Ethanol carotenoid extraction

The carotenoid extract obtained by extraction of fresh food with a water-soluble solvent contains large amounts of water from the sample. In order to remove the water and solvent, in the case of acetone, carotenoids are transferred to petroleum ether, diethyl ether, or a mixture by adding small portions of the solvent extract and a large amount of water in a separatory funnel. The remaining traces of water can be removed either by addition of anhydrous Na2S04 or ethanol to form the azeotropic mixture. 

An open column packed with neutral aluminium oxide (grade III) slurry is generally used for semi-preparative separation of large amounts of carotenoid extract, revealing three broad bands (1) carotenes and epoxy-carotenes constitute the first fraction to elute with petroleum ether, (2) monohydroxy and keto-carotenoids with 50 to 80% diethyl ether in petroleum ether are next, and (3) finally, the polyhydroxy carotenoids elute with 2 to 5% diethyl ether in ethanol or... 

The solvent used for extraction must be chosen according to the polarity of the pigments presumably present. If this characteristic is unknown, an acetone/hexane (1 1, v/v) mixture is suitable. When it is known that the carotenoids in the sample are nonpolar or are in the ester form, hexane is a good choice for extraction. Ethanol will extract polar carotenoids, and a nonpolar solvent like hexane will promote crystallization. 

In a previous work, we studied the possibility of extracting antioxidants from microalgae Spirulina platensis using ASE with different solvents (33-34). Likewise, other authors have studied the carotenoids extraction from microalgae Haematococcus pluvialis and Dunaliella salina using ethanol as solvent and ASE (35). 

The membrane separation process was initially conducted in degumming vegetable oil and then was adapted for the recovery of carotenoids. Dense polymeric membranes are employed in this system and are very effective in the separatirm of xanthophylls, phospholipids, and chlorophyll, with retention of 80-100 %, producing an oil rich in carotenes [72,73]. This process, however, requires an additional step of hydrolysis or transesterification. Chiu, Coutinho, and Gruigalves examined the membrane technology as an alternative to concentrate carotenoids from crude palm oil in detriment of ethyl esters. A flat sheet polymeric membrane constituted by polyethersulfone was used and obtained a retention rate of 78.5 % [74]. Damoko and Cheryan obtained similar results using nanofiltration with 2.76 MPa and 40 °C in red palm methyl esters [75]. Whereas Tsui and Cheryan combined ultraiiltration with nanofiltration to separate zein and xanthophylls from ethanolic com extract [76]. 

The shape of the absorption spectrum of the carotenoid, and the positions of the absorption maxima, can vary depending on the interactions of the molecule with the solvent or lipid environment in which it is dissolved. In general, solvents with low polarity have little effect on the position of the absorption maxima, so that for a given carotenoid, the values of Aniax are almost identical in hexane, light petroleum, diethyl ether, methanol, and ethanol. Acetone, commonly used in carotenoid extraction, causes a bathochromic displacement of around 2-6 nm in the maxima compared with the aforementioned. In contrast, very polar solvents such as chloroform, benzene, and pyridine cause very significant bathochromic displacements (10-25 nm), which are extreme in the case of carbon disulfide (30-40 nm). 

Plant carotenoids are still extracted at laboratory and industrial scales with solvent mixtnres of ethanol and ethyl acetate, bnt solvent extraction always bears the risk of toxic residnes in the extracts and this limits their use in large production applications in the food and pharmaceutical industries. 

Enzyme-mediated extractions — Selective enzyme-mediated extraction of cap-sacinoids and carotenoids from Chili Guajillo Puja using ethanol as a solvent was... 

In another study of carotenoid accumulation, cultured ARPE-19 cells were treated with a lipophilic extract from tomatoes solubilized in ethanol and injected into the culture medium for 24 h. The extract, containing 3-carotene, lycopene, and lutein at relative ratios of 23, 13, and 1, respectively, led to internalization of carotenoids at ratios of 9, 1.3, and 1, respectively (Chichili et al., 2006). These results indicate preferential accumulation of (3-carotene and lutein over lycopene in ARPE-19 cells. 

