Influences on product discoloration of detergent products

Plastic detergent container on white background with clipping path
Plastic detergent container on white background with clipping path


The color of the end product is a key criterion that dictates consumer perception with regard to how the product will perform during application. In a recent study by Mohamed S. Manga et al. from the University of Leeds, UK the influence of numerous formulation and processing conditions on product discoloration where investigated.

Product should match aesthetics demand by consumers

Investigations into detergent powder discoloration have been limited and not well documented in the public domain. Therefore, there is a need to understand the influence of process parameters and raw material properties on the final product color. This knowledge could be used to ensure that the product matches the aesthetics demanded by consumers. In their study, Manga et al. investigated potential sources influencing product discoloration during the neutralization reaction within a laboratory-scale granulator using a spectrophotometer. The influence of drying temperature, particle size, raw material quality, and raw material processing are reported herein.

Raw material purity grade is crucial

In their article the researchers report on the influence of formulation and processing conditions on the optical properties of detergent powder formed in a high-shear mixer. Particle size plays an important role in determining how white the sample appears, especially if the sample undergoes segregation or if high shear rates are used during the granulation process. Another key finding is that the drying temperature can lead to discoloration of any unreacted organic compounds still present within the granules. The formulation itself also affects the perceived color of the final product. Improving the raw material purity grade and selecting the optimum vehicle to deliver key components such as optical brighteners can lead to powders that appear both light and blue (i.e., with high whiteness), which is important for consumer acceptance of the final product.

Spray application of optical brightener is better

The biggest improvement in color performance occurs with spray application of an optical brightener dispersion rather than pouring it in. Additional brightener spray applications after the granules are dry illustrates that increasing the brightener concentration at the granule surface produces larger improvements in product whiteness than embedding of the brightener within the granules.

The study entitled “The impact of raw material properties and process conditions on the color of a powdered formulated detergent product” has been published in Particuology, Vol. 45, August 2019, Pages 35-41

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