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What is one method of preventing microbial contamination in food preservation?
What is one method of preventing microbial contamination in food preservation?
Which of the following helps delay self-decomposition of food?
Which of the following helps delay self-decomposition of food?
What is the main goal of extending the lag phase in food preservation?
What is the main goal of extending the lag phase in food preservation?
How can the initiation of microbial growth in food be delayed?
How can the initiation of microbial growth in food be delayed?
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What process is used to destroy or inactivate food enzymes for preservation?
What process is used to destroy or inactivate food enzymes for preservation?
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What is a potential downside to using high heat in food preservation?
What is a potential downside to using high heat in food preservation?
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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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What effect does sublethal heat treatment have on microorganisms?
What effect does sublethal heat treatment have on microorganisms?
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What is the primary temperature and time used in the HTST method of pasteurization?
What is the primary temperature and time used in the HTST method of pasteurization?
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Which method employs a low temperature for an extended period?
Which method employs a low temperature for an extended period?
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What does the phosphatase test indicate about milk?
What does the phosphatase test indicate about milk?
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At what temperature does boiling typically occur to preserve low and medium acid foods?
At what temperature does boiling typically occur to preserve low and medium acid foods?
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What is the minimum temperature required for sterilization using steam?
What is the minimum temperature required for sterilization using steam?
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What is the purpose of detecting Clostridium botulinum in food sterilization?
What is the purpose of detecting Clostridium botulinum in food sterilization?
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Which of the following is NOT a method of preserving food mentioned?
Which of the following is NOT a method of preserving food mentioned?
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Which method allows heating milk to temperatures up to 150°C?
Which method allows heating milk to temperatures up to 150°C?
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What is the main objective of heat treatment in food preservation?
What is the main objective of heat treatment in food preservation?
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Which factor decreases the time required to kill microbial cells or spores?
Which factor decreases the time required to kill microbial cells or spores?
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What type of heating is defined as pasteurization?
What type of heating is defined as pasteurization?
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Which of the following is NOT a consequence of heat treatment on microbial cells?
Which of the following is NOT a consequence of heat treatment on microbial cells?
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During which phase do bacterial cells show the greatest resistance to heat?
During which phase do bacterial cells show the greatest resistance to heat?
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What is an example of a preservative method to supplement pasteurization?
What is an example of a preservative method to supplement pasteurization?
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Which type of heating involves temperatures above 100°C?
Which type of heating involves temperatures above 100°C?
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What can help to kill unwanted microorganisms during fermentation?
What can help to kill unwanted microorganisms during fermentation?
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What does thermal death time (TDT) specifically refer to?
What does thermal death time (TDT) specifically refer to?
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What is the thermal death point (TDP)?
What is the thermal death point (TDP)?
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What does the D Value represent?
What does the D Value represent?
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What effect do low temperatures have on microorganisms in food?
What effect do low temperatures have on microorganisms in food?
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At what minimum temperature does Clostridium botulinum type E begin to grow?
At what minimum temperature does Clostridium botulinum type E begin to grow?
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What is the typical temperature range for chilling or cold storage?
What is the typical temperature range for chilling or cold storage?
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What happens when there are changes in humidity during food storage?
What happens when there are changes in humidity during food storage?
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How does common or cellar storage generally affect fruits and vegetables?
How does common or cellar storage generally affect fruits and vegetables?
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What are the characteristics of small ice crystals formed during quick freezing?
What are the characteristics of small ice crystals formed during quick freezing?
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Which of the following is an advantage of quick freezing over slow freezing?
Which of the following is an advantage of quick freezing over slow freezing?
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What happens to bacteria during freezing?
What happens to bacteria during freezing?
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What effect does low temperature have on fatty acids in lipids?
What effect does low temperature have on fatty acids in lipids?
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What determines the rate of deterioration in foods before freezing?
What determines the rate of deterioration in foods before freezing?
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What occurs during the thawing process after quick freezing?
What occurs during the thawing process after quick freezing?
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Which statement is true about endospores during freezing?
Which statement is true about endospores during freezing?
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Which of the following does not happen during slow freezing?
Which of the following does not happen during slow freezing?
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What is one benefit of controlling air velocities in a storage room?
What is one benefit of controlling air velocities in a storage room?
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Which gas is best for storing eggs in controlled atmospheres?
Which gas is best for storing eggs in controlled atmospheres?
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What role does U.V. irradiation play in food storage?
