Since extracts are produced from biological materials that can be highly variable, the color of one manufactured lot may be different from a previous lot of the same product.
An extract’s color comes from the pigmentation found in the source materials, which can vary significantly between lots. Since an extract’s color has not been shown to affect its allergenicity, nor is there a “typical” color for each extract, this is not a variable that is screened for during quality testing.
For example, certain raw materials, such as Johnson grass, tend to show significant color variation between lots, with some appearing light yellowish green and others appearing very dark. Since Johnson grass is a component of a number of stock mixes, this variation will affect the color of the mix as well.
Allergenic proteins extracted into solution should be invisible. Therefore, conclusions can not be made about an extract’s potency or identity based on its color or visual characteristics. The exception to this is the presence of Precipitation.
If you have any questions regarding the color of your extracts, please contact your allergen extract supplier for assistance.