Sample interview questions: Can you explain your knowledge of the chemical reactions involved in food oxidation processes?
Sample answer:
Chemical Reactions Involved in Food Oxidation Processes
Food oxidation is a major cause of food spoilage, leading to changes in flavor, texture, and nutrient content. Understanding the chemical reactions involved in this process is crucial for developing effective preservation methods.
Lipid Oxidation: Rancidity
- Initiation: Free radicals (e.g., from heat or light) abstract a hydrogen atom from unsaturated fatty acids, forming a lipid radical.
- Propagation: Lipid radicals react with molecular oxygen to form lipid peroxy radicals, which continue the chain reaction.
- Termination: Lipid peroxy radicals react with each other or with antioxidants, ending the chain reaction.
Protein Oxidation:
- Initiation: Amino acid side chains (e.g., methionine) react with free radicals or reactive oxygen species (ROS) to form protein radicals.
- Propagation: Protein radicals can react with oxygen, other protein radicals, or antioxidants.
- Consequences: Protein oxidation can result in denaturation, loss of functionality, and protein aggregation.
Carbohydrate Oxidation:
- Maillard Reaction: Reducing sugars react with amino acids to form complex mixtures of compounds (e.g., melanoidins) that contribute to browning and flavor development.
- Caramelization: Sugars react with heat to produce characteristic brown colors and flavors.
- Oxidative Degradation: Carbohydrates can be oxidized by ROS, leading to the formation of aldehydes, ketones, and other compounds that contribute to off-flavors.
Antioxidant Systems in Foods