Chlorophyll in vegetable oils

Tan, Y.A., Low, K.S., and Chong, C.L., Rapid determination of chlorophylls in vegetable oils by laser-based fluorometry, J. Sci. Food Agric., 66, 479, 1994. Bhattacharya, D. and Medlin, L., Algal phylogeny and the origin of land plants, Plant Physiol., 116, 9, 1998. 

Puspitasari-Nienaber, N.L. Ferruzzi, M.G. Schwartz, S.J. 2002. Simultaneous detection of tocopherols, carotenoids, and chlorophylls in vegetable oils by direct injection C30 RP-HPLC with coulometric electrochemical array detection. J. Am. Oil Chem. Soc. 79 633 640. 

The detection and quantification of tocopherols, carotenoids, and chlorophylls in vegetable oil were effectively used for authentication pnrposes. The presence of tocopherols, carotenoids, and chlorophylls influence the oxidative stability of vegetable oils and their potential health benefits. Puspitasari-Nienaber et demonstrated the application of a rapid and reliable analysis method of direct injection of C-30 RP-NPLC with electrochemical detection for the simultaneous analysis of the above mentioned substances. Aliquots of vegetable oils were dissolved in appropriate solvents and injected directly without saponification, thus preventing sample loss or component degradation. Thus the effective separation of tocopherols, carotenoids, and chlorophylls was achieved. 

Main components of vegetable oils, including flax oil, are triglycerols and usually contribute more than 90% of all components (Table 1). Minor components in flax oils were found to be at the similar level as in canola and soybean oils (10). The presence of chlorophyll in flax oil usually indicates immaturity of flaxseed. 

Of the substances that are present in foods, the most important photosensitisers are chlorophylls, phaeophytins, haem pigments and riboflavin. In vegetable oils, chlorophylls (and their degradation... 

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. 

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... 

The results of comparative study of sorption properties of carbomineral sorbents (initial and modified form) on the purification of technological solution are demonstrated on Fig. 1-2. It is seen that carboncontaining sorbents provide efficient purification of iquid hydrocarbons and diesel oil from toxic impurities - chlorophyll and carotene. The absence of toxic impurities in liquid carbohydrate - vegetable oil (firom rape) provides, as it was stated by us experimentally, its high heating capacity as a component of biodiesel fuel. As... 

The stability of olive oil compared with other vegetable oils is attributed to the high-to-low ratio of oleic to linoleic acid, and to the degradation of the chlorophylls to pheophytins (60). In addition, olive oil is also rich in antioxidative phenolic compounds such as hydroxytyrosol (66). 

Carotenoids and chlorophylls are the major lipochromes of vegetable oils. Cmde regular sunflower oil is not particularly rich in carotenoids (as palm oil is) or in chlorophylls (like rice bran, rapeseed, olive, and avocado oils). This gives cmde regular sunflower oil its light-amber color, turning to pale yellow upon the bleaching operation. 

Koseoglu et al. [51] examined 15 different UF membranes in the removal capacity of pigments in various vegetable oils, including soybean, canola, cotton seed oil, and peanuts. Only five membranes were resistant to hexane however, their identifications were not disclosed. Chlorophyll and p-carotene were retained by membranes, but efficiency varied between membranes and oils. In general, color readings in permeated oils were on the order of one-tenth of those obtained in crude oils. 

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]. 

Subsequent work by Zambiazi and Przybylski (1998) also showed that fatty acid composition could only explain half of the oxidative stability of vegetable oils including canola oil. The other half was attributed to the amount and composition of endogenous minor components which can shorten or extend the shelf-life of an oil. Such endogenous components were later discussed by Przybylski and Eskin (2006) and included tocopherols, mono- and diacylglycerols, free fatty acids, phospholipids, chlorophylls and derivatives, carotenoids, phytosterols, phenolic compounds and trace metals. In addition, the position that the fatty acid occupies in the triacylglyc-erol can also affect stability. For example, the location of linolenic and linoleic acids on the sn-2 position has been reported to cause faster oxidation and lower stability compared to the same fatty adds on ml- and sn-3 positions. In contrast oleic acid at the sn-2 position proved stabler compared to its location on sn-1 and sn-3 positions (Neffetal., 1994,1997). 

Minor components of canola oil include tocopherols (700-1200 ppm of mainly a and Y tocopherols) and chlorophylls (5-35 ppm). The a-tocopherol (vitamin E) content of canola oil is 2.44 mg/tablespoon (USDA, 2010). This is higher than most vegetable oils except snnflower and safflower oils (USDA, 2010). The y-tocopherol content is not readily reported, but in canola oil is typically abont 1.5 times that of the a-tocopherol content (Przybylski, 2010). The RDA for Vitamin E for adults is 15 mg/day. Most of the trace elements found in the canola plant such as phosphorus, iron, calcinm, snlphnr, zinc and lead are removed or minimzed during processing (Przybylski, 2010). 

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. 

---