Grade 7 Q&A: Chapter 5: Food Safety

Concept Questions

Q1: What is food safety?

Answer: Food safety refers to the practices and conditions required to preserve food quality to prevent contamination and foodborne illnesses, ensuring that food is safe for consumption.

Q2: List three common causes of food spoilage.

Answer: Three common causes of food spoilage are: 1. Growth of microorganisms (bacteria, fungi like moulds and yeasts). 2. Action of natural enzymes present in food. 3. Chemical reactions like oxidation (e.g., rancidity).

Q3: What is the main objective of food preservation?

Answer: The main objective of food preservation is to stop or slow down food spoilage, prevent the loss of quality, edibility, or nutritional value, and thus allow for longer storage and availability of food.

Q4: Name three traditional methods of food preservation.

Answer: Three traditional methods of food preservation are drying, salting, and using sugar (e.g., in jams).

Q5: Explain the process of pasteurization. Who developed it?

Answer: Pasteurization is a food preservation method where liquid food (like milk) is heated to a specific temperature for a set period (e.g., 72°C for 15 seconds), and then rapidly cooled. This process kills harmful bacteria without significantly altering the food's taste or nutritional value. It was developed by Louis Pasteur.

Q6: What is food adulteration?

Answer: Food adulteration is the intentional act of debasing the quality of food by mixing or substituting inferior, cheaper, or harmful substances, or by removing valuable ingredients from it.

Q7: Give two examples of common food adulterants.

Answer: Two examples of common food adulterants are water added to milk, and stones or pebbles mixed with grains and pulses.

Q8: What are the health risks associated with consuming food adulterated with Metanil yellow?

Answer: Metanil yellow is a non-permitted dye used as an adulterant, particularly in turmeric powder or sweets. Its consumption is carcinogenic (cancer-causing) and can also affect the nervous system.

Q9: Why is it important to ensure food safety?

Answer: It is important to ensure food safety to protect public health by preventing foodborne illnesses, poisoning, and long-term health issues. It also ensures that food retains its nutritional value, reduces economic wastage, and builds consumer trust.

Q10: How does freezing help in food preservation?

Answer: Freezing helps in food preservation by lowering the temperature of food below 0°C. This extreme cold stops the growth of most microorganisms and significantly slows down enzymatic activity, thus preventing spoilage and extending the food's shelf life.

Q11: What is the purpose of using inert gas in food packaging?

Answer: The purpose of using inert gases (like nitrogen) in food packaging is to prevent oxidation of the food (which can cause rancidity or discoloration) and to inhibit the growth of oxygen-dependent microorganisms, thereby extending the product's freshness and shelf life.

Q12: Name two natural preservatives and how they work.

Answer: Two natural preservatives are: 1. **Salt:** Used in pickles and salted fish. It draws out moisture from food and creates a high osmotic pressure, inhibiting microbial growth. 2. **Sugar:** Used in jams and jellies. It also draws out moisture and creates a high sugar concentration, which prevents microbial spoilage.

Q13: What are some visible signs that food has spoiled?

Answer: Visible signs that food has spoiled include changes in color (e.g., mould growth, discoloration), unpleasant smell, sour or off-taste, changes in texture (e.g., sliminess, softness), and the presence of visible mould or slime.

Q14: How does canning preserve food?

Answer: Canning preserves food by first heating the food to a high temperature to destroy microorganisms and inactivate enzymes, and then sealing it in airtight containers. The airtight seal prevents re-contamination by microorganisms from the environment.

Q15: What is the risk of consuming edible oil adulterated with used engine oil?

Answer: Consuming edible oil adulterated with used engine oil poses a severe health risk because used engine oil is highly toxic and contains harmful chemicals and heavy metals that can cause severe poisoning and long-term health problems.

Textbook Exercise Solutions

A. Fill in the blanks:

1. The process of heating liquid food to kill harmful bacteria is called pasteurization.
2. Adding salt to pickles is a method of food preservation.
3. The intentional debasing of food quality is called adulteration.
4. Moulds and bacteria are examples of microorganisms that cause food spoilage.
5. The gas used to prevent oxidation in packaged snacks is nitrogen.

B. Match the following:

Column A

1. Drying
2. Refrigeration
3. Salting
4. Sugar
5. Canning

Column B

1. Jams
2. Fish
3. Grains
4. Milk
5. Vegetables

Answers:

1. Drying - Grains
2. Refrigeration - Milk
3. Salting - Fish
4. Sugar - Jams
5. Canning - Vegetables

C. Answer the following questions:

Q1: What is food spoilage? What are its causes?

Answer: Food spoilage refers to any undesirable change in food that makes it unfit for consumption, affecting its taste, smell, appearance, or texture. Its main causes include:

• Microorganisms: Growth of bacteria, yeasts, and moulds that break down food components.
• Enzymes: Natural enzymes in food that cause ripening and degradation.
• Chemical reactions: Such as oxidation (leading to rancidity in fats).
• Pests: Contamination by insects or rodents.
• Physical damage: Bruising or cutting that exposes food to spoilage agents.

Q2: Explain various methods of food preservation.

Answer: Various methods of food preservation include:

• Drying: Removing moisture (e.g., grains, dried fruits).
• Cooling/Refrigeration: Lowering temperature to slow microbial growth (e.g., milk, vegetables).
• Freezing: Lowering temperature below 0°C to stop microbial activity (e.g., meat, fish).
• Boiling: Heating to kill microorganisms (e.g., milk).
• Smoking: Using smoke to preserve and flavor (e.g., fish, meat).
• Use of Preservatives: Adding natural (salt, sugar, oil) or chemical (sodium benzoate) substances to inhibit microbes.
• Pasteurization: Heating and rapid cooling of liquids to kill pathogens (e.g., milk).
• Canning: Heating and sealing food in airtight containers (e.g., canned fruits).
• Use of Inert Gas: Flushing packages with gases like nitrogen to prevent oxidation (e.g., chips).

Q3: What is food adulteration? Give examples of common adulterants.

Answer: Food adulteration is the intentional act of reducing the quality of food by adding inferior, cheaper, or harmful substances, or by removing valuable components. Common examples of adulterants include:

• Water in milk
• Stones, pebbles, or sand in grains and pulses
• Brick powder in chili powder
• Metanil yellow (a non-permitted dye) in turmeric powder or sweets
• Chalk powder in flour or sugar
• Used engine oil in edible oil
• Papaya seeds in black pepper

Q4: Why is food safety important for our health?

Answer: Food safety is crucial for our health because it prevents foodborne illnesses, poisoning, and long-term health problems caused by contaminated or spoiled food. By ensuring food is safe, we protect ourselves from harmful bacteria, viruses, toxins, and adulterants that can lead to acute sickness or chronic health issues.

Q5: How can you detect adulteration in milk and chili powder at home?

Answer:

• Milk: To detect water adulteration, put a drop of milk on a polished slanted surface. If the milk flows down slowly, leaving a white trail, it is pure. If it flows quickly without leaving a mark, it is adulterated with water.
• Chili Powder: To detect brick powder adulteration, take a spoonful of chili powder in a glass of water. If brick powder is present, it will settle down at the bottom of the glass, while pure chili powder will largely remain suspended or float.

References

1. Maharashtra State Board 7th Standard Science Syllabus (Based on current curriculum for food safety)
2. Screenshot_2025_0527_233931.jpg (Provided content and exercise questions)