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Oxidation of frying oils during intermittent usage
Nagao Totani1, Sayuri Tateishi, Terutoshi Mori
1Faculty of Nutrition, Kobe-Gakuin University, Kobe, Japan. totani@nutr.kobegakuin.ac.jp
Journal of Oleo Science
|November 10, 2012
Summary
Hospital frying oils show poor correlation between color and oxidation markers like polar compounds (PC), carbonyl values (CV), and acid values (AV). Oil standing time significantly contributes to oxidation, impacting food safety.
Area of Science:
- Food Science
- Analytical Chemistry
- Oxidation Chemistry
Background:
- Commercial frying oils show strong correlations between Gardner color and oxidation indicators (polar compounds, carbonyl value, acid value).
- This correlation is notably absent in frying oils used in hospital kitchens, suggesting unique degradation pathways.
Purpose of the Study:
- Investigate the reasons for the lack of correlation between frying oil color and oxidation markers in hospital settings.
- Determine the primary factors contributing to oil degradation in hospital deep-frying operations.
Main Methods:
- Collected and analyzed deep-fried oils from hospital kitchens, varying in patient numbers, fatty acid composition, and frying frequency.
- Assayed oils for polar compounds (PC), carbonyl values (CV), acid values (AV), and Gardner color.
- Monitored oxygen absorption in used oils upon standing at room temperature.
Main Results:
- Confirmed the absence of a strong correlation between oil color and PC, CV, or AV in hospital frying oils.
- Established the oxidation order for repeatedly used oils: soybean oil > blended oil > canola oil.
- Demonstrated that oil standing time at room temperature significantly increases oxygen absorption and oxidation.
Conclusions:
- Oil color is an unreliable indicator of oxidation in hospital frying oils.
- Both thermal treatment during frying and post-frying standing time contribute significantly to oil oxidation.
- Managing oil standing time is crucial for controlling oxidation and maintaining oil quality in hospital kitchens.
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