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Questions and Answers
What role do coliform bacteria play as an indicator species in assessing fecal contamination?
What role do coliform bacteria play as an indicator species in assessing fecal contamination?
Coliform bacteria indicate fecal contamination as they are commonly found in the intestines of humans and animals but do not typically grow in nature without such contamination.
Explain how pasteurization impacts the microbial load in food products like milk.
Explain how pasteurization impacts the microbial load in food products like milk.
Pasteurization reduces microbial loads in foods by heating them to a temperature that kills harmful bacteria without significantly affecting the food's quality.
Describe the significance of storing milk at 4 degrees Celsius.
Describe the significance of storing milk at 4 degrees Celsius.
Storing milk at 4 degrees Celsius is critical as it slows bacterial growth, thereby preventing the spoilage and potential health risks associated with pathogenic bacteria.
Identify the most common foodborne infection linked to poultry and its causative agent.
Identify the most common foodborne infection linked to poultry and its causative agent.
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How can fruits and vegetables become contaminated before reaching consumers?
How can fruits and vegetables become contaminated before reaching consumers?
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What is the main process involved in the Standard Plate Count method for determining bacterial load?
What is the main process involved in the Standard Plate Count method for determining bacterial load?
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Explain how serial dilution aids in estimating bacterial concentrations in food products.
Explain how serial dilution aids in estimating bacterial concentrations in food products.
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Why might the Standard Plate Count method be considered inaccurate?
Why might the Standard Plate Count method be considered inaccurate?
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What is the effect of Ultra High Temperature (UHT) pasteurization on food products?
What is the effect of Ultra High Temperature (UHT) pasteurization on food products?
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How do contamination routes in the food supply chain vary among different food types?
How do contamination routes in the food supply chain vary among different food types?
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Study Notes
Coliform Bacteria
- Gram-negative bacteria
- Do not form spores
- Ferment lactose, producing acid and gas
- Fecal coliforms are found in high concentrations in human and animal intestines
- Indicator species; rarely found in nature without fecal contamination (e.g., E. coli)
Milk
- Pasteurization reduces microbial loads in milk and fruit juices to acceptable levels
- Ultra-High Temperature (UHT) pasteurization sterilizes food if done aseptically
- Store milk at 4 degrees Celsius to prevent bacterial growth
Chicken
- Salmonella is a common foodborne illness linked to contaminated poultry
Fruits and Vegetables
- Contamination can occur from soil or water during growth
- Processing, storage, and preparation can also introduce contamination
Determining Bacterial Levels in Food
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Standard Plate Count
- Serial dilutions of the food are plated on growth media
- Bacterial colonies (CFU) are counted
- CFU (colony-forming units) – one colony may result from multiple bacteria
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Serial Dilution
- Creates very dilute solutions without precise measurements for small liquid quantities
- A series of dilutions are performed (e.g., diluting a solution, then diluting the dilution, etc.)
- If a 0.1 sample is plated, multiply CFU by 10 to calculate CFU/ml.
- If a 0.05 sample is plated, multiply CFU by 20 to calculate CFU/ml.
- Average results from multiple dilutions to determine final bacteria count/ml.
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Description
This quiz covers the key concepts related to microbial safety in food, including the characteristics of coliform bacteria, the importance of pasteurization for milk, and contamination risks in fruits and vegetables. Additionally, it discusses methods for determining bacterial levels in food to ensure safety.