Coloration quality

In addition to the pigment concentration in the respective food source, the color quality is of major importance for plant material quality assessment and selection during production and storage. Color quality also strongly affects consumer purchase decisions. Since red beet is still the sole betalain source exploited commercially, quality parameters have been developed for beet preparations. The most important one is the so-called color shade representing a ratio of two absorbance values, namely for betaxanthins and for betacyanins, respectively, A (at 535 mn)/A (at 480 nm). 

Koskitalo LN and Ormrod DP. 1972. Effects of sub-optimal ripening temperatures on the color quality and pigment composition of tomato fruit. J Food Sci 37 56-59. 

Color quality This will be determined by the relative intensities of the various wavelengths of light emitted by... 

Heat is necessary to volatilize and excite the emitter, but you must not exceed the dissociation temperature of molecular species (or the ionization temperature of atomic species) or color quality wiU suffer. For example, the green emitter BaCl is unstable above 2000°C and the best blue emitter, CuCl, should not be heated above 1200°C [5]. 

In addition, the oxidizer must react with the selected fuel to produce a flame temperature that yields the maximum emission of light in the proper wavelength range. If the temperature is too low, not enough "excited" molecules are produced and weak color intensity is observed. A flame temperature that is too hot may decompose the molecular emitter, destroying color quality. 

To use potassium nitrate in colored flame mixtures, it is necessary to include magnesium as a fuel to raise the flame temperature. A source of chlorine is also needed for formation of volatile BaCl (green), or SrCl (red) emitters. The presence of chlorine in the flame also aids by hindering the formation of magnesium oxide and strontium or barium oxide, all of which will hurt the color quality. Shidlovskiy suggests a minimum of 15% chlorine donor in a color composition when magnesinm metal is nsed as a fuel [5]. 

The use of chlorate or perchlorate oxidizers (KCIO 3> KC10 , etc.) is one way to introduce chlorine atoms into the pyrotechnic flame. Another method is to incorporate a chlorine-rich organic compound into the mixture. Table 7.8 lists some of the chlorine donors commonly used in pyrotechnic mixtures. A dramatic increase in color quality can be achieved by the addition of a small percentage of one of these materials into a mixture. Shimizu recommends the addition of 2-3% organic chlorine donor into compositions that don t contain a metallic fuel, and the addition of 10-15% chlorine donor into the high temperature mixtures containing metallic fuels [11]. 

The pyrotechnic chemist always begins with a very small quantity of composition when carrying out initial experiments on a new formula. The preparation of one or two grams of a new mixture enables one to evaluate performance (color quality and intensity, smoke volume, etc.) without exposure to an unduly hazardous amount of material. 

The presence of incandescent solid or liquid particles in the flame will adversely affect color quality. The resulting "black body" emission of white light will enhance overall emission intensity, but the color quality will be lessened. A "washed out" color will be perceived by viewers. The use of magnesium or aluminum metal in color compositions will yield high flame temperatures and high overall intensity, but broad emission from incandescent magnesium oxide or aluminum oxide products may lower color purity. 

MgO particles is thereby reduced, and color quality improves significantly. 

Yellow flame color is achieved by atomic emission from sodium. The emission intensity at 589 nanometers increases as the reaction temperature is raised there is no molecular emitting species here to decompose. Ionization of sodium atoms to sodium ions will occur at very high temperatures, however, so even here there is an upper limit of temperature that must be avoided for maximum color quality. The emission spectrum of a yellow flare is shown in Figure 7.2. 

The mixture must ignite at a low temperature and continue to burn smoothly at low temperature (well below 1000°C). If the temperature is too high, the dye molecules will decompose and the color quality as well as volume of the smoke will deteriorate. Metal fuels are not used in colored smoke mixtures because of the high reaction temperatures they produce. 

The molecules creating the colored smoke must be of low toxicity (including low carcinogenicity). Further, they must readily sublime without decomposition at the temperature of the pyrotechnic reaction to yield a dense smoke of good color quality [3]. 

Conoco operated a stirred tank Pfaudler glass-lined reactor for the batch S03 sulfonation of detergent alkylate. The plant utilized over-the-fence S03 converter gas (8% S03 in dry air) having 6-8 h batch cycles (264). Allied Chemical Company provided details for batch S03 sulfonation (265,266) and Conoco also published their procedure for S03 batch sulfonation (267). Andrew Jergens Company patented a cyclic batch sulfonation and sulfation process introducing nondiluted S03 vapors into a venturi contacter that emitted reaction product into a stirred reservoir tank where it was recycled from the reservoir vessel through a heat exchanger and back to the venturi in the cyclic loop. The unit operated in a vacuum (268). Derived color quality was unspecified. 

Colorimetry relates the perceived color quality to the color stimulus, which in turn is based on the reflectance spectrum q (A). 

Wrolstad, R.E., Putnam, T.P., and Varseveld, G.W. 1970. Color quality of frozen strawberries Effect of anthocyanin, pH, total acidity and ascorbic acid variability. J. Food Sci. 35 448-452. 

Spectral methods are described for generating several color quality indices for wines. 

The accurate measurement of chlorophylls has importance for numerous reasons ranging from simple color considerations to medical research. The most practical of these is the assessment of fruit and vegetable color quality, as chlorophylls are known to degrade rapidly when subjected to thermal processing (Schwartz et al., 1981). However, interest has also been sparked by recent literature reports that point to the possible health benefits associated with chlorophyll consumption (Hartig and Bailey, 1998). 

Appearance The tablets should be examined for such problems as tablet mottling, picking of the monogram, tablet filming, and capping of the tablets. If the tablets are colored, the color quality needs to be examined. 

Color Dyes. Color quality is determined by the dyes chosen for the primary colors yellow, magenta, and cyan. Important parameters for subtractive color reproduction are peak wavelength, breadth of absorption peaks and the absence of secondary absorptions [11]. 

The degree of dispersion in a plastic system is of equal importance to a carbon black s physical properties in terms of color quality and other end-use properties. Dispersion, like color, is strongly influenced by carbon black morphology. Selecting... 

One method is adding color via concentrates or a masterbatch at the fabrication step (molding or extrusion). The process involves a two-component approach a natural polymer and a concentrated (solid or liquid) additive masterbatch metered and blended at the press. In this option, the fabricator must take responsibility for preblending the product, properly mixing and dispersing the two phases, and performing checks and adjustments to assure final color quality. 

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