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Questions and Answers
What is the primary purpose of food preservation?
What is the primary purpose of food preservation?
Which method focuses on keeping microorganisms from contaminating food?
Which method focuses on keeping microorganisms from contaminating food?
Which of the following methods decreases microbial growth by creating unfavorable conditions?
Which of the following methods decreases microbial growth by creating unfavorable conditions?
What is a common outcome of food spoilage?
What is a common outcome of food spoilage?
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How does drying preserve food?
How does drying preserve food?
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What type of preservation method would involve heat treatment to inactivate food enzymes?
What type of preservation method would involve heat treatment to inactivate food enzymes?
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Which of the following is NOT a method for food preservation?
Which of the following is NOT a method for food preservation?
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Which factor is essential for minimizing the risk of spoilage in food preservation?
Which factor is essential for minimizing the risk of spoilage in food preservation?
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What is the main effect of low temperatures on the metabolic activity of food-borne microorganisms?
What is the main effect of low temperatures on the metabolic activity of food-borne microorganisms?
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Which of the following genera contains psychrotrophic bacteria that are significant in food preservation?
Which of the following genera contains psychrotrophic bacteria that are significant in food preservation?
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What characterizes chilling or refrigeration storage?
What characterizes chilling or refrigeration storage?
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What is the primary factor that influences microbial load in food?
What is the primary factor that influences microbial load in food?
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Which method of freezing allows for the quickest temperature drop?
Which method of freezing allows for the quickest temperature drop?
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Which method is most effective for completely removing microorganisms from liquids?
Which method is most effective for completely removing microorganisms from liquids?
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How does temperature affect enzyme activity in biological systems?
How does temperature affect enzyme activity in biological systems?
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Which temperature range is commonly associated with common or cellar storage?
Which temperature range is commonly associated with common or cellar storage?
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What must be avoided when washing raw foods to ensure effective reduction of microbial load?
What must be avoided when washing raw foods to ensure effective reduction of microbial load?
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What is the primary purpose of using low temperatures in food preservation?
What is the primary purpose of using low temperatures in food preservation?
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What condition must be met for anaerobic preservation methods to be successful?
What condition must be met for anaerobic preservation methods to be successful?
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Which of the following best describes Controlled Atmosphere Packaging (CAP)?
Which of the following best describes Controlled Atmosphere Packaging (CAP)?
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What distinguishes slow freezing from fast freezing?
What distinguishes slow freezing from fast freezing?
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Which microorganism is particularly problematic in sous-vide processing?
Which microorganism is particularly problematic in sous-vide processing?
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What is a common consequence of suboptimal training of the workforce in food processing?
What is a common consequence of suboptimal training of the workforce in food processing?
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Which method does NOT contribute to food preservation?
Which method does NOT contribute to food preservation?
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Study Notes
Food Preservation Methods
- Food preservation prevents or delays changes in food, making it inedible or undesirable.
- Crucial due to:
- Seasonal food production
- Distance between food source and consumption
- Spoilage-related economic losses
- Microbial contamination leading to illness
Methods of Food Preservation
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General Principles:
- Prevention/delay of microbial growth
- Prevention/delay of self-decomposition
- Prevention of mechanical damage
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Microbial Control:
- Asepsis: Keeping microorganisms out (e.g., filtration)
- Removal of microorganisms (e.g., filtration)
- Inhibiting microbial growth (Low temp, drying, anaerobic environment)
- Killing microorganisms (heat or radiation)
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Prevention of Self-Decomposition:
- Deactivating food enzymes (e.g., heat treatments)
- Preventing chemical reactions (e.g., adding antioxidants to prevent oxidation)
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Prevention of Damage:
- Appropriate packaging, stacking, and storage
- Preservatives must not change the food's original nature
Achieving Preservation Goals
- Minimizing initial microbial load
- Creating unfavorable environment for growth
- Preventing physical damage
Specific Methods
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Asepsis (includes filtration): Prevents introduction of microorganisms, natural barriers, quality of raw materials, harvest/storage/transport conditions, processing plant conditions, aseptic approach, cleaning/sanitization, workforce training/awareness/buy-in, industrial packaging
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Filtration/Removal of Microorganisms: Limited to clear liquids (juices, beer, soft drinks, water, wine). Effective when combined with other methods. Washing raw foods, sanitation, trimming spoiled parts also important.
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Anaerobic or Gas Storage: Evacuating air and replacing with CO₂ or inert gas (nitrogen) within containers. Spores of some microorganisms may be resistant to heat but not anaerobic conditions.
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Vacuum Packaging: Removes all air. Modified Atmosphere Packaging (MAP): Gas atmosphere changes due to microbial activity and diffusion across packaging membrane (CO2, gas exchange). Controlled Atmosphere Packaging (CAP): Constant product environment throughout storage.
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Sous-Vide Processing: Packaging under vacuum in a barrier bag or container. Cooked in a high-moisture environment at a temperature sufficient for cooking/pasteurizing, not sterilizing. Important: some spores may survive this, e.g., Clostridium botulinum type E; heat-stable toxins (e.g., Staphylococcus aureus) are potential concerns. Improves nutritional quality and palatability.
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Use of Low Temperatures:
- Reducing microbial metabolic activity
- Stopping activity below freezing temperatures
- Enzyme activity depends on temperature; a rise in temperature correlates with faster enzyme reaction rates. Temperature coefficient (Q10): for every 10°C increase, a 1.5-2.5 fold increase in enzymatic reaction rate, between 0 - 40 degrees celsius Q10 is 2.
- Psychrotrophic (cold-loving) bacteria aren't affected as greatly by cold
- Storage types include common/cellar (10-15°C), chilling/refrigeration (just above freezing), freezing (-18°C or below).
- Microbial effectiveness of freezing depends on the microorganism, its physiological state, storage temperature, and duration, whether freezing is fast or slow, plus food composition factors (water content, high sugar/salt, acidity/low pH). Food should be sorted, washed, blanched or packaged before freezing to minimize microbial load.
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Description
Test your knowledge on various methods of food preservation and their principles. This quiz covers microbial control, prevention of self-decomposition, and damage prevention techniques. Understand the importance of preserving food to prevent spoilage and ensure safety.
