The natural pigments of many food are unstable in hear or oxidation. Thus, storage or processing can lead to variation in color even when the nutritional value remains unchanged. Changes in the appearance of a product over time may cause consumers to that a bad or an adulterated product has been purchased, particularly in light of highly publicized incidents of product tampering. The use of food coloring can resolve this problem for retailers and manufacturers. Ripe olives, sweet potatoes, some sauces, and syrups, as well as other foods, are colored mainly to ensure uniformity and consumer acceptability.