New research approach improves the flavor stability of flaxseed oil and extends its shelf life
Successful application on a laboratory scale: natural precursors of bitter-tasting compounds can be gently removed from the oil using bleaching earth
image:
The photo shows scientist Dr. Roman Lang in his office in front of his computer.
view moreCredit: photo: Dr. Gisela Olias / Leibniz-LSB@TUM
How can the mild flavor of flaxseed oil be preserved for longer? A research team led by Roman Lang from the Leibniz Institute for Food Systems Biology at the Technical University of Munich has investigated this question. As the team demonstrates in its latest study, natural precursors of bitter-tasting compounds can be gently removed from the oil using bleaching earth (magnesium-aluminum silicate). This results in significantly fewer bitter-tasting compounds formed during storage, and the flaxseed oil remains flavor-stable for longer. The particular advantage: The high content of health-beneficial fatty acids as well as the oil’s typical character are preserved despite the purification process.
The German Federal Center for Nutrition recommends reducing saturated fatty acids in the diet in favor of polyunsaturated fatty acids, as this can help lower LDL cholesterol levels and reduce the risk of coronary heart disease. Flaxseed oil can contribute to this, as it is particularly rich in the polyunsaturated omega-3 fatty acid alpha-linolenic acid.
However, flaxseed oil has a drawback: while it has a pleasantly mild taste when fresh, it quickly develops bitter notes during storage and eventually becomes inedible. Previous research by the Leibniz Institute and the Technical University of Munich had already shown that so-called cyclolinopeptides are responsible for this change in taste. These peptides, which are naturally present in the oil, oxidize during storage into substances with a strong bitter taste.
“We therefore investigated whether the flavor stability of flaxseed oil can be improved by specifically removing these cyclolinopeptides,” explains principal investigator Roman Lang. To test this hypothesis, the research team examined eight mineral-based cleaning agents approved for the refining of edible oils, including bleaching earth.
Successful application on a laboratory scale
On a laboratory scale, the research team at the Leibniz Institute has now succeeded in selectively reducing the natural bitter compound precursors using magnesium-aluminum silicate. When the researchers mixed 200 grams of oil with 10 grams of the natural mineral, stirred it for 20 minutes at 30°C, and separated the mineral again by centrifugation, the cyclolinopeptide content in the oil decreased by more than 80 percent. The color, odor, and fatty acid profile of the oil remained largely unchanged.
Sensory tests subsequently confirmed the success of the new research approach: While the untreated flaxseed oil exhibited a noticeable bitterness right from the start, the treated oil tasted hardly bitter at all. The taste advantage of the treated oil persisted even over a longer period.
As the research team further reports, although the bitterness increased in both samples after nine weeks of storage in the dark, the treated oil reached only the bitterness level of fresh, untreated oil. Even at room temperature, under UV light and air exposure, the oil purified with bleaching earth remained milder for longer and exhibited significantly lower concentrations of bitter-tasting oxidation products.
Potential for more sustainable food production
Given the rising demand for omega-3-rich foods, the new research approach offers a solid foundation for extending the sensory shelf life of flaxseed oil and increasing consumer acceptance—without chemical additives or complex refining.
The Researchers view the reduction of cyclolynopeptides as a sustainable approach to waste prevention due to the extended shelf life.
In further studies, they aim to investigate the optimal combination of materials used, as well as the influence of treatment duration and temperature on cyclolinopeptide residues and the stability of polyunsaturated fatty acids, in order to further refine the purification process.
Publication: Zavrak, S., Graßl, A., and Lang, R. (2026). Removal of cyclolinopeptides leads to reduced bitter taste of flaxseed oil. Appl Food Res. 10.1016/j.afres.2026.101777. https://doi.org/10.1016/j.afres.2026.101777
Funding: The research was funded by the Leibniz Institute for Food Systems Biology at the Technical University of Munich. No specific funding was received from institutions in the public, private, or non-profit sectors.
More Information:
Alpha-linolenic acid (ALA) is one of the omega-3 fatty acids that are essential for humans. This means that the body cannot produce it on its own but must obtain it through diet. The German Nutrition Society (DGE) recommends that adults consume about 1.1 grams of ALA daily, which is already contained in a single teaspoon of flaxseed oil. ALA serves as the precursor for the formation of the omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).