What role does U.V. irradiation play in food storage?
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What is a primary benefit of freezing foods?
What is a primary benefit of freezing foods?
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Which of the following is an advantage of scalding or blanching vegetables?
Which of the following is an advantage of scalding or blanching vegetables?
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What is combined with gas storage to enhance preservation?
What is combined with gas storage to enhance preservation?
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What is a requirement for fruits and vegetables before freezing?
What is a requirement for fruits and vegetables before freezing?
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Which food item is best stored using 100% CO2?
Which food item is best stored using 100% CO2?
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Study Notes
Food Preservation
- Food preservation is a set of methods used to stop or slow spoilage of food to prevent it from deteriorating.
- Principles of food preservation include:
- Prevention or delay of microbial contamination
- Prevention or delay of self-decomposition of the food
- Prevention of damage by insects, animals etc.
- Application of food preservation:
- Introduce few spoilage organisms to lengthen lag phase. Reduce contamination.
- Avoid addition of actively growing microorganisms from logarithmic phase on unclean containers, equipment or utensils. Increase the lag phase.
- Unfavorable environmental conditions like : poor food quality, moisture, temperature, pH, oxidation potential or presence of inhibitors delay growth initiation.
- Damage to organisms during processing methods such as heating or irradiation to delay growth.
- Methods of Food Preservation:
- High Temperatures: Heat kills microbes by accumulating or clotting proteins or by coagulation or denaturation of proteins, blocking enzyme activity, metabolism and reproduction by destroying the outer cell wall.
- The factors influencing thermal resistance are time, initial concentration and previous history of vegetative cells or spores.
- The phases of growth or age also affect thermal resistance.
- Heat treatments include:
- Heating below 100°C (Pasteurization)
- Heating at about 100°C (Boiling)
- Heating above 100°C (Sterilization).
- Pasteurization:
- A heat treatment that kills some microorganisms(pathogens), not all.
- Temperature below 100°C
- Use steam, hot water, dry heat, or electric current to heat.
- Cool immediately after heating.
- Used when rigorous heat harm product quality.
- To kill pathogens in milk.
- To control spoilage organisms like yeasts in fruit juices.
- To kill competing microorganisms to allow for desired fermentation.
- Preservative methods to supplement pasteurization include refrigeration, keeping out microorganisms (packaging), addition of high sugar concentrations (e.g., sweetened condensed milk), and presence or addition of chemical preservatives (e.g., organic acids on pickles).
- Methods of Pasteurization:
- HTST (High-temperature short time): 71.7°C for 15 seconds.
- LTLT (Low-temperature long time): 62.8°C for 30 minutes.
- Ultra pasteurization: 137.8°C for 2 seconds.
- Boiling: Enough to kill everything but bacterial spores. Used for low and medium acid foods.
- Sterilization: Temperatures above 100°C using steam under pressure in pressure sterilizers or retorts to improve storage.
- Thermal Destruction of Microorganisms:
- Thermal death time (TDT): the time needed to kill a given number of microorganisms at a set temperature.
- Thermal death point (TDP): the temperature necessary to kill a given number of microorganisms in a fixed time (10 minutes).
- D value: the decimal reduction time; time to kill 90% of microorganisms.
- Low Temperatures:
- Used to slow chemical reactions, food enzyme action and microbial growth.
- Freezing prevents the growth of most food-borne microorganisms and refrigeration slows growth rates.
- Clostridium botulinum type E has a minimum growth temperature of 3.3°C.
- Yersinia enterocolitica grows at 0-3°C.
- Temperatures in low temperature storage include:
- Common or cellar storage: Below 15°C.
- Chilling or cold storage: -1 to 8°C.
- Freezing or frozen storage: Below -20°C.
- Use of gas storage with or without chilling.
- Thawing: bring frozen foods to room temperature before cooking or consuming
- Effect of freezing on microorganisms
-
Cocci is more resistant to freeze than Gram-negative rods.
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Certain foodborne pathogens like salmonella are less resistant than Staphylococcus aureus or vegetative cells of Clostridium sp.
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Unsaturated fatty acid increase at low temperatures, leading to better resistance to low temperature
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Description
Test your knowledge on the various methods of food preservation and the science behind preventing microbial contamination. This quiz covers topics such as pasteurization, sterilization techniques, and enzyme inactivation. Explore how temperature and treatment methods impact food safety and shelf life.
