Chlorophyll removal

D. D. Brooks and co-workers, "The Synergistic Effect of Neutral Bleaching Clay and Citric Acid Chlorophyll Removal," paper presented at the... 

S. K. Brophy and co-workers, "Chlorophyll Removal from Canola Oil A New Concept," paper presented at the 80th AnnualAOCS Meeting, Cincinnati, Ohio, 1989. 

How is the magnesium in chlorophylls removed and how are vanadium and nickel introduced ... 

Pritchett, W.C. Taylor, W.G. Carroll, D.M. Chlorophyll removal during earth bleaching of soybean oil. J. Am. Oil... 

Diosady L.L. Chlorophyll removal from edible oils. International Journal of Applied Science and Engineering, 3 81-88 (2005). 

Baroi, C., Dalai, A.K., 2013. Simultaneous esterification, transesteriflcation and chlorophyll removal from green seed canola oil using sohd acid catalysts. Catalysis Today 207,74—85. 

Green coloration, present in many vegetable oils, poses a particular problem in oil extracted from immature or damaged soybeans. Chlorophyll is the compound responsible for this defect. StmcturaHy, chlorophyll is composed of a porphyrin ring system, in which magnesium is the central metal atom, and a phytol side chain which imparts a hydrophobic character to the stmcture. Conventional bleaching clays are not as effective for removal of chlorophylls as for red pigments, and specialized acid-activated adsorbents or carbon are required. 

Solvent extraction removes chlorophyll and other pigments to give a light-colored product but increases processing costs. Furthermore, solvent extraction removes p-carotene and reduces vitamin A activity (89) (see Terpenoids Vitamins). Supercritical CO2 extraction at 30 and 70 MPa (4,350 and 10,150 psi) and 40°C removed 90 and 70% carotene and lutein, respectively, from alfalfa LPC (96). This process avoids organic solvent residues and recovers valuable by-products. 

Fats and Oils. The oxidation of fats and oils in food products can be prevented by the addition of citric acid to chelate the trace metals that catalyze the oxidation. Citric acid is also used in the bleaching clays and the degumming process during oil refining to remove chlorophyll and phosphohpids (59—63). 

Several chemical transformations in the chlorin series were discovered during the course of Woodward s total synthesis of chlorophyll a.3a d An important reaction in the final steps of this total synthesis is the removal of an a-oxo acid ester residue from the 17-position of the chlorin 22, which proceeds very smoothly in the presence of base by a retro-aidol-type fragmentation to yield the chlorin isopurpurin methyl ester (23) which is also available by degradation of chlorophyll a, so that at this point of the synthesis synthetically derived material could be compared with an authentic sample prepared from natural chlorophyll a. 

These extensive alterations in cell structure and the biochemical machinery are indicative of entry into an ametabolic condition. In this condition damage from free radicals is potentially decreased, certainly the loss of chlorophyll and chloroplast structure removes a major source of free radical generation. About 50% of the extremely desiccation tolerant monocots exhibit extensive loss of chlorophyll and ultrastructural organisation when desiccated. Dicots, ferns and bryophytes retain most of their chlorophyll and exhibit small changes in structure when dry (see Gaff,... 

Esterification increases the lipophilic character of the pigments that has been recogiuzed as an important factor for interactions with the peptide chains of proteins. The hydrolysis of this side chain results in chlorophyllides and the concomitant removal of the Mg + ion in pheophorbides. Only a Umited number of natural chlorophylls in plants and photosynthetic organisms has been described and is well... 

Because of the role these algae play in the oceans biological productivity and their impacts on climate due to the removal of carbon dioxide, satellite sensors have been employed to measure the chlorophyll a contents in oceans, lakes, and seas to indicate the distribution and abundance of biomass production in these water bodies. Detection is set at the specific reflectance and absorption wavelengths of the light from the upper layer of the ocean where photosynthesis occurs. 

Traditionally, dried or powdered plant material is used and extracts can be obtained by mixing the material with food-grade solvents like dichloromethane or acetone followed by washing, concentration, and solvent removal. The result is an oily product that may contain variable amounts of pheophytins and other chlorophyll degradation compounds usually accompanied by lipid-soluble substances like carotenoids (mainly lutein), carotenes, fats, waxes, and phospholipids, depending on the raw material and extraction techniques employed. This product is usually marketed as pheophytin after standardization with vegetable oils. 

Lipid-soluble food grade copper chlorophyll is manufactured similarly by extraction of adequate plant material, followed by replacement of magnesium by copper, and purihcation steps to remove carotenoids, waxes, sterols, oils, and other minor components that are co-extracted. Commercial copper chlorophylls may vary physically, ranging from viscous resins to fluid dilutions in edible oils as well as granulated forms and emulsions standardized with edible vegetable oil. Colors may vary... 

Alkaline hydrolysis (saponification) has been used to remove contaminating lipids from fat-rich samples (e.g., pahn oil) and hydrolyze chlorophyll (e.g., green vegetables) and carotenoid esters (e.g., fruits). Xanthophylls, both free and with different degrees of esterification with a mixture of different fatty acids, are typically found in fruits, and saponification allows easier chromatographic separation, identification, and quantification. For this reason, most methods for quantitative carotenoid analysis include a saponification step. 

Typically lipids, chlorophyll, and phenolic acids can be separated by liquid-liquid partition. Lipids and chlorophyll can be removed from acetone-water extracts by chloroform while phenolic acids have higher affinities for ethyl acetate at a pH close to nentral and water. °°... 

Chlorophylls a and b and, in smaller amounts, chlorophylls a and b can be found in any photosynthetic tissue obtained from land plants. They may thus be extracted from an almost infinite number of sources [23], although it is easier to work with material containing relatively litde water as this has to be removed at later stages of the workup. Thus, woodier tissues are to be preferred as sources as compared to those containing large volumes of water, e.g., parsley rather than cucumber. 

Isolation of Sesquiterpene Lactones. The ether extract was evaporated and dissolved in 952 ethanol. Then an equal volume of 42 aqueous lead acetate was added. After 1 hour the mixture was filtered to remove precipitated chlorophyll and phenolic products and the ethanol removed under vacuum. The aqueous layer was extracted with chloroform giving a dark colored oil from which the sesquiterpenes were isolated by a combination of chromatographic procedures, i.e., LH-20 gel permeation, silica gel using both packed columns and thin layer plates. A variety of solvents were also used to purify the individual sesquiterpene lactones, e.g., benzene-acetone (1 1), ethyl acetate, chloroform-methanol (9 1). On thin layer chromatographic plates, spots were visualized by spraying with 22 aqueous KMn04 solution. 

Chlorophyll and some red constituents should be removed prior to color development. 

---