Pigment content

Grayness of a fabric swatch is not directly proportional to its content of black pigment (or artificial sod). A basic formula relating reflectance to the pigment content or concentration can be appHed to the evaluation of detergency test swatches (51,99—101). In simple form, an adaptation of the Kubelka-Munk equation, it states that the quantity (1 — i ) /2R (where R is the fraction of light reflected from the sample) is a linear function of the sod content of the sample. 

Most pigments can be used in any type of binder therefore, paints cannot be identified by pigment type alone. For example, micaceous iron oxide pigment is traditionally in an oil-based binder but is being increasingly used in epoxies, etc. In the paint coating film, the pigment content may vary from 15 to 60 per cent. In the special case of zinc rich primers, it is over 90 per cent. 

Putties are heavy-bodied pastes of high pigment content that are applied by knife for rough filling of deep indentations, more especially in rough castings. 

Undercoats are invariably of high pigment content and low gloss. Their function is to provide a foundation that is uniform in both colour and texture for the finishing coats, thereby enhancing the final appearance of the completed system. On occasions, it is possible to achieve the same result by substituting an additional coat of finish for the undercoat, and this may improve the durability of the system. 

In another experiment, seawater was pumped from a sea-ice hole, incubated for 24 and 48 hours, and analyzed for pigment content. 

WETZEL c M and RODERMEL s R (1998) Regulation of phytoene desaturase expression is independent of leaf pigment content in Arabidopsis thaliana , Plant Mol Biol, 37, 1045-53. 

The overall anthocyanin analysis is generally conducted using the Giusti and Wrolstad method based on the differences in absorbance of anthocyanins at pH 1 and pH 4.5. Then the pigment content is determined using the coefficient of molar extinction of the predominant anthocyanin. It should be noted that this technique only allows dosing of anthocyanins with a color difference between the two pH values (due to transition to the flavylium cation form). A more global analysis of total anthocyanin content may be conducted by direct spectrophotometry of the... 

Nilsson, T., The pigment content in beetroot with regard to cultivar, growth, development and growing conditions, Swed. J. Agric. Res., 3, 187, 1973. 

The fortunate constellation of scientists at Wisconsin facilitated further achievements toward increasing pigment content in red beets. In a recurrent selection program, betalain contents of red beet crops were enhanced by 200%. This example should encourage both food scientists and plant breeders to join forces and invest in the improvement of promising color crops. 

Association of pigment accumulation with DNA features can inform systematics and applied breeding in crop plants. For carotenoid content among crop plants, maize and tomato are best studied by this technique. Because there is interest in accumulation of various intermediate products in the pathway as well as end products, QTLs were developed for genetic determinates that are not independent of each other. Some QTLs affect multiple pigment contents. 

Berset, C. and Caniaux, R, Relationship between color evaluation and chlorophyllian pigment content in dried parsley leaves, J. Food Sci., 48, 1854, 1983. 

The pH differential method was described as a fast and convenient assay for the quantitation of monomeric anthocyanins by Giusti (2001). It was approved by the Association of OfQcial Analytical Chemists (AOAC) in 2005 as a standard method to evaluate total monomeric anthocyanin pigment content in fruit juices, beverages, natural colorants, and wines. The degradation index is the ratio between total and monomeric anthocyanins (Table 6.3.1). The content of total anthocyanins can be obtained by the single pH method and the monomeric anthocyanin by the pH differential method. ... 

Lee, J., Durst, R., and Wrolstad, R., AOAC official method 2005.02 total monomeric anthocyanin pigment content of fruit juices, beverages, natural colorants, and wines by the pH differential method, in Official Methods of Analysis of AOAC International, Horowitz, H., Ed., AOAC, Washington, D.C, 2005. 

Until 2004, no betalain standards were commercially available and current products lack the required purity. Preparative isolation from plant material is laborious and costly and the resulting standard substances vary in relative humidity, crystal water, and salts, resulting in over- or under-estimation of pigment contents... 

Due to varying solvent systems, varying purities and water contents of purified pigments, different molar extinction coefficients have been reported." - - The most reliable ones commonly applied are 60,000 L/mol cm for betanin, 56,600 L/mol cm for amaranthin, and 48,000 L/mol cm for betaxanthins. ° Pigment contents may be calculated with the following formulae." - ... 

Huang, L. and A. Haug. 1974. Regulation of membrane lipid fluidity in Acholeplasma laidlawii Effect of carotenoid pigment content. Biochim. Biophys. Acta 352 361-370. 

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