Lipoxygenase activity assay

Lipoxygenase (LOX) is a key enzyme involved in the oxidation of polyunsaturated fatty acids, particularly linoleic and linolenic acids. This enzymatic reaction leads to the formation of hydroperoxides, precursors of volatile compounds responsible for aroma, but also for rancidity and loss of nutritional quality.

Measuring lipoxygenase activity therefore allows us to:

• Evaluate the oxidative stability of vegetable oils;
• Checking the freshness of seeds, legumes or enzyme extracts;
• Characterize functional ingredients rich in natural enzymes;
• Identify enzymatic sources for nutraceutical or cosmetic formulation.

This analysis is particularly useful in plant-based sectors that are sensitive to oxidation, such as products based on soy, wheat, peanuts or sunflowers.

Method of analysis

The analysis of lipoxygenase activity relies on spectrophotometric techniques, allowing real-time monitoring of the appearance of oxidation products:

• Reading at 234 nm: this wavelength allows quantification of the hydroperoxides formed during the enzymatic reaction, a direct signature of LOX activity.
• Titrimetry or enzyme kinetics: depending on the matrices and the needs, the method can be coupled with time monitoring for more precise quantification.

The results are generally expressed in enzyme units (U/g or U/mL) or in absorbance change per minute.

Affected matrices

Lipoxygenase activity assays are applicable to numerous food and plant matrices, including:

• Vegetable oils (soybean, sunflower, rapeseed, etc.) – control of oxidation and freshness;
• Seeds and flours – monitoring of viability, heat treatment or storage;
• Plant enzymatic extracts – standardisation of products with a functional purpose;
• Processed or nutraceutical products – quality control and labelling validation.

Industrial and regulatory interest

In the food industry, lipoxygenase plays an ambivalent role:

• Positive: under certain conditions, it contributes to the development of characteristic aromas (e.g., bread, green tea, beer);
• Negative: it accelerates oxidative rancidity, reduces nutritional value (loss of vitamins, destruction of essential fatty acids) and alters the color or smell of finished products.

Its dosage is therefore a very useful quality indicator, particularly in products rich in lipids or intended for long-term storage.

Recommended Related Analyses

For a complete understanding of oxidation phenomena or enzymatic activity, the following analyses can be performed in addition:

• Free acidity assay – an indicator of rancidity in oils and fats;
• Peroxide assay – measurement of primary lipid oxidation;
• Assay of linoleic acid – preferred substrate of lipoxygenase;
• Measurement of antioxidant activity (DPPH, ORAC, ABTS) – to assess the capacity to protect against oxidation.

YesWeLab: your partner for enzyme testing

At YesWeLab, we offer a complete solution for managing your enzymatic analyses. Thanks to a network of accredited partner laboratories (ISO 17025, COFRAC, etc.), we guarantee the quality, reliability, and traceability of every analysis.

Our digital platform allows you to:

• Manage your analysis requests easily;
• Track your samples in real time;
• Access your reports and results as soon as they are validated.

Need a lipoxygenase test?

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