Using the Gardner Scale to Enhance Quality and Create Colour Consistency in Edible Oils

In edible oil production, the colour of the product says a lot about its processing, storage, and overall quality. Olive oil is a prime example. Some olive oils are deep gold while others are pale yellow or dark brown. These colours vary widely based on the type of olive that manufacturers use as well as how the product is handled and stored before it's added to the shelves.

Edible oil manufacturers can apply the Gardner scale to create the colour consistency they need in their products.

The Gardner scale can be used to give you greater insight into your edible oil products. Image Source: Pexels user Pixabay

What Is the Gardner Colour Scale?

The Gardner colour scale is a method for identifying and categorizing the colour of transparent liquids. This scale only applies in the yellow to brown range, making it an excellent categorization method for fatty acids, resins, and edible oils. Manufacturers can rely on the manufacturing scales for a variety of edible oils such as canola, vegetable, peanut, and sunflower.

The original Gardner scale was developed in the 1920s and relies on liquid colours mixed inside clear glass tubes. Pioneers of this scale used materials like potassium chloroplatinate and potassium dichromate to make varying shades of yellow to brown. Since its inception, the Gardner colour scale has been updated to remove the bias that comes with human perception of colour.

How to Apply the Gardner Colour Scale to Edible Oils

To enhance the quality of the Gardner scale, the yellow-to-brown spectrum has been standardized with the help of spectrophotometers. This equipment applies quantitative values to colour by measuring the light that a sample absorbs and transmits.

If an edible oil product falls within the colour range in the Gardner scale, manufacturers can use spectrophotometers to measure the colour values and compare them to the colour standards on the scale. Advanced equipment can compare your sample measurement with a level in the Gardner scale and alert you when the colours do not match.

This colour comparison process is essential for colour consistency in edible oils. The Gardner scale is only one comparison scale you can apply to a range of colored products. For instance, the APHA scale offers many products that are mostly colorless. Refined soybean oil is an edible oil that falls into this colour range, and the APHA scale can help you identify colour variations in the product.

When comparing colours for your product, you may not want to commit to one scale or another right away. At HunterLab, our EasyMatch QC software can capture data from both colour scales simultaneously. This flexibility is ideal at different stages of the production process — especially with edible oils. Many oils start off in the yellow-to-brown Gardner scale when they're raw and become almost clear after processing. With the help of HunterLab, maintaining colour consistency is within reach.

How the Gardner Scale Helps Edible Oil Manufacturers Enhance Quality and Create Colour Consistency

Using a spectrophotometer with Gardner scale capabilities provides a number of benefits that can help you create higher-quality, more consistent edible oil products:

Raw Material Selection

During the selection process for your raw materials, the Gardner colour scale may help you identify materials that are most likely to produce the final colour you desire. For example, if you want to manufacture extra virgin olive oil that is as dark yellow as possible without adding artificial coloring to your final product, then you may choose to test the raw oil produced by a number of different olive species first. This testing process will help you identify the olive variety that consistently produces your ideal oil colour on the Gardner scale.

Refined Manufacturing

Another use for the Gardner scale among edible oil manufacturers is to ensure colour consistency from batch to batch. Various steps in the manufacturing process can impact the final colour of the oil product, which may impact both the real and perceived quality of the oil. When making olive oil, for example, manufacturers press the olives in order to extract liquid fat from the fruit. If the olives are exposed to too much oxygen during this process, the oil may oxidize and change colour, resulting in a lower-quality product. Similarly, the process of bleaching or refining the oil may cause it to appear lighter in colour compared to an oil that has not been through this process. By testing your edible oil for colour consistency throughout the manufacturing process, you can ensure that your products are being processed exactly as intended, as discoloration could be a sign of an inconsistency in the pressing or bleaching process.

Safer Storage

Finally, the Gardner colour scale can help you identify improper storage conditions. Edible oil products are highly sensitive to changes in temperature, lighting, and air quality. For instance, food-grade oil that has been stored in temperatures above 18 degrees Celcius (65 degrees Fahrenheit) is prone to heat damage, which may cause it to lighten significantly in colour. Likewise, oils exposed to too much oxygen as a result of an improper container seal and oils that are exposed to bright lights or natural sunlight are also likely to undergo undesirable colour changes before they reach your customers. Using a spectrophotometer that is capable of measuring edible oil against the Gardner colour scale, you can ensure that your products are being stored properly before they are shipped to your customers or distributors. Additionally testing a sample of your oil while it’s in storage may help you identify storage problems before they negatively impact your future products.

Facilitate Accurate Edible Oils Colour Measurement With Solutions From HunterLab

HunterLab carries spectrophotometers that excel in measuring the colour of edible oils. With embedded EasyMatch QC software and a smart user interface, manufacturer teams can maintain colour consistency across every edible oil product. Get in touch with us today to learn more about our equipment options.