However, the body converts ALA into EPA and DHA only to a limited extent. Studies show that only about five to six percent of ingested ALA is converted to EPA, and less than one percent to DHA (J. T. Brenna, et al., 2009; Prostaglandins, Leukotrienes, and Essential Fatty Acids, doi:10.1016/j.plefa.2009.01.004). High levels of omega-6 fatty acids in the diet can further significantly reduce this conversion. Therefore, a balanced ratio of omega-6 to omega-3 fatty acids is considered important. The DGE recommends a ratio of about 5:1. Compared to other vegetable oils, flaxseed oil has particularly favorable values, with a ratio between 1:3 and 1:6.
One study suggests that an ALA-rich diet, combined with a diet relatively low in omega-6 fatty acids, can increase EPA levels in tissues to a degree similar to that achieved by fish oil supplementation (E. Mantzioris, et al. 1994; The American Journal of Clinical Nutrition. 59 (6): 1304–1309). The extent to which ALA also contributes to maintaining DHA levels is still a subject of scientific debate. However, one thing is clear: ALA plays a role in ensuring an adequate supply of omega-3 fatty acids, making flaxseed oil an important source of omega-3 fatty acids, particularly for people who eat little ocean fish.
Read also: Why Stored Flaxseed Oil Tastes Bitter—and What You Can Do About It
Publication: Lang, T., Frank, O., Lang, R., Hofmann, T., and Behrens, M. (2022). Activation Spectra of Human Bitter Taste Receptors Stimulated with Cyclolinopeptides Corresponding to Fresh and Aged Linseed Oil. J Agric Food Chem. 10.1021/acs.jafc.2c00976. pubs.acs.org/doi/abs/10.1021/acs.jafc.2c00976
Funding: This research was partially supported by the German Research Foundation (DFG) (BE 2091/7-1 to MB).
Did you know?
Linseed oil is also used for craft purposes. However, caution is advised, as rags or brushes soaked in linseed oil can also spontaneously combust (Michael Kundel: Fires Caused by Spontaneous Combustion, In: Schadenprisma / Fire Protection. 3/2013, p. 3, at schadenprisma.de, www.schadenprisma.de/pdf/sp_2013_3_1.pdf).
Information About the Institute:
The Leibniz Institute for Food Systems Biology at the Technical University of Munich (Leibniz-LSB@TUM) comprises a unique research profile at the interface of Food Chemistry & Biology, Chemosensors & Technology, and Bioinformatics & Machine Learning. As this profile has grown far beyond the previous core discipline of classical food chemistry, the Institute spearheads the development of a food systems biology. Its aim is to develop new approaches for the sustainable production of sufficient quantities of food whose biologically active effector molecule profiles are geared to health and nutritional needs, but also to the sensory preferences of consumers. To do so, the Institute explores the complex networks of sensorically relevant effector molecules along the entire food production chain with a focus on making their effects systemically understandable and predictable in the long term.
A Member of the Leibniz Associatation
The Leibniz-LSB@TUM is a member of the Leibniz Association, which connects 96 independent research institutions. Their orientation ranges from the natural sciences, engineering and environmental sciences through economics, spatial and social sciences to the humanities. Leibniz Institutes address issues of social, economic and ecological relevance.They conduct basic and applied research, including in the interdisciplinary Leibniz Research Alliances, maintain scientific infrastructure, and provide research-based services. The Leibniz Association identifies focus areas for knowledge transfer, particularly with the Leibniz research museums. It advises and informs policymakers, science, industry and the general public.
Leibniz institutions collaborate intensively with universities – including in the form of Leibniz ScienceCampi – as well as with industry and other partners at home and abroad. They are subject to a transparent, independent evaluation procedure. Because of their importance for the country as a whole, the Leibniz Association Institutes are funded jointly by Germany’s central and regional governments. The Leibniz Institutes employ around 21,300 people, including 12,200 researchers. The financial volume amounts to 2,2 billion euros.
Note on the use of AI
The press release was first translated from German into American English using DeepL Pro. The scientist an the communications team then reviewed the text for factual and linguistic accuracy, making corrections where necessary.
+++ Stay up to date via our LinkedIn channel +++
Journal
Applied Food Research
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Removal of cyclolinopeptides leads to reduced bitter taste of flaxseed oil
No comments:
Post a Comment