Nutrition 3

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Questions and Answers

What is the primary purpose of food preservation?

To increase the nutritional content of food

To modify the appearance of food

To enhance the flavor of food

To prevent food wastage and degradation (correct)

How does food preservation contribute to seasonal food availability?

By promoting the consumption of frozen food only

By altering agricultural practices to ensure year-round harvest

By harvesting crops early before they ripen

By increasing the shelf-life of off-season fruits and vegetables (correct)

Which of the following is NOT a benefit of food preservation?

Preserving food quality

Decreasing food storage costs (correct)

Reducing food wastage

Preventing spoilage from microbial action

What role do enzymes and microbial pathogens play in food preservation?

They can cause food spoilage Signup and view all the answers

What is one of the outcomes of effective food preservation regarding food quality?

It retains the original color, texture, and flavor Signup and view all the answers

What leads to the change in the nutritional value of food due to microbial growth?

Presence of harmful bacteria Signup and view all the answers

Which factor is NOT involved in the autolysis process that contributes to food spoilage?

Microbial contamination Signup and view all the answers

What does oxidative spoilage primarily cause in food?

Rancidity or color changes Signup and view all the answers

Which of the following represents a biological factor contributing to food spoilage?

Growth of bacteria and fungi Signup and view all the answers

How does spoilage impact food safety?

Makes food harmful to consume Signup and view all the answers

At what temperature do all foodborne pathogens predominantly multiply and grow rapidly?

21 degree C to 49 degree C Signup and view all the answers

Which statement is correct about the temperature at which vegetative pathogens are killed?

They are killed at 74 degree C in a few seconds. Signup and view all the answers

What is the optimal temperature range for the growth of C. perfringens?

21 degree C - 46 degree C Signup and view all the answers

At which temperature are bacterial spores confirmed to be killed?

121 degree C Signup and view all the answers

What is the effect of maintaining food at 5 degree C?

Only a small number of bacteria can grow over weeks. Signup and view all the answers

What is the effect of keeping food at temperatures below 5°C?

It slows down microbial growth. Signup and view all the answers

Which of the following statements accurately describes the freezing process for food preservation?

Freezing does not prevent food spoilage bacteria from growing once defrosted. Signup and view all the answers

At what temperature is it safe to store food without significant microbial growth?

0°C Signup and view all the answers

What is the impact of a reduction in temperature by 10°C on the reaction rate of microorganisms?

It reduces the reaction rate by 1/3 to 1/2. Signup and view all the answers

What is the optimal temperature range for the growth of B.cereus?

21°C to 30°C Signup and view all the answers

What temperature range is typically maintained to kill most microorganisms in food preservation?

550C-750C Signup and view all the answers

What is the primary purpose of pasteurization?

To preserve food by killing harmful microorganisms Signup and view all the answers

What is a consequence of partial cooking of foods like meat and eggs?

It increases susceptibility to bacterial growth Signup and view all the answers

What must be done after the drying process to maintain the quality of dried food?

Completely seal the food to prevent moisture absorption Signup and view all the answers

Which method efficiently dries food in a cost-effective way using natural resources?

Dry sunny Signup and view all the answers

What is a primary characteristic of smoke in food preservation?

It contains antimicrobial properties. Signup and view all the answers

Which concentration of salt is effective in inhibiting the growth of microorganisms?

20% Signup and view all the answers

How does sugar contribute to food preservation?

By creating a high osmotic environment to remove moisture. Signup and view all the answers

What method involves using vinegar to preserve food?

Marinating Signup and view all the answers

What is one of the risks associated with smoking food as a preservation method?

Enhances the risk of cancer. Signup and view all the answers

What is the primary effect of pH adjustment during fermentation?

It facilitates the conversion of sugar into lactic acid. Signup and view all the answers

Which method effectively uses radiation for food preservation?

Ultraviolet radiation in cold storage. Signup and view all the answers

What is the significance of chemical and biological sterilization?

They eliminate all forms of microbial contamination. Signup and view all the answers

How does ionizing radiation contribute to food preservation?

It preserves food by killing microorganisms. Signup and view all the answers

What type of food preservation uses selective plant measures?

Biological measures. Signup and view all the answers

Study Notes

Food Preservation

Food preservation methods prevent food from spoiling by slowing down the growth of microorganisms and the food's own decomposition.
These methods extend the shelf life of food, making it available for longer periods.
Food preservation is crucial for:
- Reducing food waste.
- Ensuring food supply throughout the year, especially during periods of food scarcity.
- Accessing fruits and vegetables out of season.
- Transporting perishable food over long distances.
- Protecting food from enzymes and pathogens that cause spoilage.
Well-preserved food retains its quality, including color, texture, flavor, and nutritional value.

Food Spoilage

Food spoilage refers to the deterioration of food quality, impacting its nutritional value, texture, flavour, odour, and colour.
Spoiled food becomes unsuitable for consumption and can pose health risks.
The major bacteria responsible for food poisoning include Salmonella, Staphylococcus aureus, Bacillus cereus, Clostridium perfringens, Campylobacter, and Listeria monocytogenes.
Food spoilage can be attributed to various factors including:
- Microbial growth (bacteria, fungi, insects)
- Autolysis: decomposition caused by enzymes naturally present in food
- Oxidation: reaction with air causing rancidity (spoiling of fats) and colour changes
- Physical factors: freezing, burning, drying
- Chemical and biological factors
- Environmental factors
Food spoilage impacts the organoleptic quality (smell, touch, taste, sight) and can affect the nutritional value and safety of food.

