, diacylglycerols, structured lipids, sesame oil, rice bran oil, and oils or preparations containing palmitoleic acid, y-linolenic acid, stearidonic acid, or conjugated linoleic acid. These topics will be of interest to those who produce lipids and those who seek to incorporate them into appropriate foods, and this book is directed primarily to these two groups. 

Dunford, N.T., Teel, J.A. and King, J.W. 2003. A continuous countercurrent supercritical fluid deacidiflcation process for phytosterol ester fortification in rice bran oil. Food Res. Int. 36 175-181. 

Dunford NT, King JW. 2000. Phytosterol Enrichment of Rice Bran Oil by a Supercritical Carbon Dioxide Fractionation Technique. J. Food Sd. 65 1395-1399. 

Dunford NT, Teel JA, King JW. 2002. A Continuous Countercurrent Supercritical Huid Deacidification Process for Phytosterol Ester Fortification in Rice Bran Oil. Food Research Intenational 36(2) 175-181. 

Stabilized whole rice bran is rich in protein, lipids, dietary fiber, vitamins, essential minerals, and important nutraceuticals such as phospholipids, choline, inositol, phytosterols, tocols, and tocotrienols. Tocols and tocotrienols are potent antioxidants that reduce the risk of cancers and CVD. The whole rice bran is stabUized in order to denature lipases that cause oxidative rancidity and to protect the intrinsic nutraceutical compounds. The stabilization of the rice bran is usually done by applying heat in an extrnder. The preservation of the oryzanol is of utmost importance because this compound is very effective in promoting cardiovascular health (Hoffpauer 2005). 

More than two decades ago I began my search for ways to lower my own cholesterol levels and prevent an early death from heart disease. Certainly, the essential foundation of sueh a program had to include increased physical activity and a heart-healthy diet. But knowing that other factors entered into the cholesterol picture—notably, that the body makes 80 percent of all the cholesterol in the bloodstream—I realized that I needed something more than diet and exercise. My search led me to the soluble fibers in oat bran and other foods that actually flush out cholesterol and the vitamin niacin to stop the body s excessive production of it. Since that time, I ve found additional natural approaches to lowering cholesterol, including the plant sterols known as phytosterols, red yeast rice, and pantethine. 

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