NCERT Solutions for Class 5 EVS Chapter 4

Spoilage of food means a state of worsening of food in which the food does not remain suitable for human consumption. Thus, the spoiled food means that the food can no longer be taken as it has become worse or unfit for consumption.

The major cause of food spoilage is:
• its improper storage that is if we don’t not keep it properly. If we keep the food and vegetables in warm place, they will spoil quickly. So, whenever we bring such things, we should always store them properly in the refrigerator because low temperature helps in slowing down the growth of bacteria that spoils the food.
• Other factors that are responsible for food spoilage are bacteria, mould, yeast, moisture, light, temperature, and chemical reaction etc.

Food that gets spoiled develops an unpleasant odour. The taste and texture also gets spoiled. Spoilage can cause fruits and vegetables to get mushy, meat develops a bad odour. Other factors that cause food spoilage are bacterial infections, chemical and physical reactions which affect the taste, smell and appearance of the food.
Signs of food spoilage include an appearance which is different from the food when it is fresh
like changes in colour, texture with an unpleasant odour, or an undesirable taste. The item becomes softer than normal. If mold occurs, it can be seen on the food item.

Food items which would not get spoilt till one month are Pickles, Potato chips, Jams.

Food spoils more easily in summer months due to an increase in temperature, which causes bacteria to multiply. Vegetables, milk or any food product which contains high moisture gets spoiled quickly in summer. Food also gets spoiled quickly in rainy season which has high moisture conditions.

The conditions which help the germs to grow and spoil the food are:
• high moisture content
• high temperature
• humidity
• Cooked food is kept open
• Milk is not boiled properly
• Pickles are not kept safe from moisture or air.

To make mamidi tandra,the following method is followed:
• a mat, casuarina, poles, string made of coconut husk, some jaggery and sugar are arranged
• Then it is placed in a sunny spot in the backyard where they make a high platform by using poles and mat.
• Then the mangoes are peeled and the pulp is extracted.
• The juice is collected in a vessel.
• The pulp is strained through a fine muslin cloth and the fibre is removed.
• After that sugar is added with crushed jaggery in equal amounts in the pulp and mixed thoroughly.
• The mixture is spread into a thin layer over a mat and left to dry in the sun.
• The mat is covered with a clean saree every evening to avoid any dust.
• Then another layer of mixture is prepared by following the same steps until it grows thick like a golden cake.
• And after four weeks it is ready to eat.

Food which is spoilt by microorganisms contains contaminated and poisonous substances which are released by the microbes. The spoilt food is not only bad in taste but it also releases foul odour. If we eat such food it will lead to food poisoning. Food-borne illness, are a result of food poisoning, caused by eating contaminated, spoiled, or toxic food. The most common symptoms of food poisoning include nausea, vomiting, and diarrhea, pain in abdomen, fever and headache.

When food items like bread are kept outside for many days especially during the rainy season, it gets spoiled as fungus develops on it which are green spots on the bread. They start growing on the surface of bread as they get the conditions of darkness and moisture. This change in colour tells that the bread has got spoilt.

Sugar and jaggery are mixed into the mango pulp to give it a sweet taste and then the mixture is dried in sun to make it thick by removing all the water content present in it.

Food preservation is the process of treating and handling food in such a way so as to stop or slow down spoilage to prevent foodborne illness and maintaining nutritional value, texture and flavour.

We need to preserve the food due to following reasons:
• prevent spoilage of food
• prevent microbial growth
• prevent contamination of food
• kill pathogens
• reduce food poisoning

Some preservatives used in the kitchen are salt, spices, vinegar, and sugar have been used to preserve foods for centuries.

Some ways in which the fruits and vegetables can be preserved are-
• Drying
• Canning.
• Pickling.
• Fermenting.
• Freezing
• Oil Packing.
• Salting.

We should check the following things while buying packed food item:
• It has no holes, openings, or tears in the packet.
• safety seals are not broken. We should not buy those packed foods whose seal is damaged or tampered.
• Ensure that we don’t buy cans that have dents or are rusted, or bulging, or have an opened seal

While purchasing perishable food items we should:
• Make a point to check the date written on perishable foods, especially the chilled or frozen food items.
• See the ‘use-by’ date which shows the date by which a product should be consumed or it will expire.
• Ensure that it should is not being sold after that date.
• Check the best before date which tells the date till which the food will remain at its best quality and can be consumed.

The glass jars and bottles should be dried well in the sun before we fill or keep something in them like pickle etc. to remove the moisture content that is present in the jar and micro-organism present too. We need to dry the can or jars to ensure that the food items being kept in them do not get attacked by bacteria and fungus due to the water content available in them. The moisture present in them can allow bacteria and other microorganisms to grow so we need to dry the bottles in sunlight. Moreover, the pickles if stored in containers having moisture can spoil it. Thus, Jars and bottles should be dried properly before filling them with pickles to make them moisture free because if there is moisture left in them then it will result in the growth of microorganisms leading to the spoilage of pickles

Making mamidi tandra need s a lot of hard work and time too. It needs at least four weeks of hard work. It has to be dried by keeping it in the sun and all safety measure have to be taken to prevent it from getting spoiled due to ants or harmful pathogens and dust when it is kept under the sun. It is a work in which all the family members have to work together as a team.

Sugar is a good preservative as it helps in preserving the colour, texture and flavour of the food item. Sugar that is added in jams and jellies helps in forming a gel and increasing the flavour too. When we add large amount of sugar, in any recipe, it acts as a preservative by preventing microbial activity and thus helps in preserving the food items for a longer period of time.

