Analysis of Color in Foods
Laboratory 4: Analysis of Color in Foods
1. Introduction:
The purpose of this experiment is to use various forms of color analysis to evaluate the quality of commercial food samples. Color and appearance of foods is an important criterion that consumers consider when buying foods and contributes to the overall quality of a product.
One way to visually perceive color is through the Munsell system. This widely used visual color-ordering system sorts the visual system into three parts: hue, value and chroma. Hue refers to five principle colors: red, yellow, blue, green and purple. It also includes five intermediate colors: Yellow-red, green-yellow, blue-green, purple-blue, and red-purple. Value refers to the lightness and darkness of the hues, where dark colors are at the bottom and light colors at the top. Chroma is the saturation of the color and the center of the wheel is the least saturated. All together, these three dimensions formulate a color description.
One instrumental measurement of color used internationally is the Commision Internationale on Illumination (CIE). The CIE developed standard illuminants for color measurements to objectively measure color: a tri-stimulus color system that uses numerical values X Y and Z to represent the amounts of red, green and blue primaries in a spectral transmission. X and Y coordinates from a sample can then be plotted on a chromaticity diagram and used to find % purity and dominant wavelength. The dominant wavelength is analogous to hue in the Munsell system and the distance of the object coordinates from white light is the %purity (Nielsen, 2010).
The Agtron E-5 colorimeter measures the green/red ratio in samples. Generally, the redder a sample is the lower the Agtron’s reading (Mitchell, 2014).
The Macbeth light box, which uses two spinning USDA Grade A and Grade C standards, can compare and evaluate samples with a score on the USDA scale. These discs, which have a combination of Munsell colors,
1. Introduction:
The purpose of this experiment is to use various forms of color analysis to evaluate the quality of commercial food samples. Color and appearance of foods is an important criterion that consumers consider when buying foods and contributes to the overall quality of a product.
One way to visually perceive color is through the Munsell system. This widely used visual color-ordering system sorts the visual system into three parts: hue, value and chroma. Hue refers to five principle colors: red, yellow, blue, green and purple. It also includes five intermediate colors: Yellow-red, green-yellow, blue-green, purple-blue, and red-purple. Value refers to the lightness and darkness of the hues, where dark colors are at the bottom and light colors at the top. Chroma is the saturation of the color and the center of the wheel is the least saturated. All together, these three dimensions formulate a color description.
One instrumental measurement of color used internationally is the Commision Internationale on Illumination (CIE). The CIE developed standard illuminants for color measurements to objectively measure color: a tri-stimulus color system that uses numerical values X Y and Z to represent the amounts of red, green and blue primaries in a spectral transmission. X and Y coordinates from a sample can then be plotted on a chromaticity diagram and used to find % purity and dominant wavelength. The dominant wavelength is analogous to hue in the Munsell system and the distance of the object coordinates from white light is the %purity (Nielsen, 2010).
The Agtron E-5 colorimeter measures the green/red ratio in samples. Generally, the redder a sample is the lower the Agtron’s reading (Mitchell, 2014).
The Macbeth light box, which uses two spinning USDA Grade A and Grade C standards, can compare and evaluate samples with a score on the USDA scale. These discs, which have a combination of Munsell colors,