The color of a food or beverage is one of the most important aspects of its overall perception. The following Prepared Foods’ R&D Seminars discuss methods for measuring food color, as well as uses for beta-carotene, certified-organic colors and caramel colors.
Measuring the Color of Foods January 2012/Prepared Foods -- Color affects many different things in people’s lives. It can affect mood and how different items are perceived. Colors are used to indicate something is potentially dangerous, such as the red stop sign. For this reason, it is imperative food processors be able to accurately measure color, since products or packages that fail to meet expected colors may be rejected by the consumer. Because the food processing industry is a business that relies on customer loyalty and repeat purchases, a failure to detect an issue related to color can cost a processor a great deal of money.
Color is defined as the quality of an object with respect to the amount of light transmitted through or reflected from it. For someone to perceive colors, three things are needed: a light source; an observer (i.e., the consumer); and the object in question, explained Fritz Baltutat, senior sales advisor, Konica Minolta, in his presentation, “Measuring the Color of Food,” given at the Prepared Foods’ R&D Applications Seminar-Chicago in 2010. The visible spectrum of light is very narrow. The visible colors range from red to violet, with all the different hues in between. To help people better understand the colors in the visible spectrum, the acronym ROY G BIV has been used for many years: red, orange, yellow, green, blue, indigo and violet.
When measuring color, there are different tools that can be used. There are subjective evaluations, in which people do a visual assessment, and objective measurements using instruments. People are the final arbiter of color, but when it comes to evaluations, there are distinct limitations, explained Baltutat. Men and women may perceive colors differently. Or, age, fatigue and other factors can affect color perception. Instruments are used to quantify colors, because, if properly calibrated, they are consistent and will measure colors the same way or detect small differences between test samples. As noted above, part of the equation for evaluating colors is lighting. Modifying a light source can change the colors. For example, continued Baltutat, sensory scientists will often use colored lights to mask differences in a food’s color, if they want to eliminate a potential bias food color could impart.
In the food processing industry, proper measurement of color can enhance quality and productivity; reduce operating costs; ensure consistency from batch to batch; and improve customer satisfaction. The two instruments used for color measurement are colorimeters and spectrophotometers. Colorimeters are used for quality-control activities. They are used to measure color differences and are generally used to determine whether a sample is acceptable or not. Spectrophotometers are more versatile and of greater sensitivity than colorimeters. They measure both reflected light and light that is transmitted through a liquid or clear film. This instrument will also generate spectral data. Colorimeters are less expensive than spectrophotometers, but unlike spectrophotometers, they are not a good research tool. This instrument allows researchers to communicate color in what is known as the three dimensions of color: lightness (L); redness to greenness (+a to –a); and yellowness to blueness (+b to –b). Lightness is measured on a scale of 0-100. This allows potential users to accurately define color and acceptable tolerances. Tolerances are best determined as follows:
1. Visually using controlled lighting by committee or by the customer and supplier.
2. Set as wide as possible at the start of the process and refined during development.
3. Tested using products at the outer limits, to determine what is really acceptable to consumers.
4. Measure acceptable products to come up with meaningful tolerances in regards to specifications.