Bacteria Growth Temperatures

Bacteria multiply rapidly at 21 degrees Celsius.
Some pathogenic bacteria can still multiply at temperatures up to 49 degrees Celsius.
Vegetative pathogens are killed within a few hours at 54 degrees Celsius.
Vegetative pathogens are killed in a few seconds at 74 degrees Celsius.
Bacterial spores are killed in minutes at 121 degrees Celsius.
The optimal temperature range for the growth of all foodborne pathogens is between 21 and 49 degrees Celsius.
C. perfringens thrives in the optimal temperature range of 21 to 46 degrees Celsius.
B. cereus thrives in the optimal temperature range of 21 to 30 degrees Celsius.
5 degrees Celsius is the generally recommended temperature for keeping food cold.
At 0 degrees Celsius, very few types of bacteria can grow over a few weeks in storage.
Most bacteria stop growing at 0 degrees Celsius.

Food Preservation Principles

Goal: To prevent microbial contamination, inhibit microbial growth, kill pathogens, and minimize food spoilage, infection, and poisoning.

Methods: Temperature Manipulation

Cooling:
- Temperature: +10°C, commonly used in homes.
- Effect: Slows microbial growth but does not completely prevent changes.
- Important: Proper air circulation, cleaning, and sanitizing of storage areas are crucial.
Freezing:
- Temperature: Below -18°C.
- Effect: Stops the multiplication of food spoilage bacteria. However, bacteria can grow during defrosting, potentially producing toxins.
- Important: Freezing does not improve food quality and choosing appropriate foods for freezing is essential.
Temperature Ranges & Microbial Growth:
- 21°C - 46°C: Optimal for growth of Clostridium perfringens.
- 21°C - 30°C: Optimal for growth of Bacillus cereus.
- 5°C: Generally recommended for cold food storage.
- 0°C: Only very few types of bacteria can grow over a few weeks at this temperature.

High Temperature Food Preservation

High temperatures (550°C - 750°C) effectively eliminate most microorganisms, except for spores and toxins.
Partial cooking can inadvertently increase the vulnerability of proteins in foods like meat, eggs, and dairy products to bacterial growth, favoring the multiplication of microorganisms and their toxins.

Pasteurization

Pasteurization is a heat treatment technique for preserving perishable foods like milk, involving temperatures below 100°C.
It involves heating milk to 63°C for 30 minutes or 72°C for 15 seconds to eliminate disease-causing microorganisms.
Cooling the milk down to 12.7°C immediately after pasteurization is crucial to prevent subsequent microbial growth.
Pasteurization, in combination with refrigeration, significantly extends the shelf life of milk.

Drying

Drying is a food preservation method that involves reducing the water content in food to below 15% to inhibit microbial growth.
Dried foods require airtight storage to prevent moisture reabsorption, which can promote microbial growth.

Drying Methods

Dry Sunny: This economical and effective technique utilizes sunlight and heat for drying.
Drying Dried: Involves drawing water out of food using heat, which is commonly used for preserving tea, meat, and fish.
High Pressure Drying: Removing water from food in a tube under high pressure and heat. It is typically used for milk powder production.
Low Pressure Drying: Involves drying food under reduced pressure, removing water through evaporation.
Other Drying Methods: Winter dried and steam smoke drying.
Cons of Drying: Drying can lead to a loss of nutrients, in particular vitamins like vitamin C and potential alterations in protein structure.

Steam Smoking

Steam smoking is a process that cooks, flavors, and preserves food by exposing it to smoke from burning wood.
The smoke acts as an antimicrobial and inhibitor.
Common foods smoked include meats and fish.
Different methods of smoking exist, such as hot smoking, cold smoking, smoke preparation, and smoke baking.
Smoking as a preservative may increase the risk of cancer.

Salt and Sugar Preservation

Salt and sugar are used in seasoning, collectively called curing, to remove moisture from foods like meat.
Pickling involves preserving food in brine (salt solution), vinegar (acetic acid), or oil.
Salt kills and inhibits the growth of microorganisms at a concentration of 20%.
Different pickling techniques include chemical pickling and fermentation pickling.
Industrial pickles may contain sodium benzoate or EDTA to increase shelf life.
Sugar is used in syrup form to preserve fruits or in crystallized form, such as candied peel and ginger.
Glazed fruits receive a superficial coating of sugar syrup.
Sugar is also used with alcohol to preserve luxury foods like fruits in strong drinks like brandy.

pH Adjustment

Fermentation involves using microorganisms to convert sugars into lactic acid.
This process typically takes 15-30 days and results in a pH between 3 and 4.5.

Canning and Bottling

This method preserves food by sealing it in sterile bottles and cans.
Food is cooked during the process, killing or weakening microorganisms.
The duration of cooking varies depending on the type of food.

Radiation

Ultraviolet radiation can reduce surface contamination on various foods.
It's used in cold storage units of meat processing plants.
Ionizing radiations, like gamma rays, are used to preserve certain vegetables, fruits, and spices following state and federal regulations.

Sterilization

Sterilization eliminates bacteria, fungi, yeasts, molds, etc., preventing contamination.
This allows for storage at ambient temperatures, extending the shelf life of food.
Sterilization methods:
- Chemical sterilization (food additives)
- Biological sterilization (Phytoncid in garlic)
- Physical factors

Biological Measures

Focus on selecting similar tree plants and their nutritional needs.

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Description

Test your knowledge on food preservation methods that help prevent spoilage and extend shelf life. This quiz covers techniques essential for reducing waste and accessing seasonal produce all year round. Discover how preservation impacts quality and safety.