Identifying Food Dyes with Spectrophotometers


A spectrophotometer is a specialized instrument that can be used to measure and quantify the reflectance and transmittance properties of a sample material. Among the many uses of spectrophotometers is in the food industry where many foods are colored using federally specified and approved food dyes. Because these food dyes have been given rigorous chemical inspection, they have many properties that are well documented and that can be used to easily identify them. One of the ways that dyes can be quickly identified is through the use of spectrophotometry, which is an area of science that deals with how specific materials absorb and reflect light.

Spectrophotometers work by exposing a sample material to a polychromatic light source. The reflected light from the sample is then split to its various components, within the visible spectrum. The result will be what is known as a reflectance or spectral curve. The resulting data can now easily be analyzed to give a quantifiable measure of the sample's color. This can be especially important in the food industry because foods have specific dyes that they are allowed to have in them, and any deviation can be the cause of a discarded batch of products, could turn consumers off to the product, or could induce fines from governmental agencies, under certain circumstances. The manufacturer is required to strictly adhere to the product label with regards to the ingredients, including food dyes, that make up the recipe for each food product. Thus, food producers tend to be very careful when analyzing food colors, and there are three primary methods for doing so:

Before production, food producers tend to collect resources and ingredients from many places before they produce the actual end product. These ingredients, raw materials, can be analyzed using spectrophotometers to ensure that no nonstandard ingredients reach the production line, and this cuts down on waste and saves time by making sure that only approved ingredients even make it to production.

During production, the food manufacturing process can sometimes involve many steps and it's possible that food colorings could become mixed or diluted at any stage of this process. Because of this, food producers often scan small test batches of products during the production process. This is done to ensure the quality of the end product and can identify any production-line level problems before they cause major issues down the line.

The manufacturer can also look into checking the color of the product as it is being produced. Color information can also be obtained, in real time, and can report to process control indicating whether the product color is within prescribed tolerances. If the color of the product does drift out of spec, the in-line system can send a signal to process control to affect a change in the color of the product.

After production is completed. There are many factors that can cause food dyes to change color. If they are exposed to oxygen or light for too long, or if they are accidentally mixed with other dyes, even small deviations in dye color can cause big changes in the color of end products. Because of this, food manufactures generally test a number of product samples before the finished product is shipped to retailers or distributors. This is done to ensure the quality of the product and to make sure that if any deviations have occurred, that they are caught early enough and meet quality and color specifications before they reach customers.

Regardless of the color being used, or the food that it's being used in, any federally approved dye will have a known quantifiable values. Because of this, food manufacturers are usually able to quickly find and identify color deviations before they can become a problem for retailers or consumers.

Color & Appearance Measurement Blogs

Light & Display Measurement Blogs