Salt is an effective preservative as it helps in reducing the water activity of food which is the amount of limitless water available which is favourable for the growth of microbes and chemical reactions.
Salting is thus a method of preserving the food with dry salt which is fit for human consumption. Salt is used for preservation because most of the bacteria, fungi and other organisms cannot survive if we add salt at a higher quantity to the food.

Using Oil is a good preservation method because it provides an airtight closure to the ingredients and expands their shelf life too. On the basis of the recipe and especially for seafood, preserving through salting as well as cooking or marinating in oil is helpful.

We should dry the grain properly before storing them because if we store the freshly harvested grains without drying, then they may get spoilt due to organisms and lose their germination capacity. Therefore, before storing them, the grains need to be properly dried under the sun so that we can reduce the moisture content present in them.

We need to preserve certain food items because food preservation prevents the growth of microorganisms (such as yeasts), or other microorganisms (bacteria or fungi) which spoil the food as well as slows the oxidation of fats.

Pickles and chutneys are made from unripe mangoes. Aam papad is made from ripe mangoes. Mango shake is also made from ripe mangoes.

Different methods of food preservation are as follows:
• Drying- Drying is a method of dehydrating the food is a method of food to remove moisture from the food so that bacteria, yeast and molds cannot grow and spoil the food.
• Refrigeration- Refrigeration helps in preserving food items like fruits and vegetables as it can store food at low temperature and slow down the spoilage and natural metabolic processes. Meat, fish products and precooked foods which have limited life can be preserved by this method.
• Fermentation- It is the process in which a substance is broken down into a simpler substance. Various microorganisms like yeast and bacteria usually play a role in the fermentation process eg- making bread, yogurt and other foods.
• Canning- It is the process which involves keeping food in jars and heating them at a temperature which destroys the microorganisms that could cause food spoilage. Canning also disables enzymes that could cause the food spoilage.
• Pasteurization- It is a process of which involves heating a liquid and then cool it for some time to kill the bacteria present in it. It is used to make the food safe to eat. People pasteurize dairy products and other foods to make them germ free. The process is named after Louis Pasteur who invented this method of food preservation.
• Freezing- It is a method to stop spoilage and keep the foods safe. It prevents the microorganisms from growing fast as it slows down the enzyme activity that causes food spoilage. Thus, the water in the food freezes into ice crystals and becomes unavailable to the microorganisms which need it for growth.
• Chemical preservatives- They are some common antimicrobial preservatives which reduce the microbial spoilage of food by preventing the growth of bacteria, yeasts, and molds.

Fruits and vegetables are kept in refrigerator because cold temperature helps the food to stay fresh for a longer time period. Refrigeration helps to slow down the activity of bacteria (which all food contains) so that it takes longer for the bacteria to spoil the food.

Before buying curd we would keep in mind the following:
• Price,
• Date of Manufacturing,
• Expiry Date,
• Weight
• Ingredients used to make it.
• Name of the company

Pickles and chutneys are made from unripe mangoes. Aam papad is made from ripe mangoes. Mango shake is also made from ripe mangoes.

If a food item is “perishable which means a food that should be refrigerated to prevent bacteria from multiplying at room temperature is left out overnight then the food will develop a bad smell, there will be a change in its taste and texture. The food will be contaminated if it is left out more than two hours at room temperature as microorganism will grow and spoil the food.

Food grains like rice, wheat and pulses should be cleaned first to remove dirt out and then stored in closed tight containers. Keeping the food grains in closed tight containers protects them from micro-organisms, rats, cockroaches, ants and other insects and thus they can be stored for longer times without any spoilage. This method of preservation is called Drying and proper storage.

If we eat spoiled food, we suffer from food poisoning. The food that is spoiled contains germs like bad bacteria or toxins which can cause diarrhoea and an upset stomach.

Vinegar is used for all type of food preservation methods. It helps in slowing or stopping food from spoiling for long periods. It is mainly the pH or acidity of vinegar that prevents the bacterial growth and this process is most commonly called pickling.

The milk which is spoiled has a different smell which is sour due to lactic acid produced by bacteria. It becomes slightly yellow in colour and has a lumpy texture.

Juices available in the market do not get spoiled for many months if not opened because they have preservatives in them which helps in increasing their life. Some juices which are made up of all fruits spoil quickly than juices with added sugar and preservatives as the natural sugars in the fruit begins to ferment over time.

Jams and jellies do not get spoiled for long periods because they contain lots of sugar in them which prevents the growth of bacteria and spoilage. High sugar content is a good way of preserving food. Thus, jams and jellies are preserved using natural preservative (Sugar) and synthetic ones as well (eg – Sodium Benzoate – Class II Preservative).

Boiling milk is an effective method of killing the germs present in milk. Boiling makes the milk free from disease-causing organisms. Although it does not remove all impurities, it does kill most of the dangerous bacteria and other organisms.

Ripe mango are the mangoes which have more juice and less fibres as compared to the other mangoes. So, the ripest mangoes are chosen to make the mamidi tandra or aam papad.

We can preserve cooked rice by cooling and refrigerating it as quickly as possible. When it becomes cold we should put it into a container, cover it and chill in the fridge. Keep the rice for not more than a day before reheating it and reheat it only for one time.

Fungal growth on bread is called Rhizopus.