Color expectation

Color expectation ia food depends also on how well estabhshed the color of that food is and how closely its color is associated with its quaUty. 

In a given vehicle, kn, sn, KB, and SB can be determined by calibration against reference systems. Thus K and. S, and then R, can be calculated. If this is done for all wavelengths needed in the computation of X, Y, and Z values, then X, Y, Z, and thereby the color expected for the pigmented system can be calculated. 

This was demonstrated in a pioneering worlc of Ferraris and colleagues in 1999, who correlated the observed color coordinates of polymer blends, copolymers, laminates, and patterns with the colors expected from colorimetric theory. The goal was to evaluate the direct steady relationship between color and chemical composition. Color coordinates of laminafes and patterns were predicted quite accurately predicted colors deviated significantly from the observed color coordinates in case of blends and copolymers. 

The final step in the denitrification process is carried out by the soluble enzyme nitrous oxide reductase (NoS). This enzyme has been isolated from a number of sources, and is unusual in a number of ways. In most cases, it is a homodimer of ca. 74 kDa subunits with ca. 4 Cu/subunit, but the enzyme is bright purple or pink as isolated, depending on conditions, and becomes the typical blue color expected for copper proteins only after reduction with dithionite. A variety of spectroscopic studies strongly suggest that the enzyme contains at least one mixed-valent, thiolate-bridged Cu(l)—Cu(ll) unit that may well be similar to a binuclear copper center in cytochrome c oxidase (23). The reaction catalyzed by the enzyme is deceptively simple ... 

Titration curve for 50.00 ml of 0.100 M CH3COOH with 0.100 M NaOH showing the range of pHs and volumes of titrant over which the indicators bromothymol blue and phenolphthalein are expected to change color. 

Titration curves for 10 M Mg + with 10 M EDTA using calmagite as an indicator at (a) pH = 9, (b) pH = 10, and (c) pH = 11. The range of pMg and volume of titrant over which the indicator is expected to change color is shown for each titration curve. 

Nonnutrient Additives. Nonnutritional dietary additives provide antioxidants to preserve freshness, flavor enhancers to stimulate food selection, color to meet the owner s expectations, pellet biaders to minimi2e fine particles, mycostats to minimi2e mold growth, and iagredient-flow enhancers. Pet foods do not iaclude coccidiostats, antibiotics, added hormonal materials, and fly-larval iasecticides used ia other animal feeds. 

A food must have the expected or proper appearance and color before it will be readily consumed (7). There are many prepared foods in which artificial flavors and colors are used whose flavor is sufticientiy bland to make color essential for flavor identification, eg, margarine. The preservation of color in natural food during processing or the development of color by processing are aspects of primary importance in food acceptance. 

The level of technical service support provided for a given product generally tracks in large part where the suppHer considers thek product to be located within the spectmm of commodity to specialty chemicals. Technical service support levels for pure chemicals usually provided in large quantities for specific synthetic or processing needs, eg, ammonia (qv), sulfuric acid (see SuLFURic ACID AND SULFURTRIOXIDe), formaldehyde (qv), oxygen (qv), and so forth, are considerably less than for more complex materials or blends of materials provided for multistep downstream processes. Examples of the latter are many polymers, colorants, flocculants, impact modifiers, associative thickeners, etc. For the former materials, providing specifications of purity and physical properties often comprises the full extent of technical service requked or expected by customers. These materials are termed undifferentiated chemicals (9),... 

Specialized training is an absolute requirement for technical service personnel. A typical example is a person involved in supporting a polymer for which the use is the manufacture of rotationaHy molded consumer products. The technical service person is expected to be reasonably familiar with topics such as polymer rheology evaluations, gel-permeation chromatography, rotational mol ding, color science, regulatory requirements for use, mechanical and photochemical behavior of the pigmented polymer, optics, and so forth. Expertise of this variety caimot be expected to be obtained without careful... 

Most staple foods such as meat, white bread, potatoes and other vegetables, and most fmits are not artificially colored siace their natural appearance is perfecdy acceptable. Foods are usually colored because they have no natural color of their own, because their natural color was destroyed or drastically altered as a result of processiag or storage, or because their color varies greatly with the season of the year or their geographic origin. Thus, colorants are added to foods to make them appear the way the customer wants and expects them to appear. 

Consumers expectations depend on several factors including cultural background, past experiences, desire for color coordination, esthetic appeal, local customs, fads, etc. Thus, eg, a Texas red hot sold ia the South is often colored quite differently than one sold ia the North, Midwesterners prefer butter with a deep yellow color, and on birthdays the decoration on a boy s cake are often blue and those on a gid s are often pink. 

Although the EEC is stiU in the process of completing cosmetic regulation, the final directive is expected to require member states to ban marketing of cosmetics that contain prohibited ingredients, an amount of a substance in excess of that proscribed, coloring agents, preservatives, or uv filters not specifically allowed. 

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