Colorants, food perception

Food colorants play an important role in quality perception. Color is often the first notable characteristic of a food and it influences the expectations of consumers buying the product and also influences food handlers who make quality-related decisions, for example, during visual inspections." More specifically, color predetermines our expectations and perceptions of flavor and taste. " Color is interrelated with flavor intensity (detection threshold), with sweetness and salinity sensations, and also with our susceptibilities to and preferences for products. For example, consumers perceived a strongly red-colored strawberry-flavored drink to be sweeter than a less colored version, and yellow was associated with lemon and pink with grapefruit, but by reversing the colors, flavor perception changed." If food color is not appealing, consumers will not enjoy the flavor and texture of the food. ... 

J. Walford, ed.. Developments in Food Colours, Vols. 1 and 2. Elsevier AppHed Science, London, 1980 and 1984. Includes chapters on synthetic and natral food colors used in the United States, and on the influence of color on the perception and choice of food. 

With regard to choice and consumption of food, all human sensory perceptions are involved. Among them, vision is the most important one for selecting food and appreciating its quality. Color is an intrinsic property of food. A color change of food often is caused by a quality change. Consumers are attracted by the color of a food product. This imphes three main consequences for food producers ... 

In the preceding section, we presented principles of spectroscopy over the entire electromagnetic spectrum. The most important spectroscopic methods are those in the visible spectral region where food colorants can be perceived by the human eye. Human perception and the physical analysis of food colorants operate differently. The human perception with which we shall deal in Section 1.5 is difficult to normalize. However, the intention to standardize human color perception based on the abilities of most individuals led to a variety of protocols that regulate in detail how, with physical methods, human color perception can be simulated. In any case, a sophisticated instrumental set up is required. We present certain details related to optical spectroscopy here. For practical purposes, one must discriminate between measurements in the absorbance mode and those in the reflection mode. The latter mode is more important for direct measurement of colorants in food samples. To characterize pure or extracted food colorants the absorption mode should be used. 

Nevertheless, a mutual understanding about colors does work because conunon rules have been implemented by education, habituation, socially approved behavior, and properties that appear to individuals simultaneously, e.g., the vertical signal order of traffic lights. However, those rules are of limited value when color perception is the base for aesthetic appreciation as is the case for many industrial products and food products. In order to meet the demands of as many consumers as possible, producers look for a standard consumer who is most representative of the group. This requires establishment of a reliable measurement procedure that can be reproduced easily and be adapted to the various conditions under which it is applied light conditions, more or less opaque or translucent objects, object surface structures, etc. These measurement procedures were created more than a century ago and have... 

Food quality management aims to realize food quality that complies with or even exceeds customer or consumer requirements. Food quality is not only affected by intrinsic properties and applied technological conditions, but is also influenced by the people who design, control, improve, and assure food quality. While the emphasis of previous chapters is on providing insights into the physics, chemistry, biochemistry, and perception of food colorants, this chapter illustrates the importance of this fundamental knowledge and information for food quality management. 

First, a food quahty relationship model has been developed. It considers food quahty (FQ) to be dependent on food behavior (FB) and human behavior (HB). FB is a function of food dynamics (FD) (such as variable pigment concentrations and differing color degradahon prohles) and apphed technological conditions (TCs) (such as oxygen control to maintain color concentrahons). Likewise, HB is a function of human dynamics (HD) (for example, varying color perceptions due to age differences), and administrative conditions (ACs) (such as use of color cards to support visual color inspection). These relations are reflected in the food quahty relationship model as ... 

Color is the most obvious characteristic of a food and often predetermines the quality expectations and perceptions of consumers and food handlers who judge food. Color may provide the key to cataloging a food as safe based on good aesthetic and sensory characteristics (Section 7.1.1). A profound understanding of the physical and chem-... 

ORGANOLEPTIC. A term widely used to describe consumer testing procedures for food products, perfumes, wines, and the like in which samples of various products, flavors, etc. are submitted to groups or panels. Such tests are a valuable aid in determining the acceptance of tlie products and thns may be viewed as a marketing technique, They also serve psychological purposes and are an important means of e valuating the subjective aspects of taste, odor, color, and related factors, The physical and chemical characteristics of foods are stimuli for the eye, ear, skin, nose, and mouth, whose receptors initiate impulses that travel to the brain, where perception occurs. 

