2nd Term Week 2
Class: Primary 4 (Basic 4/ Grade 4)
Subject: Agricultural Science
Topic : Method of farm produce preservation
Previous Knowledge: Learners have a background knowledge of processing and preservation.
Reference Materials: Charts showing different methods of preservation of farm produce. Textbooks, pictures from internet.
Learning Objectives: By the end of the lesson, learners will be able to :
Define food preservation
identify methods of food preservation
Explains each method of food preservation
List examples of food preserved under each methods.
Content:
Food preservation is a way of keeping food crops from getting decayed or spoilt or the way of keeping food crops in a way that will prolong the life span of the food crop.
There is need to preserve food because if foods are not preserved it may lead to food spoilage.
Food preservation helps to make food hygienic and safe for future use. Preserved food items do not get contaminated and infected with insects and other pests of food.
There are different methods of preserving food crops and some of these methods include:
i. drying
ii. smoking
iii. salting
iv. frying
v. canning
vi. additives
vii. refrigeration
Drying: Drying is one of the ways of preserving food crops. It is a method that is mostly practised by people in the whole world because it does not require huge amount of money to practise. There are three basic methods of drying today:
(a) Sun drying: is a traditional method in which foods dry naturally in the sun. The seeds and food crops to be preserved are spread in the sun for it to be dehydrated, i. e. for water to be dried off.
(b) Hot air drying: is a method in which crops and seeds are exposed to a blast of hot air in order to reduce the moisture content of the crop.
(c) Freeze-drying: is a method in which frozen food is placed in a vacuum chamber to draw out the water. Removing the water preserves food because micro-organisms need water to grow.
Smoking: is usually done by placing foods on a wire gauze flame. Example of food that require smoking is fish.
Salting : is an act of using salt to preserve food. This can be done by rubbing salt all over the body of the food item. An example of food that requires salting for its preservation is meat.
Frying: is a process of preserving food by using oil to fry foods in order to prevent it from getting spoilt. Foods that may be fried include meat, fish, etc. Frying may be done using either palm oil or groundnut oil, frying pan is normally used to fry the food items.
Canning: is a method used to preserve a wide variety of foods, including soups, sauces, fruits, vegetables, juices, meats, fishes, and some dairy products. Canning preserves food by heating it in airtight vacuum-sealed containers. The can is filled with food, and air is pumped out of the space remaining at the top of the can to form vacuum.
The container is sealed, heated in cooker called a retort, and then cooled to prevent overcooking of the food inside. This process removes oxygen, destroys enzymes involved in food spoilage, and kills most micro-organisms that may be present in the food.
Canned foods are popular and may be stored for a long periods without refrigeration. However, because of the high temperatures required fir sterilization, canning affects the colour, texture, flavour and nutrient content of foods. Examples of canned foods are tin tomatoes, milk, milo, sardine, geisha, gems, butter, etc.
Refrigeration: is a modern way of preserving food crops. This is done or carried out with the use of a refrigerator. This method is advantageous because it fies not cause any chemical or physical changes to food. Foods that requires refrigeration methods include meat, fishes, eggs, milk, some fruits and some vegetables.
Additives: Food additives are chemicals that are added to food in small amounts. Direct additives are added deliberately during processing to make food look and taste better, maintain or improve nutritive value, maintain freshness, and help in processing or preparation. Some additives help preserve food by preventing or slowing down chemical changes and the growth of micro-organisms in food. Examples of additives include salt.
Presentation Step:
Step 1: The teacher introduces the lesson by revising the previous lesson taught with the learners.
Step 2: He then asked the learners, “what is preservation?”
Step 3: He then group the learners to discuss the various methods of preservation of farm produce.
Step 4: The learners representative then explains the various method of preserving farm produce.
Step 5: The teacher then rap up the lesson by buttressing the points listed by each group.
Evaluation: The teacher reviews the lesson by asking the following questions as follows:
1. Mention any four types of preservation methods that you know. ________________________, ________________________, ________________________, _________________________.
2. Give two examples of food crops that require (a) drying: _________________, _________________.
(b) frying: _________________, _________________.
3. What is canning? ____________________________________________________________________________________________
4. Refrigeration causes a chemical change to foods. ( True / False)
5. Give two examples of food crops that require canning. _________________, ____________________.
6. __________________ is the act of destroying micro-organism in food. (dehydration, sterilization)
Conclusion: At the end of the lesson, the learners were able to answer the questions correctly while the teacher makes some corrections.
Assignment:
1. Is retort a cooker? (Yes/ No)
2. Mention three types of drying as a method if preservation: _________________________, ___________________, __________________________
3. What is frying? ____________________________________________________________________________________________.
4. What are food additives? ____________________________________________________________________________________________