Week 1 and 2 – SS1 Second Term Food and Nutrition Notes

SIGMA TERM (2nd)
FOOD AND NUTRITION
SSS 1
SCHEME OF WORK FOR SIGMA TERM
1.     Revision scientific study of foods.

1. Measurement: units of measurement.
2. Effects of heat on food.

2.     Food tests (tests for carbohydrates, protein and fats),
–    The food composition table.
–    Meal planning.
3.     Reproductive health.
4.    Reproductive health –malnutrition e.g. Over nutrition and under nutrition.
5.    Kitchen management.
6.    Kitchen plan/ layout.
7.    Kitchen equipment.
–    Materials used in making kitchen equipment.
8.     Cleaning agents and abrasives.
9.     Safety in the kitchen.

1. Methods of handling kitchen equipment properly, precautions to prevent accident.
2. Contents and use first aid box.
3. Treatments of simple injuries e.g. Cuts, burns and scalds.

10.    Hygiene.

1. Personal- rules of personal hygiene in the kitchen.
2. Kitchen hygiene rules.

11.    Revision.
12.     Examination.

 
 WEEK 1
TOPIC: Scientific study of food
CONTENTS;
Units of measurement
Energy value of food can be measured in calories or joules but a large unit of energy is measured in kilo-calories. It is the most common unit of measuring energy. The international unit of energy is “joule“. Therefore kilocalories is the amount of heat required to rise the temperature of a thousand gram (1000) of water by 1 degrees Celsius. For example one gram (gm.) of carbohydrate will produce four kilocalories of energy. One gram of protein will produce four kilocalories of energy and one gram of fat will produce nine kilocalories of energy.
Food weight: the raw or processed food can be measured in grams or kilograms.
1000 grams = 1 kilogram.
The macro nutrients are measured in grams while the vitamin and trace elements are measured in smaller units because they are required in relatively small quantity by the body and are also present in food in a small quantity.
Vitamins and trace elements are measured in milligrams (mg.) and micrograms ( g.).
1g     =    1000mg (10³mg)
1gm        =    1 000, 000 g (10⁶ g)
Or
1mg        =    0.001 or 10^-3gm
1 g        =    0.000001gm or 10^-6gm
Other units often used in measuring vitamins are the international unit (I.U) and standard unit (S.I).

 
 EFFECTS OF HEAT ON NUTRIENTS
Effects of heat on carbohydrates

1. They are dextrinized i.e. broken down into simpler units and therefore easier to digest.
2. In moist heat, carbohydrates gelatinize i.e. they expand and burst and thereby making them more digestible.
3. They caramelize i.e. turn brownish. This is usually produced with dry heat.

Effects of heat on proteins

1. Heat denature protein i.e. it alters the primary structure and state of the native protein e.g. egg, beans.
2. The protein contracts and the food shrinks e.g. meat.
3. If the protein is overcooked it becomes tough and indigestible e.g. fried fish.

Effects of heat on fats and oil

1. Fat changes from solid state to liquid state when heated.
2. When oil is heated to a temperature of between 200⁰ -210^{0 F}, the oil produces a blue haze which signifies the smoke point, at the “smoke point”, the oil may catch fire.
3. When the oil is heated beyond smoke point, it decomposes to produce a poisonous substance known as acrolein.

Evaluation: mention the various measurements used for food stuffs

• What is the measurement of energy value of carbohydrates and vitamins.
• State the effect of dry heat on carbohydrates.

Assignment: state the metric equivalent of the following; a. evaporated milk

1. Satchet fat         c. a gallon of vegetable oil         d. a bag of rice
2. A pack of spaghetti

    

 WEEK 2
TOPIC: food tests
CONTENTS;
IDENTIFICATION OF FOOD NUTRIENTS
Carbohydrates

1. Iodine test: cut a section of carbohydrate food to expose the flesh. Then pour drops of iodine on the exposed flesh. If it turns black or darkish brown, it shows the presence of carbohydrate. If it remains light brown, then carbohydrate is absent.
2. Litmus test: this is another simple experiment to detect the presence of carbohydrate in any food substance. The food item is peeled if it has any bark.it is then grated and made into a paste. Red litmus paper is immersed into the paste, if it turns blue it shows the presence of carbohydrate but if it remains unchanged, it does not contain any carbohydrate.

Proteins

1. Foam test: a very simple test for the presence of protein, is todissolve the food substance in water and shake vigorously. If a foam is produced, it shows the presence of protein. Absence of foam indicates that the food substance does not contain protein.
2. Alcohol test: alcohols have a coagulating effect on proteins. Thus if a food product or its solution coagulates, shrinks or curdles when immersed in alcohol, it shows that food is proteineous. In the case of meat apart from shrinking, its color also changes to brown.
3. Million’s test: million’sreagent may be used to detect the presence of protein in foodstuffs. A solution of the foodstuff is warmed with million’s reagent (which contains mercurous and mercuric nitrates in nitric acid). If protein is present, a white precipitate which later turns red is obtained. The only common protein which does not give a positive result with this test is gelatin.

Fats
Blotting paper test: the presence of fat in any foodstuff can be detected bygrinding a small quantity of foodstuff between two pieces of blotting or filter paper. If after grinding, the paper or some portion on it becomes translucent or greasy, it shows the presence of fats or oil in the foodstuff. If not, it indicates the absence of fat.

 FOOD COMPOSITION TABLE
Food composition table is a table that shows in a tabular form the nutritive value (amounts of nutrients) of common food commodities be they raw, processed or cooked.
A food composition table serves many purposes. The purposes are as follows.

1. Gives ready and useful information about the nutritive values of the major food commodities thereby preventing misinformation of consumers by processors and marketers of food.
2. It is used to compare the food values of one food with another and helps consumers to choose foods according to their needs.
3. It is used for planning meals which meet specific needs for specific groups of people such as infants, adolescents, aged etc.
4. It is used to calculate the nutritional contents of food with a view to comparing them with standards in order to determine whether a food meets Recommendation Daily Allowance (RDA) for nutrients or not.

The food composition table is affected by the following factors:

1. The nature and type of the soil used to grow the commodity.
2. The variety of the plant or breed of the animal.
3. The age of the animal will affect the composition of meat and milk obtained from them.
4. The type of feed given to animal and poultry livestock will also affect the composition meat, milk and eggs from these animalsand birds.
5. The climatic condition during the growth of plants.
6. The handling and storage methods.

Evaluation: state the purposes of the food composition table

• State the disadvantages of food composition table

Assignment: Read Meal planning