Frying food in oil at high heat for an hour creates toxic chemicals in the oil, especially in sesame oil, even after just 10 minutes.
Scientific Claim
Deep-frying rapeseed, sunflower, sesame, and peanut oils at 190°C for 60 minutes with intermittent frying of chicken nuggets generates significant levels of toxic α,β-unsaturated aldehydes, including 4-hydroperoxy-(E)-2-alkenals, 4-hydroxy-(E)-2-alkenals, and 4,5-epoxy-(E)-2-alkenals, with sesame oil showing the highest accumulation.
Original Statement
“Even 10 min of deep-frying at this high temperature resulted in the formation of new aldehyde compounds... The sesame oil exhibited the highest quantities of (E)-2-alkenals, (E,E)-2,4-alkadienals, 4,5-epoxy-(E)-2-alkenals, combined 4-hydroxy/4-hydroperoxy-(E)-2-alkenals...”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
definitive
Can make definitive causal claims
Assessment Explanation
The study directly observes and quantifies aldehyde formation via high-field NMR under controlled frying conditions. The chemical identity and increase over time are definitive analytical results.
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.
In Vitro Chemical AnalysisLevel 4In EvidenceThe exact chemical profile and kinetics of aldehyde formation during frying under standardized conditions.
The exact chemical profile and kinetics of aldehyde formation during frying under standardized conditions.
What This Would Prove
The exact chemical profile and kinetics of aldehyde formation during frying under standardized conditions.
Ideal Study Design
One liter of each oil (n=4) heated to 190±2°C in a commercial fryer with intermittent frying of standardized chicken nuggets (50g every 5 min) for 0, 10, 30, 60, and 120 min; NMR and GC-MS quantification of 12 specific aldehydes in triplicate samples per time point.
Limitation: Does not measure human exposure or absorption.
Animal Toxicity StudyLevel 5Whether consuming fried oils causes tissue damage or genotoxicity in vivo.
Whether consuming fried oils causes tissue damage or genotoxicity in vivo.
What This Would Prove
Whether consuming fried oils causes tissue damage or genotoxicity in vivo.
Ideal Study Design
Mice (n=60) fed diets with 15% oil from either fresh or 60-min fried sesame oil for 12 weeks, with comet assay for DNA damage, liver 4-HNE adducts, and histopathology as primary endpoints.
Limitation: Cannot confirm human relevance of dose or metabolic response.
Evidence from Studies
Supporting (1)
The scientists heated the same oils in the same way as the claim says, and found that yes, harmful chemicals formed — especially in sesame oil — just like the claim said.