Overview
This lecture covers food spoilage and contamination, their causes, prevention methods, and the roles of different microorganisms, as well as safe food handling practices.
Causes and Types of Food Spoilage
- Food spoilage can be caused by physical damage, insects, rodents, chemical breakdown, and microorganisms.
- Physical damage occurs during transport or poor handling, allowing bacteria to enter.
- Rodents and insects can contaminate food, especially if left on the floor or in unsanitary delivery areas.
- Chemical breakdown leads to loss of food quality through changes in composition.
- Main types of spoilage include mold, rotting, sliminess, color change, and unwanted fermentation.
Bacterial Growth and Interactions
- Different strains of bacteria compete for resources; the fastest-growing strain dominates.
- Environmental conditions (temperature, moisture) affect which bacteria thrive.
- Waste from one microbe can inhibit another, causing waves of spoilage.
- Storage and treatment methods (e.g., pasteurization, vacuum packing) influence which microbes are present.
Sources and Prevention of Food Contamination
- Main sources of contamination: people, surfaces, and cross-contamination with other food.
- Poor food hygiene and unsanitized surfaces spread bacteria.
- Mixing raw or unwashed foods can contaminate others (e.g., tomato in a feta cheese container).
Handling Specific Food Groups
- Raw meat and poultry can contaminate cooked foods if not separated.
- Frozen meat and poultry still harbor bacteria, which multiply upon thawing.
- Proper thawing is required before cooking to ensure bacteria are killed; cooking from frozen is unsafe.
- Cooked meats can still cause illness if cooked at too low a temperature or not long enough.
- Fish is highly perishable and must be kept at proper cold temperatures.
- Dairy, even if pasteurized, spoils quickly if left open or improperly stored.
- Eggs can harbor salmonella; use only reputable sources for raw egg consumption.
- Dry goods are less risky but can be contaminated by pests or unsanitary storage conditions.
Key Terms & Definitions
- Food Spoilage — The process by which food deteriorates and becomes unsafe or unappealing to eat.
- Pasteurization — Heating food (e.g., milk) to kill harmful bacteria.
- Cross-contamination — Transfer of harmful microorganisms from one food or surface to another.
- Salmonella — A type of bacteria commonly found in poultry and eggs that causes food poisoning.
- Fermentation — Chemical breakdown of substances by bacteria, yeasts, or other microorganisms.
Action Items / Next Steps
- Complete individual research assignment questions.
- Watch the movie "Ratatouille" and answer the related questions.
- Begin group work and research for your presentation using multiple sources.
- Prepare a detailed PowerPoint presentation with your group.