General Science Solutions Solutions for Class 7 Science Chapter 5 Food Safety are provided here with simple step-by-step explanations. These solutions for Food Safety are extremely popular among Class 7 students for Science Food Safety Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the General Science Solutions Book of Class 7 Science Chapter 5 are provided here for you for free. You will also love the ad-free experience on Meritnation’s General Science Solutions Solutions. All General Science Solutions Solutions for class Class 7 Science are prepared by experts and are 100% accurate.

Page No 39:

Question 1:

Complete the following statements by using the correct option from those given below.
(Irradiation, dehydration, pasteurization, natural, chemical)
(a) Drying the food grains from farms under the hot sun is called .......... .
(b) Materials like milk are instantly cooled after heating up to a certain high temperature. This method of food preservation is called .......... .
(c) Salt is a .......... type of food preservative.
(d) Vinegar is a .......... type of food preservative.

Answer:

(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.

Page No 39:

Question 2:

Answer the following questions in your own words.
(a) How is milk pasteurized?
(b) Why should we not consume adulterated food materials?
(c) What precautions do your parents take to keep foodstuffs safe?
(d) How does food spoilage occur? Which are the various factors spoiling the food?
(e) Which methods of food preservation would you use?

Answer:

a. Milk is pasteurised in order to kill any kind of harmful microorganism present in it and to increase its shelf life. Pasteurisation is a process in which the milk is heated to a certain temperature for a fixed period of time and then is quickly cooled. For example, it may be heated at 80oC for 15 minutes and then immediately cooled. This helps to kill any kind of microorganism which is present in milk. 

b. The process of substituting or concealing the quality of food, adding harmful or poisonous substances to food, and misbranding or giving false labels to food is known as food adulteration. the adulterants which are added to food products have harmful effects on our bodies. For example:
  • vegetable oil is adulterated with cheaper and non-edible oils such as argemone oil which causes dropsy, which in turn leads to renal and cardiac failure.
  • pulses are mixed with kesari dal or with metanil yellow to improve the colour which can cause carcinogenic disorder and it can also affect the nervous system.
We should be very careful in buying our food products and should be aware of our rights and actions which can be taken against people who are involved in this crime.

c. Precautions which are taken to preserve foods:

1. Storing fruits and vegetables in proper storage, for example, fruits like bananana are not stored in refrigerator while fruits like mangoes require refrigerator.
2. Storing grains, dals etc. in dry conditions and in air proof containers.
3. Making pickles and jams to increase their shelf life.

d. The undesirable or disagreeable change in the state of food which makes it unsuitable for human and animal consumption is termed as food spoilage. Spoilage of food can be caused by various factors like:
  • Microorganisms: Growth of microorganisms like bacteria, fungi etc. can lead to spoilage of food. 
  • Action of enzymes: Enzymes which are an inherent part of plant and animal tissue begin the decomposition process after the death of plant or animal. For example, a bananana starts to ripen and then spoil if it is not consumed on time.
  • Infestation by insects: Insects like cockroaches may infest the food stuff and make them unsuitable for consumption. There is possiblity of transmission of pathogens from these insects.
  • Wrong handling of products may also result in the spoilage of foodstuffs.
  • Overcooking is another such reason for spoilage of foods.

e. The following methods of food preservation can be used:
  • Preservation by common salt: Common salt is usually used to preserve meat and fish as it checks the growth of bacteria in these foods. It is also used to preserve amla, raw mangoes, and tamarind.

  • Preservation by sugar: Sugar is usually used to preserve jam, jellies, and squashes. Sugar prevents spoiling of food by reducing the moisture content of food, which inhibits the growth of bacteria in it.

  • Preservation by oil and vinegar: Oil and vinegar are used to preserve vegetables, fruits, fish, and meat. They prevent food from getting spoilt as micro-organisms cannot grow in such an environment.



Page No 40:

Question 3:

What shall we do?
(a) There are vendors selling uncovered sweetmeats in open places in the market.
(b) A 'pani-puriwalla' is serving the pani puri with dirty hands.
(c) We have purchased a large quantity of fruits and vegetables.
(d) We need to protect foodstuffs from pests like rats, cockroaches, wall-lizards, etc.

