Two toxic non-volatile aldehydes, 4-hydroxy-2-hexenal (HHE) and 4-hydroxy-2-nonenal (HNE) as undesired by-products after thermal processing of vegetable oils high in unsaturated fatty acids raise health concerns.


It is a fact that vegetable oils with a high content of polyunsaturated omega-3 and omega-6 fatty acids (PUFA) contribute to a balanced and healthy diet. However, each of the double bonds in unsaturated fatty acids is sensitive to oxidation processes. Thermal treatment of vegetable oils increases the risk of undesirable formation of degradation products. It has been reported that HHE and HNE are formed under these conditions. Both degradation products are highly reactive towards biomolecules such as proteins, DNA and phospholipids and lead to structural changes.


Studies indicate that HHE and HNE are involved in the development and spread of known diseases, e.g. atherosclerosis, diabetes and cancer. Both highly toxic compounds have been identified in a number of commercially available edible oils in low but measurable concentrations. Formation is dependent on processing and increases with temperature and exposure time. During the deep-frying process these critical conditions can be easily reached. Any strategy to reduce the formation of these aldehydes should be based on a reliable analysis of the HHE and HNE contents in edible and deep-frying oils and also in the deep-fried products.




4-hydroxi-2-nonenal (HNE)                                                                        4-hydroxi-2-hexenal (HHE)

Our specialists at AGROLAB Dr. A. Verwey in Rotterdam have developed a GC MS/MS method for the determination of HHE and HNE in vegetable oils and look forward to supporting your efforts to minimize the risk with their analytical know-how.




Author: Dr. Frank Mörsberger