Quick Takeaway: Oxidation occurs when oxygen reacts with food molecules, causing browning, rancidity, and nutrient loss. Antioxidants and proper storage can slow this process.
What is Oxidation?
Oxidation is a chemical reaction where:
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Oxygen gains electrons from food molecules
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Food molecules lose electrons and become unstable
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Free radicals form that can damage other molecules
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Chain reactions occur that accelerate the process
Types of Food Oxidation
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Enzymatic browning: Polyphenol oxidase + oxygen (apples, potatoes)
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Lipid oxidation: Fats + oxygen (rancid oils, butter)
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Protein oxidation: Proteins + oxygen (meat discoloration)
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Vitamin oxidation: Vitamins + oxygen (nutrient loss)
Factors Affecting Oxidation
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Oxygen exposure: More oxygen = faster oxidation
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Temperature: Higher temps = faster reactions
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Light: UV light accelerates oxidation
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Metals: Iron and copper catalyze oxidation
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pH: Acidic conditions slow some oxidation
Preventing Oxidation
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Antioxidants: Vitamin C, E, polyphenols block free radicals
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Vacuum sealing: Removes oxygen from packaging
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Refrigeration: Slows chemical reactions
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Acid treatment: Lemon juice on cut fruits
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Blanching: Destroys enzymes that cause browning
Common Examples
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Cut apples: Turn brown due to enzymatic oxidation
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Rancid butter: Lipid oxidation creates off-flavors
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Stale nuts: Lipid oxidation makes them taste bitter
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Faded vegetables: Oxidation destroys pigments
Beneficial Oxidation
Some oxidation is desirable:
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Aging meat: Controlled oxidation develops flavor
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Wine aging: Oxidation creates complex flavors
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Cheese ripening: Oxidation develops characteristic tastes
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Tea processing: Oxidation creates different tea types
Storage Tips
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Refrigerate: Slows oxidation reactions
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Use airtight containers: Limits oxygen exposure
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Add antioxidants: Lemon juice, vitamin C
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Avoid light: Store in dark places
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Use quickly: Fresh foods have less oxidation
