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.
Color and color perception are integral parts of the food industry. Part of the product development process is to determine what colors or ranges of colors are acceptable to consumers and, then, to formulate the products to meet those criteria. Being able to properly measure color during the development and as part of quality operations is essential to ensure customer satisfaction. Selecting the right instruments to do this work is critical to the health and continued growth of the business.
“Measuring the Color of Food,” Fritz Baltutat, senior sales advisor, Konica Minolta, firstname.lastname@example.org, http://konicaminolta.us
—Summary by Richard Stier, Contributing Editor
Beta-Carotene for Color and Health
Beta-carotene is a unique compound. It is an excellent source of vitamin A; acts as an antioxidant; imparts color to foods; and may be used to enhance the nutrition of a wide range of foods. Beta-carotene may be produced from several different sources. It can be chemically synthesized, produced through fermentation, extracted from algae or extracted from palm oil. The composition of beta-carotene from these different sources varies significantly. That produced synthetically contains approximately 98% trans beta-carotene; the fermented product 94%; that from algae 64%; and that from palm oil 41%.
During a 2010 Prepared Foods’ R&D Applications Seminar presentation titled, “Beta-carotene for Color; Beta-carotene for Health,” Dale Bertrand, Technical Services, Farbest Foods, examined each of the functions of beta-carotene. Nutritionally, it is an essential and safe source of vitamin A, which is found naturally in orange vegetables, such as carrots and sweet potatoes, and in leafy greens, such as spinach. Utilization of beta-carotene from these sources is not efficient, according to Bertrand. Supplements are recommended for this reason. The amounts used as a colorant or in a nutritional supplement are sufficient to meet the needs of the human body. Both the natural and synthetic may be used to this end.
Beta-carotene is an excellent antioxidant. Antioxidants neutralize harmful free radicals in the body. Free radicals are highly reactive and energized molecules that may form through exposure to ultraviolet light or via different biochemical pathways in the human body. These compounds have been linked to the development of pre-cancerous changes in cells and may damage lipids in cell membranes and genetic material in cells, which may also lead to the development of cancer.
Beta-carotene is also a colorant. It can produce colors ranging from brick red to yellow, depending upon concentration. A level of 50ppm will produce a pale yellow color, whereas 3,000ppm will yield an orange hue. Beta-carotene is available in different forms for use in foods. It is available as a powder; beadlets with 10 and 20% beta-carotene, respectively; oil suspensions of different concentrations, ranging from 10-30%; and 1 and 2% emulsions, respectively, expounded Bertrand.
Each of these forms has different product applications, Bertrand explained. Powders may be used in water-based foods, such as bakery mixes, puddings, milk products, instant products and confectionery products. The powdered products have excellent dispersibility and bioavailability. Beadlets may be used for beverages, water-based foods, instant puddings, confectionery and milk products. Like the powders, these have excellent dispersibility and bioavailability. Oil-based beta-carotenes may be used for fortification and coloring of products, such as margarines, cooking oils, popping oils, food flavoring and color systems, and gelatin capsules. The target level for fortification is the 15,000IU (International Units) mandated by the FDA. Both beta-carotene beadlets and emulsions are used for dietary supplements, in hard- and soft-shell capsules, soft gel capsules and different food products. The encapsulated beadlets have excellent stability. Encapsulation helps protect the product from oxidation and enhances its ability to be used in foods, as it is free-flowing.
Beta-carotene is an extremely versatile compound. It acts as a colorant, an antioxidant and a nutritional supplement. The product is available in different forms—powder, encapsulated beadlet, emulsion and oil suspension—allowing it to be utilized in a wide range of products and processes. Which form is chosen and how it is used depends upon the application.
Applications of Select Certified-organic Colors
According to Fergus Clydesdale, Ph.D., from the University of Massachusetts, “Color plays a key role in food choice, by influencing taste thresholds, sweetness, perception, food preference, pleasantness and acceptability.” Consumers look at how foods are colored and expect certain flavors, explained Glen Dreher, Ph.D., global applications scientist, D.D. Williamson, during a presentation titled, “Applications of Select Certified Organic Colors,” given at Prepared Foods’ 2011 R&D Applications Seminar-Chicago. As an example, coloring a lemon ice purple will “trick” many into believing they are actually consuming a grape product.
One product group that has grown by leaps and bounds over the past 20 years is organic foods, he continued. The USDA has established guidelines defining organic foods. The 1990 law established four levels, which are: products labeled “100% organic,” which must be made with 100% organic ingredients, excluding water and salt; products labeled as “organic” must consist of at least 95% organic ingredients, excluding salt and water; products labeled “made with organic ingredients,” which must contain at least 70% organic ingredients and list up to three organic ingredients on the principal display panel; and, finally, products containing less than 70% organic ingredients. The latter cannot use the term “organic” anywhere on the label.