Answer:

a. We should not eat food from vendors who sell uncovered foods. We should try to talk to him and convince him to keep his food covered while selling it. Also, we should tell him the importance of clean and healthy food and how these habits can help him to gain profit for his business.

b. If a pani puriwalla is serving the pani puri with dirty hands, then we should not consume it. We sholud insist him to wash his hands and wear gloves while serving the pani puris.

c. If we have purchased large amounts of fruits and vegetables, then we need to store them properly. Some of the fruits can be used to make juices, jams and jellies which would increase their shelf life and also make it easy to store food. Vegetables can be cut and stored in deep freezers and then used as and when required. Some vegetables can also be used in making pickles.

d. Foodstuffs can be protected from rats, cockroaches etc. by storing them in proper conditions and proper areas. They should be stored in air tight containers and away from damp places which are the breeding places for these organisms.

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Question 4:

Find the odd-man-out.
(a) salt, vinegar, citric acid, sodium benzoate
(b) lakhi dal, brick dust, metanyl yellow, turmeric powder
(c) banana, apple, guava, almond
(d) storing, freezing, settling, drying

Answer:

(a) salt, vinegar, citric acid, sodium benzoate- salt is the odd one out beacuse it is natural preservative while rest of them are chemical preservatives.

(b) lakhi dal, brick dust, metanyl yellow, turmeric powder - turmeric powder is the odd one out because it is a type of spice while the rest of the three are adulterants.

(c) banana, apple, guava, almond- almond is the odd one our because it is a dry fruit whereas the rest of the three are fresh fruits..

(d) storing, freezing, settling, drying- settling is the odd one out because rest of the three are preservation methods.
 

Page No 40:

Question 5:

Complete the chart below.
 

S.No. Foodstuff Adulterant
1. ---------- Metanyl yellow
2.  Black pepper ----------
3. ---------- Iron filings
4.  Honey ----------

Answer:

S.No. Foodstuff Adulterant
1. Turmeric powder Metanyl yellow
2.  Black pepper Papaya seeds
3. Rava Iron filings
4.  Honey Sugar

Page No 40:

Question 6:

Explain why this happens and suggest possible remedies.
(a) Qualitative wastage of food.
(b) The cooked rice is underdone.
(c) The wheat that was bought is a bit moist.
(d) The taste of yoghurt is too sour/slightly bitter.
(e) Cut fruits have turned black.

Answer:

a. Wastage of food can either be qualitative or quantitative. Qualitative wastage of food is caused by:

  • excessive use of preservatives
  • over cooking of food
  • washing vegetables after cutting them
  • using wrong methods of protecting food
  • mishandling of food products like fruits etc.
Qualitative wastage of food can be prevented by adopting steps like controlling the use of peservatives, taking care while cooking food to prevent it from being overcooked or undercooked, using proper methods of storage etc.

b. If the cooked rice is underdone, it can be used to make some foodstuff in which it can be reused. For example, underdone rice can be used to prepare kheer in which it can be cooked further with milk, or it can further be cooked to make papads or something else which would avoid its wastage.

c. If the wheat which was brought was little moist, it could be dried under the sun to remove this moisture. It is important to remove this moisture before grinding the wheat or storing it because it can act as a factor for the growth of microorganisms leading to its spoilage.

d. The taste of yoghurt could turn a little sour because it has undergone too much fermentation. The first thing would be to store this yoghurt in cold environment to stop further souring of the yoghurt. This yoghurt can then be used to make sweet lassi or some other delicacy like sindhi curry. 

e. Cut fruits turn black due to oxidation. Small amount of lemon juice should be applied to the surface of cut fruits as it prevents the oxidation of the fruits. 

Page No 40:

Question 7:

Give reasons.
1. Food remains safe at 5° Celsius.
2. Nowadays, food is served buffet style during large gatherings.

Answer:

a. Food remains safe at 5oC because this temperature prevents the growth of microorganisms. Microorganisms usually require hot and humid places to grow whereas at this temperature they cannot grow and survive. Their metabolic activities are inhibited at this temperature.

b. Nowadays, foods are served in buffet style during large gatherings to prevent the wastage of food. Every indivisual can choose what to eat and how much to eat according to their wish and thus prevents the wastage of food.



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