Topic 2: Nutrition - Biology Notes Form Two

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Topic 2: Nutrition – Biology Notes Form Two

Concepts of Nutrition and food Nutrients

Meaning of nutrition

Nutrition is the process by which organisms take in and use nutrients.

Nutrients are any substances that nourish an organism.

Food is any material when taken in absorbed and utilized meet requirement ofplant and animal body.

The Concepts of Nutrition and Food Nutrients

Explain the concepts of nutrition and food nutrients

FUNCTION OF FOOD

Oxidized to release energy
Used in growth of cells
Used to repair lost cells and tissue

TYPES OF NUTRITION

There are two main types of nutrition: autotrophic nutrition and heterotrophic nutrition.

Autotrophic Nutrition Is the process by which organisms manufacture their own food from simpleinorganic substances like carbon and hydrogen using either light energy(photosynthesis) or chemical energy (chemosynthesis)

Heterotrophic Nutrition Is the process in which organisms get nutrients by eating other organisms

The Importance of Nutrition in Living Things

Outline the importance of nutrition in living things

IMPORTANCE OF NUTRITION

Prevent diseases
Helps growth and development of cells, tissue and organs
It helps to repair damaged parts
It helps to protect the body against infection and diseases

Nutrition in Mammals, Human Nutrition

Human Nutrition

Human Nutrition is the provision to obtain the essential nutrients necessary to support life and health.

Are several types of food substances that are needed by the human body for itsproper functioning.

The basic food substances include proteins, carbohydrates, lipids, vitamins,minerals, roughage and water.

Different Types of Food Substances and their Functions in Human Body

Identify different types of food substances and their functions in human Body

PROTEINS

These are substances, which contain elements oxygen and nitrogen.

SOURCE OF PROTEINS

Foods such as Meat, liver, eggs, beans, milk, cheese, peas, groundnuts and mushrooms are good sources of protein.

FUNCTION OF PROTEINS

The following are the function of protein

It is used in body building
Used by body for tissue growth and repair such as healing of wounds and replacement of skin
Used as a source of energy, especially when the body lacks carbohydrates and lipids
It enables red blood cells to transport oxygen in our bodies

CARBOHYDRATES

Carbohydrates are mainly made of carbon, hydrogen and oxygen

SOURCES OF CARBOHYDRATES

Foods such as maize, rice, bananas, potatoes, cassava, wheat (bread, cake) and yams are rich in carbohydrates.

FUNCTIONS OF CARBOHYDRATES

The following are the function of carbohydrates

They are chief source of energy
In plants they are stored as starch
In animals they are stored as glycogen

LIPIDS

These are compounds of carbon, hydrogen and oxygen. They are insoluble in water. Lipids are made up of fatty acid and glycogen

SOURCES OF LIPIDS

Foods such as fish, nuts, seed oils, avocados and olives are good sources of lipids.

FUNCTIONS OF LIPIDS

Lipids are used as a source of energy
Protect the organs such as heart and kidneys

VITAMINS

Vitamins are chemical substances in small amounts that are used to maintain thebody.

Vitamins can be grouped into two categories: water-soluble and fat-soluble vitamins.

Fat-Soluble Vitamins can be stored in the body. Examples of fat-solublevitamins are Vitamins A, O, E and K

Water-Soluble Vitamins are not stored in the body. Vitamins B and C are water soluble.Vitamin B is of various forms, namely Vitamin B1, B2, B6 and B12.

