Colors meet their match in ingredient testing lab

Prepared Foods, April, 1989

Colors meet their match in ingredient testing lab

Consumers today demand consistency in the products they buy. Often they see a color change in processed food as a sign that flavor or quality has also changed. The color of a product, whether appealing or unappealing, may influence consumers' purchasing decisions.

To maintain consistency, food manufacturers must closely monitor the colors they use. Manufacturers of food colorings need to maintain an accurate and efficient staff of experienced specialists and sophisticated color measurement equipment to ensure that the final product meets the food manufacturer's and, finally, the consumer's standards.

Chr. Hansen's Laboratory (Milwaukee, Wis.) manufactures natural food flavors and colors. The company uses turmeric, paprika, annatto, and beet color extracts to make food colorings for a variety of dairy-based products, candies, bakery fillings, beverages, sauces and crackers.

When coloring or changing the color of a food product, Hansen's specialists compare a sample product against the desired product--for example, a client's cracker against his competitor's cracker--to determine how close the color of the sample is to the desired color. Traditionally, this comparison was dependent upon the specialist's visual accuity and experience. Chr. Hansen's has improved its color matching abilities by using a HunterLab LabScan II spectrocolorimeter.

The LabScan II allows the color specialist to simulate a visual comparison electronically. The instrument's unique optical sensor illuminates the product sample at a 0 degree angle, uses a sixteen-station fiber optic viewing ring to collect light reflected from the sample at 45 degrees, then averages the input from all stations. This process simulates the human synthesis of the red, green, and blue responses of the eye/brain. The Lab Scan quantifies these responses in numerical units called tristimulus values.

"By using the Hunter, we eliminate, somewhat, any debate (about product color), because we're working with a numerical system," says Chr. Hansen's senior color development specialist Raymond Sell.

At Chr. Hansen's, when a color specialist is given two products (a sample of the client's current product and a standard to which it must be matched), the first step is to gather all known information about the products' contents. Then both samples are measured with the LabScan to make a of tristimulus values.

The spectrocolorimeter's computer analyzes the data with a user-specified color scale. It can provide both a screen display and hard-copy documentation of the results--in this case, tristimulus values. Chr. Hansen's specialists use the LabScan's color difference display to show numerical CIE 1976 L*a*b* (CIELAB) values for the sample and standard, as well as a verbal explanation of the difference.

"We generally use the L*a*b* scale," says Sell, "because it is slightly more accurate for yellows and oranges than other scales, and most of our products tend toward these colors."

The LabScan's computer can translate a single physical reading into a number of different tristimulus scales, eliminating the need to re-measure the sample for each scale.

These measurements provide color specialists with the information they need to accurately predict the type and concentration of colorings needed to match the standard. When a new sample is created, the color specialist uses the LabScan to compare it to the standard, until an acceptable match is reached.

The LabScan system uses a tungsten-halogen lamp filtered to simulate D65 daylight; however, its software enables the user to obtain readings based on A, C, F2 and Phillips TL84 illuminants, as well. This satisfies the need to compare products under different light sources, since some colors may appear to match under one type of light, but not match under another, a phenomenon known as metamerism.

"Addition of the LabScan II has definitely been time-saving in trying to match colors, especially under different lighting," says Sell.

In describing another time-saving feature of the LabScan, Sell notes: "We're working on one product that we had worked on roughly four or five months ago, and we still have the standard stored in the instrument. It saved us from having to make up and measure another standard."

Adding HunterLab's spectrocolorimeter has helped Sell streamline his operations and guarantee consistent, high-quality products. By working with precise measurements, Hansen's has saved time and money in developing new colors.

PHOTO : Chr. Hansen's Laboratory uses the LabScan II to objectively measure colors and match sample food products to desired standards. The company manufactures food colorings to meet customers' specific application needs.