Nutrition - Topic 2: Biology Notes Form Two
Concepts of Nutrition and food Nutrients
Food Processing, Preservation and Storage.
The Concept of Food Processing , Food Preservation and Food Storage
Explain the concept of food processing , food preservation and food storage
Food
processing refers to all the ways in which food is treated in order to
make itedible, appetizing and safe to eat or to keep it fresh for a long
time.
Some of activities involved in food processing are;
- Picking, sorting and washing fruits and vegetables
- Cooking by boiling steaming, roasting backing or frying
- Converting raw materials into other products for example making cheersfrom milk or sugar from sugar cane
FOOD PRESERVATION
Food preservation refers specifically to the methods of food processing that areused to prevent food from spoiling or going bad
Methods of food preservation
- Keeping out micro organisms for example by canning or bottling
- Using high temperature to kill microorganisms that cause spoilage eg.By pasturalization and boiling
- Using very low temperature to slow down the growth of microorganisms for example refrigerationiv.
- Irradiation which is by using radiations such as gamma rays to killmicro organismsv
- Eliminating the moisture that is needed for growth of micro organismfor instance by drying, salting, smoking etc
- Adding chemicals such as salt sugar, carbon monoxide to preventphysical changes in food
FOOD STORAGE
Refers to the methods used to keep or reserve of food for future use.
Foodstorage can be done on a small scale at the family level for example in afamily granary or food store. Or large scale for large populations e.g ingovernment stores of grains.
The Importance of Food Processing, Preservation and Storage
Explain the importance of food processing, preservation and storage
The following are the importance of food preservation
- prevents wastage of food
- it saves money by preventing spoilage of food
- maintains the quality of food
- prevents the growth of micro organisms that can cause illness
- improve the flavor of food
- removes armful toxins and micro organisms from food
- makes food available even where they are not in season
- enables transportation of delecate and perishable food such as milk andfruit over long distance
Traditional and Modern Methods of Processing, Preserving and Storing Food
Differentiate between traditional and modern methods of processing, preserving and storing food
They are two methods of food processing and preservation which are;
- traditional methods
- modern methods
I. TRADITIONAL METHODS
These are methods used to process and preserve food which doesn’t require the use oftechnology.
These are methods used to process and preserve food which doesn’t require the use oftechnology. The following are the traditional ways.
CURING
It involves additional of substances such as salt, sugar, spaces and vinegar toanimal foods, moist meat and fish. Curing removes water making itunavailable for the growth of microorganism it also improve the taste of food.Sausages, becon and curried beef are made by curing meat.
DRYING IN THE SUN
Thus method is used to preserve rice, maize, cloves, banana, beans, peas,meat, fish etc.Here food is left for long time on the sun in order to reduce its moisturecontent. Reducing the amount of water in food discourages the growth ofmicroorganisms. Some food such as banana and cassava are cut into smallpieces to fasten the process.
SMOKING
Smoking is the traditional method which is used to reduce moisture content offood to prevent growth of microorganisms. Grains, meat, fish can be driedslowly over the smoking wood fire
COOKING
Traditional methods of cooking are simple and include boiling, steaming,backing, in hot hash and roasting. These processes help to soften food,improve flavor and preserve food. Example potatoes, bananas, and maize canbe boiled before being dried.
STORAGE IN GRANARIES AND PITS
Dry grains are stored in granaries which are usually raised above the ground.
The grains are sometimes mixed with neem leaf ash or groundnuts oil to further prevent attack by microorganisms.Granaries keep grains safe from insects rodents and birds. Example harvestedyams, potatoes and cassava can be stored in large pits in the ground after drying.
ADVANTAGES OF TRADITIONAL METHODS OF FOOD PROCESSING ANDPRESERVATION AND STORAGE
- They are simple and they can be done by most people
- They use locally available materials and simple technology thus keeping costslow
- No harmful chemicals are added to the food
- Curing and smoking add distinct flavor.
- Most methods do not destroy nutrients
DISADVANTAGES:
- Food can be preserved and stored for the limited period of time
- They are manual and thus difficult to apply on a large scale
- Traditional methods are highly limited in the variety of food that can beprocessed preserved and stored.
II. MODERN METHODS OF FOOD PROCESSING AND PRESERVATION
REFRIGERATION AND FREEZING
Is the temporary storage of food at low temperature of up to 4 centigrade inorder to slow down the growth of microorganisms. Freezing involves storingfood at very low temperatures in order to stop the growth of microorganisms .frozen food can be kept for months.Food that can be refrigerated include milk, fresh fruits, vegetables, juice andbutter. Freezing is mostly used for meat, fish, fruits and vegetables.
PASTEURIZATION
Thus method of preservation was named after its inventor Louis Pasteur. Itinvolved heating food to a very highest temperature for a short time in order tokill the micro organisms that can cause spoilage.Pasteurization maintains the nutrients content and flavor of food. Examples offood that can be pasteurized are milk and fruity juice.
CANNING AND BOTTLING
In this method, food is preserved by heating it in airtight vacuum, sealedbottles or cans. The container is filled with food then the air is pumped out toform a vacuum. The container is sealed and heated to kill microorganisms andenzymes but not enough to overcook the food. Food that can be bottled orcanned include tomatoes, fruits, juice, beef, fish and packed beans. Bottled orcanned food can be kept for months or even years.
USING ADDITIVES
This method involved the use of chemicals such as sodium benzoate, sodiumchloride, and vinegar are added to food to slow down the growth of microorganisms. This is commonly done to pressure fish and meat
DRYING
Food is dried by using either hot blast of air from a vacuum drayer. Afterdrying the food is then sealed in moisture –proof containers.
IRRADIATION
Is the modern method which involve the use of rays of energy to stop thegrowth of microorganisms in stored food. Example in onions, beans andpotatoes. This makes food last longer. It also prevents sprouting in onions andpotatoes.
ADVANTAGES OF MODERM MOTHODS
- Food can last for many months and even a year
- Modern methods can process, preserve, and store large variety of food.
- They are advanced technology bused in fast and can handle huge quantities of food.
DISADVANTAGES;
- The chemicals used can be harmful if eaten in excess
- These
- advanced technology involve means where they are used only in certain
- areas for instance refrigeration requires electricity.
- The process used for example canning and pasteurizing require special skills.
- Sometimes nutrients are lost thus lowering the nutritional value of food
DIFFERENCES BETWEEN TRADITIONAL AND MODERN METHODS OFFOOD PROCESSING AND PRESERVATION
TRADITIONAL METHODS | MODERN METHODS |
| Less costiful | High cost iful |
| It involves the use of low technology | It involves the use of advanced technology |
| It processes and preserves food for alimited amount of time | Preserves food for months and evenyears |
| It uses local materials to process and preserve food It is used by most people | It uses chemicals to process and preserve foodIt is used by few people |
| It select type of food to be processed and preserved | It is not selective |
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Biology Form II