There has been a growing interest in the food industry for a color space based on a polar model. In 1976 when CIELAB was adopted, the CIE recommended an alternative color scale known as CIELCH or L C H. Of the three dimensions of color, the hue is the most critical in terms of perceptibility and acceptability for normal color observers. The L C H color space identifies the hue as one of the three dimensions. A color is located using cylindrical coordinates with L being the same as in CIELAB and C and H computed from a and b. The coordinates of CIELCH (also see Fig. F5.1.11) are ... 

There are other distinctions from mescaline. Unlike mescaline or Peyote, there is rarely any body discomfort during the early phase of intoxication, no nausea and only an occasional comment suggesting hyperreflexia. And, also unlike mescaline, most subjective reports on ME claim that music produces little imagery, and the exaggeration of color perception is more reserved. Appetite is normal, the tastes and textures of food are unusually rewarding. No subject has ever expressed a reluctance to repeat the experience. Sleep is easy, refreshing, and the following day seems free from residue. 

The structures of some prominent d,v-isomcrs of lycopene are shown in Figure 4.2. G. s-isomers have distinct physicochemical characteristics (and hence, bioactivity and bioavailability) compared to their all-trans counterparts. In general, the di-isomers are more soluble in oil and hydrocarbon solvents than their all-trans counterparts. They are less prone to crystallization because of their kinked structures. They also are less intense in color, which may influence the consumers perception of food quality. The appearance of a distinct absorption maximum in the UV region ( di-peak ) is useful for distinguishing between the different isomers. 

All the methods described are invasive techniques that are time consuming and often expensive. To reduce sampling and analytical costs, and to speed up the analyses, noninvasive analytical procedures have been developed with the aims to characterize the pigment content of samples and, in the case of food products, to estimate the impact of a color change on the visual perception of the product. 

Blendford, D. 1995. Colouring consumers perceptions. Food Ingredients Analysis Int. 17, 10-11. Borrelli, G.M., Troccoli, A., Di Fonzo, N., and Fares, C. 1999. Durum wheat lipoxygenase activity and other parameters that affect pasta color. Cereal Chem. 76, 335-340. 

The color measurement of fried foods is traditionally done either instrumentally or visually through trained panelists. Human evaluation is quite subjective, tedious, and subject to error of perception. Hence, it is least recommended for the color determination of fried foods. The instrumentation procedure involves the use of color spaces and numerical values to create, visualize, and represent color in 2D and 3D spaces (Trusell et al., 2005). Food color is usnally measured using the L a b color indices. This is the international standard color measurement technique, adopted by the Commission Internationale d Eclairage (CIE) in 1976. L is a measure of luminance or lightness on a scale of 0-100, a is a measure of greenness to redness, and b is a measure of blueness to yellowness. This technique provides measurement similar to how human eye perceive colors (Hunt, 1991). 

The radiolysis of food constituents leads to minor but sometimes perceptible changes in sensory qualities associated with the net formation or degradation of a specific constituent. Color, texture, and rancidity are qualities that can be affected either during irradiation or subsequent storage, depending on the food, the atmosphere, the packaging, and the irradiation dose and temperature. Often, there are implications in the radiation chemistry for ensuring optimal quality of irradiated meat products. 

The presence or activity of water in foods may also enhance the rate at which deteriorative chemical reactions occur. Some products may become rancid through free radical oxidation even at low humidities and thus become unacceptable. Labile nutrients such as vitamins and natural color compounds are oxidized more rapidly when stored at low moisture levels. Enzyme-mediated hydrolytic reactions may reduce the quality of the food product. Other reactions such as the Maillard type of nonenzymatic browning may be enhanced by the presence of higher levels of water. On the other hand, water content is crucial for the textural characteristics and the sensory perception of foods. A food may be found unacceptable by consumers simply because it does not satisfy their textural (sensory) anticipation. 

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