Saturday, March 5, 2016



Children in this lesson we are going to learn about Spoilage and wastage of food,preservation of food(drying and pickling).

Food spoilage means the original nutritional value, texture, flavour of the food are damaged, the food become harmful to people and unsuitable to eat.
There are three types of microorganisms that cause food spoilage -- yeasts, moulds and bacteria. 
yeasts and moulds can thrive in high acid foods like fruit, tomatoes, jams, jellies and pickles.
Bacteria are round, rod or spiral shaped microorganisms. Bacteria may grow under a wide variety of conditions. There are many types of bacteria that cause spoilage.
Fungal Spoilage: Blue mould rot in tomato caused by Penicilliumi spp,
Watery soft rot in apple caused by Sclerotinia sclerotiorum.
Bacterial Spoilage: Soft rot in tomato caused by Erwinia carotovora.
Enzymes are proteins found in all plants and animals. If uncooked foods are not used while fresh, enzymes cause undesirable changes in colour, texture and flavour. Enzymes are destroyed easily by heat processing.
Oxidation by air:
Atmospheric oxygen can react with some food components which may cause rancidity or color changes.
Microorganisms, specifically bacteria, molds, and yeasts, can cause food to spoil. For example, microorganisms that break down fats in unsalted butter can cause it to become rancid. Bacteria that breaks down protein in meat (proteolytic bacteria) and results in foul odors.

Biji returned the bread:
Aman’s Biji went to the market to buy bread. The shop was very crowded. The shopkeeper picked up a packet of bread and gave it to Biji. She looked at it and returned it immediately.
How does food get spoilt?
The whole class can do this experiment together. Take a piece of bread or roti. Sprinkle a few drops of water on it, and put it in a box. Close the box. See the bread or roti everyday until you find some changes on it.
Make this table on a chart paper and put it up in the classroom. Fill up the chart every day after discussing the changes seen.
So children the fod gets spoiled easily.bacteria and fungi grow well at room temperature in the presence of moisture. Cereals and pluses do not get spoiles easily as there is no moisture in them.
Spolit food it unfit for consumption. It taste bad and can causes disease.
Therefore, it has to be prevented from spoilage. This prevention is termed as preservation.
Food can be presrved by the following methods. We can stored food by this following five methods.
1. Cooling Or Refrigeration
2. Jellying
3. Pickling
4. Drying Or Dehydration
5. Tetra packing
6. Canning
1. Cooling Or Refrigeration: food spoiling bacteria do not grow in cold temperature. So, this is a common way of preservation.
2. Jellying: fruits like strawberries, mangoes and pine apples are preserved by this method. The fruit pulp is a boiled in sugar syrup. Sugar acts as a preservative. Jams and fruits are preserved in this way.
3. Pickling: seasonal fruits like mangoes, lime, amla and garlic are preserved by pickling. For this we add `salt, vinegar and oil are used as preservatives in pickles.
4. Drying Or Dehydration: the food can also be preserved by drying in the stem. Spices like chillies and ginger, papadas and food grains are preserved by drying in the sun. Dry means removing the moisture content of the food which promotes the growth of bacteria.
5.Tertra packing : this method is similar to canning but is used for liquids. Here, the food is heated to very high temperature and then packed in terapacks .
Ex: milk, juice, oil, and ghee are stored in this way.
6. Canning: in this process the food is heated temperature to kill the food spoiling bacteria and then stored in air tight cans or bottles.
Food preserved helps in preventing wastage of food from the spoiling. It also helps us to store food and use it when it required whole the year. All preserved foods have a shelf life. While buying and using preserved food, we should check the expiry date mentioned at the label of the product.
Summer treat – Mamidi tandra:
Chittibabu and Chinnababu live in Atreyapuram town in Andhra Pradesh. The brothers spend the summer holidays playing in the mango garden, when the trees are full of fruits. They also like to eat unripe mangoes with salt and chilly powder.
At home, their mother cooks unripe mangoes in different ways. She also makes many kinds of mango pickles. The pickles last through the year until the next mango season. One evening, while having food Chinnababu asked, “Amma, we have so many mangoes. Make some mamidi tandra (aam papad) from them.”
Their father said, “Making mamidi tandra needs four weeks of hardwork. If you both promise to help us everyday for the next four weeks, we can together make the mamidi tandra.”
Both the brothers quickly agreed to help. The next day both the children went to the market with their father. They bought a mat woven from the leaves of a palm tree, poles of casuarinas tree, string made of coconut husk, some jaggery and sugar. Amma found a sunny place in the backyard. Both the brothers made a high platform by using poles. They spread out and tied the mat on that platform.
The next day, Appa chose the most ripe mangoes.  They took out the mango pulp into a large pot. Then they strained the pulp through a fine muslin cloth, to remove the fibres from the pulp.
Then Chittibabu crushed the gur (jaggery) till there were no lumps. They added the jaggery and sugar in equal amountsto the pulp.
Chinnababu mixed the jaggery and sugar well with a big spoon. Amma then spread this pulp into a thin layer over the mat. The thin layer was left to dry in the sun. In the evening, they covered the mat with a clean saree to avoid any dust.
The next day they again took out some mango pulp. They added jaggery and sugar into the pulp. Then they spread the pulp over the previous day’s layer. This work was given to both the brothers. Both of them together spread many layers over it.
For the next four weeks they hoped that it would not rain. For four weeks, they added layer after layer until the jelly grew four centimetres thick and looked like a golden cake.
After some days Amma said, “The mamidi tandra is ready, we can
take it out and cut it into pieces tomorrow.” The next day, the mat was brought down from the platform.
Mamidi tandra was cut into smaller pieces. The brothers tasted it. It was tasty. Chhinnababu said, “Wow, how tasty! After all we have also helped in making it.”


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