The foliage of the food plants was ground and the pigments were extracted into warm methanol and saponified in 4% sodium hydroxide. The carotenoids were extracted into dichloromethane, dried, and redissolved in ethanol prior to an analysis by HPLC. 

Use of cosolvent. Various cosolvents, such as acetone, ethanol, methanol, hexane, dichloromethane, and water, have been used for the removal of carotenoids using SC-CO2 extraction (Ollanketo and others 2001). All these cosolvents except water (only 2% of recovery) increased the carotenoid recovery. The use of vegetable oils such as hazelnut and canola oil as a cosolvent for the recovery of carotenoids from carrots and tomatoes have been reported (Sun and Temelli, 2006 Shi, 2001 Vasapollo and others 2004). For the extraction without cosolvent addition, the lycopene yield was below 10% for 2- to 5-hr extraction time, whereas in the presence of hazelnut oil, the lycopene yield increased to about 20% and 30% in 5 and 8 hr, respectively. The advantages of using vegetable oils as cosolvents are the higher extraction yield the elimination of organic solvent addition, which needs to be removed later and the enrichment of the oil with carotenoids that can be potentially used in a variety of product applications. 

Carotenoids A large number of solvents have been used for extraction of carotenoids from vegetables matrices, such as acetone, tetrahydrofuran, n-hexane, pentane, ethanol, methanol, chloroform [427-431], or solvent mixtures such as dichloromethane/methanol, tetrahydrofuran/methanol, -hexane/acetone, or toluene or ethyl acetate [424,432-435], SPE has been used as an additional purification step by some authors [422,426], Supercritical fluid extraction (SEE) has been widely used, as an alternative method, also adding CO2 modifiers (such as methanol, ethanol, -hexane, water, methylene chloride) to increase extraction efficiency [436-438], In addition, saponification can be carried out, but a loss of the total carotenoid content has been observed and, furthermore, direct solvent extraction has been proved to be a valid alternative [439],... 

The extraction of chlorophylls and carotenoids from water-containing plant materials requires polar solvents, such as acetone, methanol, or ethanol, that can take up water. These extracts must then be transferred to a solvent such as diethyl ether in order to be stored stably. Samples with very high water content, such as juices and macerated plant material, are usually freeze-dried first, and can then be extracted directly with diethyl ether. After extraction, solutions are clarified and diluted to an appropriate volume to measure chlorophyll content by UV-VIS spectrophotometry. Absorption coefficients and equations needed for quantitative determination are given in unitf4.3. 

Water-containing plant materials need to be extracted with polar solvents such as acetone, methanol, or ethanol that can take up water. Freeze-dried plant tissues and freeze-dried juices can be directly extracted with diethyl ether, which contains traces of water and is more polar than light petrol or hexane. Pure light petrol or hexane are less suitable, because more polar pigments, such as Chi b or xantho-phylls, are only partially extracted from freeze-dried plant samples. A few drops of acetone or ethanol added to light petrol or hexane will, however, guarantee a complete extraction. This mixture will extract Chi a, Chi b, and all carotenoids—including xanthophyll esters and secondary carotenoids that are present in many fruits and juices—from the freeze-dried plant material. 

Carotenoids should be extracted from tissues as rapidly as possible. If an immediate extraction is not possible, samples should be stored below — 18°C until required. For the extraction the exactly weighed sample and the solvent are transferred into a blender, where the sample is simultaneously grinded and extracted. Since fresh tissues contain a high percentage of water, and carotenoids are lipo-soluble, the first organic solvent must be miscible with water (e.g., acetone, ethanol, methanol). After one or two extraction steps, water-immiscible solvents (e.g., diethyl ether, benzene) can be applied. Dried materials may be also extracted with water-immiscible solvents, but carotenoid recovery is usually better if the tissue is first treated with a little water and then extracted with water-miscible solvents. Prior to the extraction of fruits the addition of antioxidants [e.g.,... 

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