Formation of 4‐Hydroxy‐2‐Trans‐Nonenal, a Toxic Aldehyde, in Thermally Treated Olive and Sunflower Oils

Abstract

4‐Hydroxy‐2‐trans‐nonenal (HNE) is a toxic aldehyde produced mostly in oils containing polyunsaturated fatty acid due to heat‐induced lipid peroxidation. The present study examined the effects of the heating time, the degree of unsaturation, and the antioxidant potential on the formation of HNE in two light olive oils (LOO) and two sunflower oils (one high oleic and one regular) at frying temperature. HNE concentrations in these oil samples heated for 0, 1, 3, and 5 hours at 185 °C were measured using high‐performance liquid chromatography. The fatty‐acid distribution and the antioxidant capacity of these four oils were also analyzed. The results showed that all oils had very low HNE concentrations (<0.5 μg g−1 oil) before heating. After 5 hours of heating at 185 °C, HNE concentrations were increased to 17.98, 25.00, 12.51, and 40.00 μg g−1 in the two LOO, high‐oleic sunflower oil (HOSO), and regular sunflower oil (RSO), respectively. Extending the heating time increased HNE formation in all oils tested. It is related to their fatty‐acid distributions and antioxidant capacities. RSO, which contained high levels of linoleic acid (59.60%), a precursor for HNE, was more susceptible to degradation and HNE formation than HOSO and LOO, which contained only 6–8% linoleic acid.

Rest Plant Materials with Natural Antioxidants Increase the Oxidative Stability of Omega-3-Rich Norwegian Cold Pressed Camelina sativa Oil

“…Results reported from unoxidized unsaturated vegetable oils vary from 0.01 to 0.2 μg/g of oil, which are in agreement with our results. Levels reported in oxidized oils vary from 2.0 to 45 μg/g of oil. − In one of the studies, oxidized rapeseed oil reached 4-HHE and 4-HNE levels of respectively 14 and 15 μg/g of oil after 11 days of storage of 28 g of oil in 1.1 L closed vessels in the dark at 37 °C, which are respectively about 5 and 15 times higher than our data. The other reported numbers (soybean, sunflower, palm, corn, linseed, camelina, and peanut oils) are much higher than in the present study, since these data are from studies of deep-frying of oils, which have been exposed to far higher temperatures (>180 °C).…”

“…Results reported from unoxidized unsaturated vegetable oils vary from 0.01 to 0.2 µg/g oil 40 , which are in agreement with our results. Levels reported in oxidized oils vary from 2.0 to 45 µg/g oil [40][41][42][43] . In one of the studies 40 , oxidized rapeseed oil reached HHE and HNE levels of respectively 14 µg/g and 15 µg/g oil after 11 days storage of 28 grams oil in 1.1 litre closed vessels in dark at 37 °C, which are respectively about 5 and 15 times higher than our data.…”

Impact of Heating Temperature and Fatty Acid Type on the Formation of Lipid Oxidation Products During Thermal Processing

“…Some recent reports showed that the total amount of GO, MGO, and 2,3-BD formed 55- and 15-fold in heated butter and margarine (from 100 to 200°C), and the volatiles were increased with the temperature and constant with time in olive oils ( 5 , 12 ). The content of 4-HNE was increased in the sunflower oil (185°C for 5 h) rich in linoleic acid (LA) and was more susceptible to decomposition ( 13 ). The close relationship between the UFAs and their corresponding volatile aldehydes was also revealed by some studies ( 14 , 15 ).…”

4-Hydroxynonenal (HNE), a Toxic Aldehyde in Fried Chicken from Fast Food Restaurants and a Grocery Store

“…A number of previous experiments by the author have shown the formation of HNE due to heat treatments in various oils [34]- [39]. HNE has also been shown to incorporate into fried food [40] [41].…”