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Oxidation of Cholesterol in Commercially Processed Cow's Milk
Mae Z Cleveland1, Natholyn D Harris1
1Department of Nutrition and Food Science, Florida State University, Tallahassee, Florida 32306.
Journal of Food Protection
|April 14, 2019
Summary
Cholesterol in most milk products remains stable during processing. However, instant nonfat dry milk contains oxidized cholesterol compounds, and stored milk lipids may form ketones.
Area of Science:
- Food Science
- Analytical Chemistry
- Dairy Science
Background:
- Oxidized cholesterol compounds are a concern in food products.
- Understanding cholesterol stability during milk processing is important for food safety and quality.
Purpose of the Study:
- To analyze various milk products for oxidized cholesterol compounds.
- To investigate the impact of heating and lipid storage on cholesterol in whole milk.
Main Methods:
- Analysis of pasteurized whole milk, UHT milk, evaporated milk, skim milk, and instant nonfat dry milk.
- Thin-layer chromatography (TLC) and Gas Chromatography-Mass Spectrometry (GC-MS) were employed.
- Examination of whole milk heating effects and lipid extract storage.
Main Results:
- Cholesterol remained stable in liquid milk forms (pasteurized, UHT, evaporated, skim) after processing.
- Instant nonfat dry milk was found to contain 7-hydroxy-cholesterol.
- Heating whole milk did not produce oxysterols, but storage of milk lipids yielded steroidal ketones.
Conclusions:
- Liquid milk cholesterol is generally stable under common processing conditions.
- Instant nonfat dry milk presents a potential source of oxidized cholesterol.
- Long-term storage of milk lipids may lead to the formation of undesirable steroidal ketones.