Std. 7 Science Chapter 5 Food Safety Exercise Answers | Maharashtra Board
Std. 7 Science – Chapter 5: Food Safety
1. Complete the following statements.
Options: Irradiation, Dehydration, Pasteurization, Natural, Chemical
(a) Drying the food grains from farms under the hot sun is called dehydration.
(b) Materials like milk are instantly cooled after heating up to a certain high temperature. This method of food preservation is called pasteurization.
(c) Salt is a natural type of food preservative.
(d) Vinegar is a chemical type of food preservative.
2. Answer the following questions in your own words.
(a) How is milk pasteurized?
Answer: Milk is heated to a certain high temperature and then cooled quickly. This process is called pasteurization.
(b) Why should we not consume adulterated food materials?
Answer: We should not consume adulterated food because it may contain harmful substances and can cause health problems.
(c) What precautions do your parents take to keep foodstuffs safe?
Answer:
- They keep food covered.
- They store food in clean containers.
- They keep perishable food in the refrigerator.
- They protect food from insects and pests.
- They check the expiry date of packaged food.
(d) How does food spoilage occur? Which are the various factors spoiling the food?
Answer: Food spoils mainly due to microorganisms like bacteria and fungi. Heat, moisture, air, insects and improper storage can also spoil food.
(e) Which methods of food preservation would you use?
Answer: I would use refrigeration, drying, salting, pasteurization, canning and suitable preservatives for preserving food.
3. What shall we do?
(a) There are vendors selling uncovered sweetmeats in open places in the market.
Answer:
We should not buy uncovered sweetmeats. We should ask the vendors to keep the food covered and protected from dust, flies and insects.
(b) A ‘pani-puriwalla’ is serving the pani puri with dirty hands.
Answer:
We should avoid eating food served with dirty hands. We should ask the vendor to wash his hands and maintain proper hygiene.
(c) We have purchased a large quantity of fruits and vegetables.
Answer:
We should store fruits and vegetables properly. Perishable fruits and vegetables should be kept in the refrigerator to prevent spoilage and wastage.
(d) We need to protect foodstuffs from pests like rats, cockroaches, wall-lizards, etc.
Answer:
We should store foodstuffs in clean, dry and airtight containers. The storage area should also be kept clean to prevent pests.
4. Find the odd-man-out.
(a) Salt, vinegar, citric acid, sodium benzoate
Answer: Salt
(b) Lakhi dal, brick dust, metanyl yellow, turmeric powder
Answer: Turmeric powder
(c) Banana, apple, guava, almond
Answer: Almond
(d) Storing, freezing, settling, drying
Answer: Settling
5. Complete the chart below.
| S.No. | Foodstuff | Adulterant |
|---|---|---|
| 1. | Turmeric powder | Metanil yellow |
| 2. | Black pepper | Dried papaya seeds |
| 3. | Rava | Iron filings |
| 4. | Honey | Sugar, water and jaggery |
6. Explain why this happens and suggest possible remedies.
(a) Qualitative wastage of food.
Answer:
Qualitative wastage occurs due to overcooking, improper storage and improper handling of food.
Remedies:
- Avoid overcooking food.
- Store food properly.
- Wash fruits and vegetables before cutting them.
- Use suitable methods of food preservation.
(b) The cooked rice is underdone.
Answer:
The rice is underdone because it has not been cooked sufficiently. It should be cooked properly using sufficient water.
(c) The wheat that was bought is a bit moist.
Answer:
Moist wheat may develop fungus and get spoiled.
Remedy:
The wheat should be dried properly in the sun and stored in a clean, dry and airtight container.
(d) The taste of yoghurt is too sour/slightly bitter.
Answer:
The yoghurt may have spoiled due to improper storage or exposure to warm conditions.
Remedy:
Yoghurt should be kept in the refrigerator. Spoiled yoghurt should not be consumed.
(e) Cut fruits have turned black.
Answer:
Cut fruits turn black because the substances in the fruits react with oxygen in the air. This process is called oxidation.
Remedy:
We can add lemon juice to the cut fruits and cover them properly.
7. Give reasons.
1. Food remains safe at 5°C.
Answer:
Food remains safe for a longer time at about 5°C because the growth of microorganisms is greatly slowed down at low temperatures.
2. Nowadays, food is served buffet style during large gatherings.
Answer:
Food is served buffet style because people can take only as much food as they need. Thus, quantitative wastage of food can be reduced.
Important Points for Examination
| Topic | Remember |
|---|---|
| Natural preservative | Salt |
| Chemical preservative | Vinegar |
| Food at 5°C | Microorganisms grow slowly |
| Blackening of cut fruits | Oxidation |
| Buffet style | Reduces food wastage |
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