Many consumers believe organic foods are healthier, safer and better-tasting, even though the scientific evidence does not definitively support such a belief. The United States National Organic Program (NOP) includes provisions in the regulation that allow non-organically produced agricultural products in or on processed foods labeled as organic. This may be found in section 205.606 of the document. This allows for the use of 19 colorings derived from agricultural products. These colorings are: annatto extract color, beet juice extract color, beta-carotene extract color, black currant juice color, black/purple carrot juice color, blueberry juice color, carrot juice color, cherry juice color, chokeberry (Aronia) juice color, elderberry juice color, grape juice color, grape skin extract color, paprika color, pumpkin juice color, purple potato juice, red cabbage extract color, red relish extract color, saffron extract color and turmeric extract color. These were added to the list, because there is a limited supply of certified-organic colors and to help ensure organic foods will be competitive, explained Dreher. This list is subject to review on a regular schedule, under the sunset review process.
There also are a number of certified-organic colorings available for use. These include annatto, caramel and anthocyanins. Annatto is found in the outer layer of the seeds of a tropical plant (Bixa orellana). Annatto is used when the desired shades are yellow to orange. Like all colors, there are products and processes for which it may be used effectively. Annatto has fair stability when exposed to light; good heat stability; and is most effective when used in products with pH values of 4.0-7.5, which covers a wide range of foods. Among the applications for annatto are processed cheeses, snacks, ice cream and yogurt, salad dressings, fats and oils, frostings and breakfast cereals. Current forms available for organic annatto are not effective in products with a pH lower than 4.0 and, thus, are not a good option for most beverages.
Certified-organic caramel colors may be produced from certified-organic cane sugar, which ensures they are not associated with genetically modified ingredients. Caramel colors, which impart brown color to foods, have many applications. They include beverages, tea, dressings, balsamic vinegar and snack foods.
Another group of organic colors are certain anthocyanins, such as purple corn. They impart foods with an orange-red hue and are very heat-stable. Unfortunately, applications are limited, given they perform best at pH values lower than 3.5.
—Summary by Richard Stier, Contributing Editor
In Title 21, Part 73.85 of the Code of Federal Regulations (CFR), caramel is defined as the dark brown liquid or solid material resulting from the carefully controlled heat treatment of the following food-grade carbohydrates: dextrose, invert sugar, lactose, malt syrup, molasses or starch hydrolysates, and fractions thereof. The CFR further states the food-grade acids, alkalis and salts listed in this subparagraph may be employed to assist in caramelization, in amounts consistent with good manufacturing practice.
Liquid caramel is produced using the materials mentioned above and processing them in a pressure vessel to develop the color. The resulting caramel is then passed through a flash tank, filtered and stored until needed. It may be sold as a liquid product or further processed by atomizing and drying into a powdered product.
The primary quality tests done on the product include color strength, specific gravity and pH, said Terry L. Geerts, application chemist, Sethness Caramel Color, during his presentation titled, “Using Colors,” given at Prepared Foods’ 2010 R&D Applications Seminar-Chicago. Additional tests are viscosity, hue index, resinification, haze and gel tests, alcohol solubility, salt solubility, the beer test and neutral tannin test. Processors will retain samples of each lot that is manufactured.
There are four commercial classes of caramel. These are:
• Class I – No ammonia or sulfite reactants.
• Class II – Sulfite reactants, but no ammonia.
• Class III – Ammonia reactants, but no sulfites.
• Class IV – Sulfite and ammonia reactants.
Class I caramel, or plain caramel, is produced by heating carbohydrate acids or alkalis to control pH, Geerts said. There are no added ammonium or sulfite salts. The end-product has a strong aftertaste and a mild aroma. Typical applications include whiskeys and liquers, lemonade products, coatings for poultry, juice concentrates, sauces and as a cocoa extender.
The product is used at a range of 0.1-30%, depending upon the application. Of all the caramel products, this is the most natural. Its color strength is weaker than the other classes, but it has excellent application where alcohol solubility is a requirement.
Class II products—which, as noted above, are manufactured with sulfites, but no ammonia—have a mild flavor and aroma profile. These products do, however, have a strong negative charge. Typical applications include wines, rum, liqueurs, brandy, light cake mixes, coatings for poultry and snack foods. In foods and beverages, the Class II caramels have an excellent red color. Usage rates are the same as the Class I products—0.1-30%.
Class III products have a positive charge and have a flavor profile that ranges from coffee to chocolate. There are coffee notes in the aroma. This product is reacted with ammonia, but no sulfite is used. Class III caramel colors are used in cereals, brewing, meat sauces, cooking and dipping sauces, soups, pet foods, bakery products, licorice and many more applications. It is an extremely versatile color. Usage rates range from 0.4-30%, depending upon the application.
Class IV products—the final category of caramel colors—are the most commonly used. They have a negative charge; a mild flavor profile; and a bland aroma—thus, they will not significantly impact the taste or aroma of the finished product. These caramel colors are used in colas and other soft drinks, baked goods, meat rubs, seasoning blends, pet foods, soups, flavorings, cocoa extenders, coffee products and syrups. The amount used generally ranges from 0.2-30%. Class IV products are even more versatile than the Class II products, explained Geerts.
Caramel colors are extremely adaptable and may be used to replace other colorants. The usage and product selected depends upon the application. Work with a supplier to ensure the proper product is selected. pf