Canola oil is a type of vegetable oil derived from the seeds of the canola plant, which is a cultivar of rapeseed. It is known for its light flavor, high smoke point, and health benefits, including low levels of saturated fat and high levels of omega-3 fatty acids.²²  Canola oil is commonly used for cooking, frying, and as an ingredient in salad dressings and margarine. It is also used in some industrial applications, such as biodiesel production.

Chlorophyll is present in various vegetable oils, including olive and canola oil. In olive oil, chlorophyll and its derivatives contribute to the green color, with absorption peaks at 420 nm, 456 nm, 484 nm, and 670 nm primarily due to pheophytin derivatives.^17,19

In contrast, canola oil typically lacks a similar absorption spectrum, indicating chlorophyll removal during processing. The presence of chlorophyll in canola oil can lower its quality by hindering hydrogenation and promoting oxidation.^5–7 Chlorophyll removal processes exist for canola oil, but the remaining chlorophyll must be measured for quality control. The American Oil Chemists Society (AOCS) has a spectrophotometric method (Method Cc 13d – 55) for determining chlorophyll content in refined oils.

We analyzed samples of these oils using an UV-Visible spectrophotometer to see if the technique met standards and we are sharing the results.

About UV-Vis

UV-Vis spectroscopy is a technique used to measure how much ultraviolet (UV) and visible (Vis) light a substance absorbs.  In this method, a beam of UV or visible light is directed at a sample, which can be either a liquid or a solid. The light is either absorbed by or passes through the sample. By measuring the intensity of light which is able to pass through the sample and the light intensity without the sample present, the absorbance can be determined and is recorded as a function of wavelength. Different substances absorb light at different wavelengths, creating a unique absorption spectrum. By analyzing this spectrum, you can identify the substance and, through Beer’s law, determine its concentration in the sample.

UV-Visible absorption spectroscopy is a technique used to measure how much ultraviolet (UV) and visible (Vis) light a substance absorbs.  A beam of UV or visible light is directed at a sample. The light passes through the sample, which can be a liquid or a solid. On the other side of the sample, a detector measures the intensity of the light that has passed through. The amount of light absorbed by the sample at different wavelengths is recorded. Different substances absorb light at different wavelengths, creating a unique absorption spectrum. By analyzing this spectrum, you can identify the substance and determine its concentration in the sample.

Canola Oil Analysis Study and Results

A canola oil sample was measured using a 5 cm quartz cuvette to quantify remaining chlorophyll content. The spectrum showed no significant features in the red spectral region, indicating minimal chlorophyll presence. A modified version of AOCS method Cc 15d – 55, utilizing Beer’s law, was used to determine the extinction coefficient (e) for chlorophyll a (Chl a) in canola oil, which was found to be 0.11 ± 0.01 ppm⁻¹ cm⁻¹ at 666 nm. Using this coefficient, the chlorophyll content was calculated to be 0.01 ppm, indicating negligible chlorophyll presence. This low concentration is typical for commercially refined canola oils.

You can read more details about the oil samples in our application note, Analysis of chlorophyll content in food products through UV-Visible absorption measurements. It outlines in detail, the preparation, instrumentation, the absorptivity spectra, wavelength maxima tables, results, and references.

We concluded from those results that UV-Visible Absorption Spectroscopy provides valuable insights into product quality, processing methods, and development, helping to ensure that food products containing chlorophyll, including canola oils, meet the highest standards.

Additional Resources and References

• Application Note: Analysis of chlorophyll content in food products through UV-Visible absorption measurements
• Instrument Information: UV-Visible spectrophotometers
• 3D Tour of the instrument

References used above and in the application note:

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22. Colorado State University, Kendall Reagan Nutrition Center website, © 2025 College of Health and Human Sciences, https://www.chhs.colostate.edu/krnc/monthly-blog/cooking-with-fats-and-oils/