Color lipid emulsions

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... 

Nile Blue is used as a 0.01 to 0.1 %W/V aqueous solution and is simply added to or mixed with the substrate. The active component of the dye is actually a minor contaminant of the solution, not the blue-colored material [31]. The preparations are viewed with 450-490 nm excitation (an FTTC filter set. Figure 6). Emulsion stability is sometimes an issue in the presence of the cationic blue component of Nile Blue. In this case we use Nile Red, the pure form of this colorant. Nile Red solution is made fresh from a stock solution (0.1%W/V in acetone). This stock is added dropwise to water until a moderate blue color is seen and the solution is used immediately (it deteriorates quickly). For either colorant, the active molecule is fluorescent only when it is in a suitably hydrophobic environment. This usually means neutral lipid droplets [31] but other sites (aggregates of surfactants, the center of casein micelles, cutin plates in some seeds) are possibilities. 

Steroids are lipids found in living systems that all have the ring system shown in Figure 3.8 for cholesterol. Steroids occur in bile salts, which are produced by the liver and then secreted into the intestines. Their breakdown products give feces its characteristic color. Bile salts act on fats in the intestine. They suspend very tiny fat droplets in the form of colloidal emulsions. This enables the fats to be broken down chemically and digested. 

The lipid peroxidation inhibitory activities of EOs are assessed by the P-carotene bleaching tests (Yadegarinia et al., 2006). In this method, the ability to minimize the coupled oxidation of P -carotene and linoleic acid is measured with a photospectrometer. The reaction with radicals shows a change in this orange color. The P-carotene bleaching test shows better results than the DPPH assay because it is more specialized in lipophilic compounds. The test is important in the food industry because the test medium is an emulsion, which is near to the situation in food, therefore allowable alternatives to synthetic antioxidants can be found. An only qualitative assertion uses the TLC procedure. A sample of the EOs is applied onto a TLC plate and is sprayed with P-carotene and linoleic acid. Afterwards, the plate is abandoned to the daylight for 45 min. Zones with constant yellow colors show an antioxidative activity of the component (Guerrini et al., 2006). 

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