Monitoring aldehyde production during frying by reversed-phase liquid chromatography.

Area of Science:

• Food Chemistry
• Analytical Chemistry
• Toxicology

Background:

• Frying processes can generate aldehydes, such as acrolein, from triglyceride degradation.
• These aldehydes may be present in fried foods and their volatile emissions.
• Understanding aldehyde formation and distribution is crucial for food safety.

Purpose of the Study:

• To quantify low molecular weight aldehydes (LMWAs) in fried foods and their associated vapors.
• To investigate factors influencing LMWA formation during frying.
• To determine the distribution of LMWAs between the food matrix and steam distillate.

Main Methods:

• Liquid chromatography (LC) was used to monitor acrolein and other LMWAs in fried codfish and doughnuts.
• Vapors and steam distillate were trapped in a 2,4-dinitrophenylhydrazine solution.
• Hydrazones were extracted and analyzed using C18 reversed-phase LC, with confirmation by gas chromatography/mass spectrometry.

Main Results:

• No significant difference in LMWA content was observed in codfish fried at different temperatures (182°C vs. 204°C).
• Cake doughnuts exhibited higher acrolein levels compared to yeast-raised doughnuts.
• Frying medium freshness, duration, and batch size did not substantially affect LMWA production in doughnuts.
• The majority of formed LMWAs were found to codistill with steam.

Conclusions:

• Most low molecular weight aldehydes generated during frying volatilize with steam.
• Aldehyde content varies between different types of fried products (e.g., cake vs. yeast doughnuts).
• Temperature within the tested range does not significantly impact LMWA content in fried fish coatings.