How to measure the colour of flour

How to measure the colour of flour

Measuring the colour of flour

There are many different types of flour available on the market both for public consumption and manufacturing purposes. Whether or not one acquires flour to sell in a supermarket or to use in the production of other food items such as cakes, biscuits or bread, to name just a few, the quality of the flour itself should be as good as it can possibly be.

Each type of flour produced has its own stereotypical appearance and colour associated; for example self-raising flour is white in colour whereas corn flour can have more of a yellow tinge and wholemeal flour appears browner. Whatever the type of flour, appearance quality should still be an important aspect during production.

What problems can be found in flour?

Any number of discolouration can occur during production due to a number of reasons such as mechanical error in a production machine or contaminant in any of the vitamins or other additives included in the flour’s production, not to mention the flour itself. Producing such a clean and white substance such as flour means that any deviations in appearance, however slight, will be noticed and may result in the flour being discarded.

For any white flour such as self-raising or plain, any yellowness detected with the end product can be undesirable and indicate an issue somewhere along the production line. Similarly for products such as corn flour or wholemeal flour, any whiteness found can be the result of an additive or contaminant.

How can quality be measured?

The use of a spectrophotometer in an application such as this is crucial in analysing the flour and providing quantifiable data that can tell the manufacturer what, if any, issues have occurred. A good method plus a reliable instrument can save time and money. Some good points to think of are as follows:

Create a good standard

In a plant that produces different types of flour it is helpful to have standards set. These standards are comprised of data taken from a perfected batch of flour that all samples should be compared to. Any spectrophotometer used should be able to store as many standards as the manufacturer has batches of flour and more. Depending on how thorough the analysis needs to be, there is always the option of setting standards for different types of flour at different stages during production. For example, one could set a standard for before and after vitamins etc. have been added for any number of flour types.

Sample preparation

Being in a factory environment with a vast amount of flour being produced daily requires a quick and simple method for any operative to follow that does not take up too much time in their routine. Obtaining a sample cup or petri dish that can hold a thick layer of the flour would result in an opaque sample that could be measured easily. The sample needn’t be compressed but it would be important to make sure the flour presented a smooth surface at the bottom of the sample cup for allow for more accurate data.

How to get the flour into the container for measurement is down to individual manufacturer protocol and how accurate the operator is! Pouring the sample into the cup is equally as good as spooning it in, although probably slightly more messy. It is not recommended to use the sample cup as a scoop as this can cover the outside with flour which can end up in the instrument and cause irregular results.


It must be understood that working with any powder substance can be messy and dust can settle anywhere. Therefore it is imperative that any instrument used be kept clean so not to interfere with measurements and any sample cups be thoroughly cleaned and dried between uses.


As stated, a spectrophotometer would be ideal as it would be able to give measurable data of the reflected colour of the product. When a consumer views the product, they are going to be looking at the reflected colour so having an instrument such as a spectrophotometer that can measure colour the way the human eye sees it is an irrefutably good choice.

If using receptacles such as sample cups, it is easier to have an instrument that can accommodate the cup sitting on top for measurements. If an instrument requires the sample to be placed inside or involves too much handling, there is a greater risk of contaminating the product and also the instrument which can affect the data given. An example? Any spectrophotometer chosen should have the abilities detailed earlier, such as the capacity for storing many standards and the layout to allow samples to be placed on top but it should also be sturdy, compact and self-contained if desired. This would mean that the instrument can be used on its own to decrease bench space used but can also be used in conjunction with software for an extra degree of analysis.

Whatever a manufacturer’s process in producing flour, keeping an eye on the appearance quality during the entire process can prevent whole batches from being discarded due to not meeting certain standards.

What would we use?

The ColorFlex EZ Spectrophotometer with a whiteness and yellowness index to use in conjunction with the CIE L*, a*, b* colour scale and EasyMatch QC software to allow for more detailed analysis.

Content Written by Rachael Stothard

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How to measure the colour of flour

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