Colorants applications

Methods are described for determining the extent to which original natural color is preserved in processing and subsequent storage of foods. Color differences may be evaluated indirectly in terms of some physical characteristic of the sample or extracted fraction thereof that is largely responsible for the color characteristics. For evaluation more directly in terms of what the observer actually sees, color differences are measured by reflectance spectrophotometry and photoelectric colorimetry and expressed as differences in psychophysical indexes such as luminous reflectance and chromaticity. The reflectance spectro-photometric method provides time-constant records in research investigation on foods, while photoelectric colorimeters and reflectometers may prove useful in industrial color applications. Psychophysical notation may be converted by standard methods to the colorimetrically more descriptive terms of Munsell hue, value, and chroma. Here color charts are useful for a direct evaluation of results. 

Besides their interesting color application values, betalainic plants are also worthwhile from a nutritional standpoint. Research on this topic has recently been resumed with great scientific vigor in both in vitro and in vivo studies on red beets, amaranth, red-colored Swiss chard, red-violet pitahayas, and especially cactus pears. ° In the future, betalainic color crops will be benchmarked because of their pigment structure and quantity and also because of the individual and synergistic activities of their components such as colorless phenolics, amino compounds, peptides, proteins, and hydrocolloids. 

Charge carriers, in silicon-based semiconductors, 22 237-239 Charge control additives, in paper manufacture, 13 116-117 Charge-coupled devices (CCDs), 19 132, 142-143 23 143, 144 26 421 arrays of, 22 267 in chemical analysis, 19 150 color applications of, 19 147 consumer applications of, 19 148 design type and application for,... 

An overview of the effect of crystal structure on color application properties of organic pigments was published [7]. 

This section will discuss some important concepts from coloristic practice and the optical properties of pigmented systems. Space considerations permit a treatment of only the most vital concepts. The reader must consult the literature for further details and accounts of special problems [1], A review on the effect of crystal structure on color application properties was published [2],... 

The yellow crocins from gardenia have received some success for the same colorant applications as saffron,37 but the iridoid derivatives have not received the same promotion. The range of colorants available from the same source would seem to make them attractive possibilities. 

Many industrial color applications work with a color spectrophotometer to measure CIELAB color differences. CIELAB works well in specifying the color of an object, but color differences calculated with the formula have limited value for pass/fail decisions. These component color differences (dL, da, db ) are calculated by simply subtracting the L a b values for the standard from the L a b values for the trial. The dL, da, db values should indicate the direction of color difference from the standard (e.g., lighter or darker). They are commonly used to establish the allowable color limits from a standard. However, in applying these delta differences as limits for color acceptability, they should be adjusted for different colors. CIELAB, like Hunter L,a,b, is not a visually uniform color space. The limitations of CIELAB are not well understood throughout industry and the numbers continue to be applied without being adjusted for different colors and products. 

The emphasis on control in certain color applications has resulted in tighter color tolerances. Color tolerances need to be realistic so they are achievable when considering the variables introduced by people, products, and instruments. The acceptable limits should not be set at the minimum limit of what a human observer can perceive. Added to this is the visual nonuniformity that exists for both perceptible and acceptable limits. Human observers do not respond equally to all colors. Hopefully, a uniform color difference equation could be available that adjusts the perceptibility and acceptability limits for individual colors. 

Triarylmethane dyes are derivatives of triphenylmethane and diphenylnaphthylmethane. The presence of one or more primary, secondary, or tertiary amino or -OH groups in the para position to the methane carbon determines the dye color. Halogen, carboxyl, or sulfonic acid substituents also may be present on the aromatic rings. Triarylmethane colorant applications include basic, acid, solvent, and mordant dyes. Major uses are in printing inks. 

In practice, there are many sources of error apart from the inaccuracies of theory. In addition, there is human error, measurement error, batch variation of the colorants, and the nonreproducibility of the coloration process itself [2], Once a process is under control, the next step is to apply color formulation software. It has been shown that many of the past methods have not proven to be completely viable for the variety of color applications encountered today. 

A more fundamental limitation of the chalcogenide glasses is that they cannot be prepared in a flexible configuration. This poses certain process limitations for high-volume and color applications. In the case where the... 

Hunger, K. (1999). The effect of crystal structure on color application properties of organic pigments. Rev. Prog. Coloration and Related Topics, 29,11-84. [258,259, 268]... 

Kodak Ltd. Emulsions photographiques et colorants applicables en particu-... 

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