Beta-carotene is typically used in food products as a coloring agent. The coloring of food products enhances the perception of such products as appealing to consumers. However, it is known that beta-carotene is degraded through oxidation with consequent loss of its coloring properties. Antioxidants are often combined with beta-carotene to counteract this degradation for a period of time commensurate with the shelf life of the food products.
The antioxidants effective for oil or fat-based foods are typically different than antioxidants used for water-based, or very high moisture content foods. The antioxidants approved in the United States for use in foods include, among others, ascorbic acid, ascorbyl palmitate, BHA, BHT, citric acid, EDTA, erythorbic acid, gum guaiac, lecithin, phosphates, propyl gallate, sulfites, tocopherols, glucose oxidase, dilauryl thiodi-propionate, THBP or 2,4,5-trihydroxybutyrophenone, and TBHQ or 4-hydroxymethyl-2, di-tert-butylphenol.
Choice of an antioxidant in an oil or fat-based system depends on several factors including the desired function, dispersibility, storage conditions, and possible imparted flavor.
Ascorbyl palmitate and/or dl-alpha-tocopherol have been specifically used to stabilize foods colored with oil dispersions of synthetic beta-carotene, especially in colored oils. Examples of these combinations are disclosed in Cort, WM 1974, J AM Oil Chem Soc: 51; 321, and, U.S. Pat. No. 4,504,499.
Oil-dispersible beta-carotene is not typically used in dry food mixes because water soluble forms are easier to handle. However, production constraints may not allow for the incorporation of powdered beta-carotene in dry or wet blending operations. When using dry mixes, oil-soluble beta-carotene may have to be adsorbed onto one of the dry ingredients, thus imparting concentrated color. Typically, powders consisting of finely divided particles such as sucrose, glucose, or extra fine powders are used as an adsorbate. Herein all discussions refer to the use of the oil-dispersions of beta-carotene.
When adsorbed onto a dry ingredient, beta-carotene is typically distributed over the surface of the particles of the dry ingredient thus exposing a large cumulative surface area to oxygen and light. This typically results in increased degradation of the beta-carotene causing color loss.
In order to prevent the degradation and resulting color loss of the beta-carotene, it is typically necessary to add an antioxidant. An antioxidant of choice is a tocopherol such as dl-alpha-tocopherol since the tocopherols are naturally occurring substances. However, it is known in this art that tocopherols are not recognized as having good antioxidant properties, especially when used as the only antioxidant.
Much of the literature states that tocopherols have a weak to moderate antioxidant effect (Reinton, R. J Food Sci 1981: 46; 970), and that in fact, gamma-tocopherol may be more effective than alpha-tocopherol (Sherwin, ER, J Am Oil Chem Soc. 1976: 53; 430).
Cort (Am Oil Chem Soc, 1974: 51; 321) explains that above 0.02% in animal fats tocopherols are not effective antioxidants. Added tocopherols used to stabilize vegetable oils are not very effective at preventing rancidity because of residual natural tocopherols in the oil. It has been found that ascorbyl palmitate used as an antioxidant in vegetable oils is much more effective singly, as well as synergistically, with tocopherols, than the use of tocopherol alone.
What is needed in this art are food coloring compositions containing beta-carotene which have improved color stability.