Class 7 Science Solution: Lesson No. 5 – Food Safety (Science Class 7th) [Maharashtra State Board]
Class 7 Science Solution : Textbook Questions and Answers:
1) Complete the following statements by using the correct option from those given below.
(Irradiation, dehydration, pasteurization, natural, chemical)
Q a) Drying the food grains from farms under the hot sun is called …………..
Answer: dehydration
Q b) Materials like milk are instantly cooled after heating up to a certain high temperature. This method of food preservation is called …………
Answer: pasteurization
Q c) Salt is a ……….. type of food preservative.
Answer: Natural
Q d) Vinegar is a …………. type of food preservative.
Answer: chemical
2. Answer the following questions in your own words.
(a) How is milk pasteurised?
Answer: Boil the milk at 80°C for 15 minutes and cool it quickly. This destroys the microbes present in the milk and it can remain for a longer duration. This process is called the pasteurisation of milk.
(b) Why should we not consume adulterated food materials?
Answer: Different types of adulterants affect our health in different ways. Some adulterants cause abdominal discomfort or poisoning while some may affect the functioning of some organs if consumed over a long period of time or even cause cancer.
(c) What precautions do your parents take to keep foodstuffs safe?
Answer: Our parents take the following care to keep foodstuffs safe
1. Drying of grains.
2. Boiling of milk, soups, and curries from time to time.
3. Refrigeration of vegetables, fruits, milk, and cooked food.
4. Use chemical preservatives in sauces, ketchup, pickles, jams, and squashes.
5.. Use natural preservatives like oil, spices, neem leaves, salt, etc.
(d) How does food spoilage occur? Which are the various factors spoiling the food?
Answer: Food spoilage is the process in which food deteriorates to the point in which it is not edible to humans or its quality of edibility becomes reduced.
Following are the factors for spoiling food:
1. Bacteria causes food to spoil.
2. Incorrect storage may spoil the food.
3. Infestation by pests.
4. Chemical reaction takes place in food and it gets spoiled.
(e) Which methods of food preservation would you use?
Answer: I use the following methods to preserve the food:
1. Freezing
2. Boiling
3. Salting of pickles
4. Drying of grains
5. candying of jams.
3. What shall we do?
(a) There are vendors selling uncovered sweetmeats in open places in the market.
Answer: We should tell them to sell the covered sweets because uncovered sweets are harmful to eat because it contains dust, dirt, and germs. And buyers also should not purchase these uncovered sweets.
(b) A ‘pani-puriwala’ is serving the panipuri with dirty hands.
Answer: We should tell him to wear gloves before serving panipuri because dirty hands contain dirt and germs which are harmful to us.
(c) We have purchased a large quantity of fruits and vegetables.
Answer: We should keep them in the refrigerator, due to low temperatures, fruits and vegetables do not spoil and biological and chemical reactions in fruits and vegetables are slowed down at low temperatures.
(d) We need to protect foodstuffs from pests like rats, cockroaches, wall lizards, etc.
Answer: 1. If we do not protect foodstuffs from pests like rats, cockroaches, wall lizards, etc. then the food gets spoiled by them and germs carried by them enter into the food.
2. If we eat this food then we may get food poisoning and fall sick so we need to protect foodstuffs from pests like rats, cockroaches, wall lizards, etc.
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: Storing
5. Complete the chart below.
Answer:
| Sr. No. | Foodstuff | Adulterant |
| 1. | Turmeric powder | Metanyl 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 of food happens due to wrong methods of protecting food, excessive use of food preservatives, over-cooking, washing the vegetables after cutting them, mis¬handling of fruits like grapes and mangoes, miscalculation of the time required to transport food from producers to consumers are some of the reasons of qualitative wastage of food.
Possible remedies:
1. Avoid overcooking food.
2. Store grains and other perishable foodstuffs like vegetables, fruits, milk, etc. using proper methods.
3. Wash fruits and vegetables before cutting them.
(b) The cooked rice is underdone.
Answer: Sometimes in a hurry if we cook the rice it is underdone.
Possible remedies: Use a proper pressure cooker to cook the rice.
(c) The wheat that was bought is a bit moist.
Answer: Sometimes due to sudden rain, wheat gets a bit moist.
Possible remedies: Do not store the moist wheat, it gets spoiled due to fungus so first sundry it and then store it in a clean and dry container to avoid microbial growth.
(d) The taste of yoghurt is too sour/slightly bitter.
Answer: The taste of yoghurt is too sour/slightly bitter means it is spoiled. This happens if it is not kept in the refrigerator.
Possible remedies: Always keep the yoghurt in the refrigerator to avoid biological and chemical reactions in food materials.
(e) Cut fruits turned black.
Answer: Fruit contains an enzyme called polyphenol oxidase or tyrosinase that reacts with oxygen. The oxidation reaction basically forms a sort of rust on the surface of fruits so it turns black.
Possible remedies: 1. Coat the fruits with sugar syrup.
2. Add lemon juice to fruits.
7. Give reasons.
1) Food remains safe at 5° Celsius.
Answer: Food remains safe at 5° Celsius because, at 5°C, micro-organisms stop growing.
2) Nowadays, food is served buffet style during large gatherings.
Answer: Nowadays, food is served buffet style during large gatherings because due to buffet style quantitative wastage of food can be avoided, as people take only as much as they could eat.
Class 7 Science Solution: 5 – Food Safety
Answer the following questions:
Q.1. How and where food is wasted?
Answer: Quantitative wastage of food:
1. Wrong methods of farming like hand sowing of, ts seeds, inadequate threshing, improper storage and wrong methods of distribution are some reasons for quantitative wastage of food.
2. Besides, much food is wasted as a result of the custom of offering and serving too much food to guests at traditional feasts or banquets.
3. Had it not been wasted, all this food could have met the need of many others Qualitative wastage of food: Using wrong methods of protecting food, excessive use of food preservatives, over-cooking, washing the vegetables after cutting them, mis-handling of fruits like grapes and mangoes, mis-calculation of the time required to transport food from producers to consumers, are some of the causes of quantitative wastage of food.
Q.2. How is the food adulterated?
Answer: Food is adulterated in the following ways:
- Removal of some important components of food. e.g. removal of the fat content of milk, the essence of cloves, cardamoms, etc.
- Mixing of a low-quality inedible or cheaper material or harmful colour with food.
- Mixing of some harmful materials like small stones, fine sand, iron filings, urea, dung of horse, sawdust etc.
How will you find out if food has been adulterated?
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