Food safety | Class 7 | Science | Chapter 5 | Maharashtra State Board
In this video, we will be discussing the various aspects of food safety and how you can ensure that the food you eat is safe and healthy. We will start by discussing food spoilage and the factors responsible for it. We will also look at the quantitative and qualitative wastage of food and discuss ways to prevent both. Moving on, we will talk about food storage and preservation. We will discuss the various methods of food protection like freezing, smoking, use of insecticides, irradiation, use of inert gas, use of preservatives, and pasteurization. We will also explore the topic of food adulteration and how it can affect your health. We will look at common ways in which food is adulterated and how you can find out if the food you are eating has been adulterated. By the end of this video, you will have a good understanding of the various aspects of food safety and how you can ensure that the food you eat is healthy and safe. So, sit back, relax, and enjoy the video.
Questions & Answers
1. Complete the following statements by using the correct option from those given below.
(Irradiation, dehydration, pasteurization, natural, chemical)
Drying the food grains from farms under the hot sun is called dehydration.
Materials like milk are instantly cooled after heating up to a certain high temperature. This method of food preservation is called pasteurization.
Salt is a natural type of food preservative.
Vinegar is a chemical type of food preservative.
2. Answer the following questions in your own words.
(a) How is milk pasteurized?
Ans. 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 pasteurization of milk.
(b) Why should we not consume adulterated food materials?
Ans. 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?
Ans. Our parents take following care to keep foodstuffs safe:
Drying of grains.
Boiling of milk, soups and curries from time to time.
Refrigeration of vegetables, fruits, milk and cooked food.
Candying of jams.
Use natural preservatives like oil, spices, neem leaves, salt, etc.
Use chemical preservatives in sauces, ketchups, pickles, jams and squashes.
(d) How does food spoilage occur? Which are the various factors spoiling the food?
Ans. Food spoilage is the process by which food deteriorates to the point where it is no longer edible for humans, or its quality of edibility becomes significantly reduced.
The following factors contribute to food spoilage:
Bacteria cause food to spoil.
Incorrect storage can lead to food spoilage.
Infestation by pests can spoil food.
Chemical reactions can occur in food, causing spoilage.
(e) Which methods of food preservation would you use?
Ans. I use following methods to preserve the food:
Freezing
Boiling
Salting of pickles
Drying of grains
Candying of jams.
3. What shall we do?
(a) There are vendors selling uncovered sweetmeats in open places in the market.
Ans. 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-puriwalla’ is serving the pani puri with dirty hands.
Ans. 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.
Ans. We should keep them in refrigerator because in refrigerator, due to low temperature, fruits and vegetables do not spoil and biological and chemical reactions in fruits and vegetables are slowed down at low temperature.
(d) We need to protect foodstuffs from pests like rats, cockroaches, wall-lizards, etc.
Ans. If we do not protect foodstuffs from pests like rats, cockroaches, wall-lizards etc. then the food get spoiled by them and germs carried by them enters into the food. If we eat this food then we may get food poisoning and we fall sick so we need to protect foodstuffs from pests like rat, cockroaches, wall lizards etc.
4. Find the odd-man-out.
(a) Salt, vinegar, citric acid, sodium benzoate.
Ans. Salt. (Salt is natural preservative. Others are chemical preservatives.)
(b) Lakhi dal, brick dust, metanil yellow, turmeric powder.
Ans. Turmeric powder. (Turmeric power is natural ingredient. Others are food adulterants.)
(c) Banana, apple, guava, almond.
Ans. Almond. (Almond is a dry fruit. Others are natural fruits.)
(d) Storing, freezing, settling, drying.
Ans. Settling. (Settling is the odd one out because rest of the three are preservation methods.)
5. Complete the chart below.
Foodstuff | Adulterant | |
1. | Turmeric powder | Matanil 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.
Ans. 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 of food.
2. Store grains and other perishable foodstuffs like vegetables, fruits, milk etc. using proper methods.
3. Wash fruits and vegetables before cutting it.
(b) The cooked rice is underdone.
Ans. Sometimes in a hurry if we cook the rice it is underdone.
Possible remedies: Use proper pressure cooker to cook the rice.
(c) The wheat that was bought is a bit moist.
Ans. 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 in a clean and dry container to avoid microbial growth.
(d) The taste of yoghurt is too sour/slightly bitter.
Ans. 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 refrigerator to avoid biological and chemical reactions in food materials.
(e) Cut fruits have turned black.
Ans. 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 on fruits.
6. Give reasons.
(a) Food remains safe at 5° Celsius.
Ans. Food remains safe at 5° Celsius because at 5°C, micro-organisms stop growing.
(b) Nowadays, food is served buffet style during large gatherings.
Ans. 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.
E X T R A
1. Fill in the blanks.
16th October is celebrated as “World Food Day”.
FSSAI means - Food Safety and Standarization Authority of India.
Nitrogen gas is filled in tight packets of potato wafers.
Common name of acetic acid is Vinegar.
Malathions is sprayed on the gunny bags containing food grains.
Aluminium phosphide is used in smoking method.
X-rays and gamma rays are emitted by radioactive isotopes in irradiation method.
Louis Pasteur found the pasteurization method.
Metanil yellow adulterant is added to turmeric powder.
Brick dust adulterant is added to red chilly powder.
Calcium carbide is used to make fruits more attractive.
Carbonated soda and phosphoric acid harmful chemicals are mixed with cold drinks.
Shopkeepers change the of the expiry date food packets to avoid a financial loss.
Milk vendors add urea to the milk to appear as higher fat content.
The shelf life of potatoes and onions increases due to slowed-down of sprouting.
Serving too much food to guests at traditional feasts and banquets leads to quantitative wastage of food.
Miscalculation of the time required to transport food from producers to consumers leads to qualitative wastage of food.
Prevention of food spoilage by microbial growth and infestation by pests is called food protection.
2. Give Scientific Reasons.
(a) Refrigerators are used in the kitchen.
Ans.
Biological and chemical reactions in food materials are slowed down at low temperature.
As a result food remains in good condition for a longer period. Therefore refrigerators are used in the kitchen.
(b) Potatoes and onions are treated with gamma rays.
Ans. Potatoes and onions are treated with gamma rays because irradiation with gamma rays prevents their wastage due to sprouting and increases their shelf life.
(c) Grains are sun-dried.
Ans. Grains are sun-dried to preserve them because on sun drying their water content gets reduced and hence they last longer.
(d) We boil milk from time to time.
Ans. We boil milk from time to time to kill microorganisms in it and thus prevent it from getting spoilt.
(e) Jams or pickles get spoilt if their jars are not sealed properly.
Ans. If the jar is not sealed properly, micro-organisms from the air enter in the jar and start growing on the food. Oxygen in the air helps the micro-organisms and fungi to grow faster and hence bring about the spoilage of the jams and pickles.
(f) Some vendors add urea to the milk.
Ans. Some vendors add urea to the milk so that it appears to have higher fat content.
(g) Food wastage should be avoided.
Ans. In countries like India, the food requirement is plenty and people do not get proper meals even once in a day. If food is not wasted then it could have met the need of many others. Therefore, food should not be wasted and proper measures should be implemented to stop quantitative and qualitative wastage of food.
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