Sterol -- One kind of Steroid, the basic structure is cholestane, 3 β-hydroxide cholestanes, is one kind of saturated sec-alcohol or unsaturated sec-alcohol. When abstract the fat from the tissue of animals or plants by fat-solvent, there are normally some contents that can not be saponified by alkali. These contents are always with basic structure of perhydrocyclopentanophenanthrene, and so called sterol compounds. It is existed inside animal body as ester, and inside plant as glycoside.

I. Cholesterol (or Cholesterin) exists inside the nerve tissues of animal’s blood, fat and brains, and many inside the vitellus of eggs, is colorless or slightly yellow crystalline. The melt point is 148.5?C, slightly dissolve in water, easily dissolve in the chloroform of hot ethanol and aether. Cholesterin has character of aliphatic sec-alcohol and azole, and can appear color combined with some compounds, and also can make qualitative experiment as steroid compounds. If there are more Cholesterol in body, it can cause gall-stone and atherosclerosis. Cholesterol is used as raw material for composition of Vitamin D3.
II. Vitamin D, always exists with Vitamin A inside cod liver oil, vitellus, cream and etc. Vitamin D has two kinds Vitamin D2 (calciferol or calcidol ) and Vitamin D3 (cholecalciferol). There are many dehydrocholesterol –the precursor of Vitamin D3 inside the animal tissue or human being skin; and there are many ergosterol – the precursor of Vitamin D2 inside yeast. When these two substances are irradiated by ultraviolet radiation, they can be transferred to Vitamin D3 and D2. The function of Vitamin D2 and D3 are very similar, they are good Vitamins to antirickets.

Corn bran is the main by-product when producing maize starch. We have a national annual corn bran quantity about 1million to 1.5 million, and most of them are not efficiently used. In these corn bran, there are many fibrin, hemicellulose, pectin, protein, Vitamin, Sterol, mineral and etc. Plant Sterol has functions of diminishing inflammation, lowering blood lipid, anti-knub, anti-abscess and etc., and is well concerned by many scientific researches. If successfully use supercritical carbon dioxide fluid and short path molecular distillation technology to abstract out the corn Sterol agent from the Sterol compounds inside corn bran, this research can promote the utilization of the corn bran and realize the recycle economy and further process of resources.