SFE of beta-Carotene in Fruits and Vegetables

Vitamin activity in foods and food products serves as an example where typical problems arise with traditional liquid solvent extraction and then where SFE has been used to address these concerns [30]. In addition to the routine assay of food products, there is a considerable amount of research being conducted on the role of carotenoids and xanthans as antioxidants in the human body. This antioxidant-role may address many health concerns such as aging and various diseases. The friendly-extracting-environment of SFE has some merit of consideration for such studies, particularly with regard to the lesser possibility of oxidation of the analytes during the sample preparation step. 

Its precursor, beta-carotene, is often the component that is added or analyzed. 

Two fundamental building-blocks of natural product chemicals are isopentyl pyrophosphate and isoprene [31, 32], Isoprene is incorporated in compounds known as isoprenoids. The function and occurrence of isoprenoids cover a very broad range in nature according to Stryer [31], -isoprenoids can bring delight by their colour as well as their fragrance. Indeed, isoprenoids can be regarded as the sensual molecules The colour of tomatoes and carrots comes from carotenoids, specifically lycopene and beta-carotene, respectively.  

Carotenoids are 40-carbon compounds made up of eight isoprene units. Carotenoids serve as light absorbing molecules in photosynthesis and also protect certain tissues from the deleterious effects of light. Beta-carotene is the precursor of vitamin A (which does not occur in plants). Beta-carotene occurs abundantly in the liver oils of fish and is extracted from that matrix commercially. Nutritionists recommend tomatoes, carrots, and green vegetables in daily quantities in order that carotenoids can be converted into vitamin A, a compound necessary for vision and other vital functions. 

Carotenes are relatively non-polar compounds which are soluble in lipophilic solvents. Most of the known natural carotenoids are oxygenated compounds, often termed xanthophylls, and may be classified as derivatives of the hydrocarbons lycopene or alpha-, or beta-carotene. Although alpha, beta, and gamma all have vitamin A activity in food products, only beta-carotene is used for calculating the vitamin A in vegetables. Carotenes are readily oxidised by light, air and many of the typical extraction solvents (or solvent impurities) including tetrahydrofuran (THF), chloroform, methylene chloride and hexane. 

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