SOURCES, FUNCTIONS AND SIGNS OF VITAMIN DEFICIENCIES

VITAMIN	SOURCE	FUNCTION	SIGN OF DEFICIENCY
Vitamin A(Retinol)	Liver, Milk Carrots,Orange and Yellow Vegetables	Essential for the formation of membranes of the eyes and the respiratory tract	– Night blindness- Increased risk of infections
Vitamin B1(Thiamine)	Lean meat,liver, eggs,tomatoes,yeast extract sand brown rice	Carbohydrates metabolism of all foods and release of energy to cells	– Beriberi- Loss of Appetite – Muscle cramps- Heart failure
Vitamin B2(Riboflavin)	Liver,meat,wholegrain,cereals,yeast extracts	Needed for metabolism of all foods and release energy to cells	– Cracks and sores around the mouth and nose- Visual problems
Vitamin B6(Pyridoxine)	Meat,vegetables,yeast extracts,whole grain cereals	Essential in protein metabolism	– Nerve irritability- Sores in the mouth and eyes- Anaemia
Vitamin B12(Cyanocobalamin)	Fish, meat,eggs, milk and liver	Builds genetic materials, help to form red blood cells	– Anaemia- Nerve damage- Weight Loss
Vitamin C(Ascorbic Acid)	Pawpaw,Citrus fruits,Fresh Green,vegetables,tomatoesandpotatoes	– Increaseresistant to diseases.- Improve absorption of iron.- Used insynthesis ofcollagen in thebones and gums
Vitamin D(Calciterol)	Egg yolk,milk, oilfish andliver	Helps to build and maintain teeth and bones	– Rickets in children- Osteoporosis (soft bones) in adults
Vitamin E(Tocopherol)	Sunflower oil, butter,brown rice and peanuts	– Antioxidant- Preventsdamage of cellmembrane	– Nerve abnormalities- Infertility in rats
Vitamin K	Green vegetables and liver	Needed for normalblood clotting	Defective blood coagulation resulting in excessive bleeding.

MINERALS

Certain mineral elements are vital for the proper functioning of the body.

Someare required in relatively large quantities and therefore called macro mineralsand others are required in very small quantities and are referred to as micro

Macro minerals include calcium, phosphates, potassium, iron, zinc, sodiumchlorine and magnesium.

Micro minerals include iodine, fluoride, manganese and copper.

Examples of minerals, their source and their function in the body

MINERAL	SOURCE	FUNCTION	SIGN OF DEFICIENCY
Calcium	Milk,Cheese,eggs andgreen vegetables	– Helps build strong bones and teeth- Important inclotting of blood	– Weak bones- Bleeding easily
Phosphates	Meat, Milk,Fish, Eggs and nuts	– Builds bones and teeth- Helps in muscle and nerve activity	– Poor bone and teeth formation
Potassium	Peanuts,bananas,orange juice and green beans	Needed for nerve and muscle function	– Poor muscle contraction
Iron	Liver,kidney,beans and green vegetables	Essential for making hemoglobin	– Anemia
Zinc	Meat, yeast	Helps to heal wounds	– Skin problems
	extrac tsand crab
Sodium	Table salt	– For nerve and muscle activity	– Muscle cramps
Chlorine	Table salt	Formation of hydrochloric acid in the stomach	– Poor digestion of protein
Magnesium	Spinach,pumpkin seeds, black beans	– Relaxation of nerves and muscles- Strengthening of bones	– Muscle weakness- Irregular heartbeat- Weak bones
Copper	Meat, fish and liver	Activation of enzyme	– Anemia- Bone and joint problems
Manganese	Kidneys,liver, tea,coffee, nuts and fruits	Formation of bones	– Nausea- Dizziness- Loss of hearing
Iodine	Iodized table salt and sea food	Production of thyroid hormones which regulate growth	– Goitre (enlarged thyroid gland)

ROUGHAGE

– This is dietary fiber that is obtained from the indigestible parts of plants.

SOURCES OF ROUGHAGE

Foods such as fruits, beans, cabbage, spinach, cassava, and whole baked potatoesare good sources of roughage.

FUNCTIONS OF ROUGHAGE

It helps in the passage of food and feces through the gut by aidingcontraction of the gut muscles

WATER

This is a compound containing element hydrogen and oxygen

SOURCES OF WATER

Rainfall, Rivers, Springs etc.

FUNCTIONS OF WATER

Used in digestion of food
Used in transport of material in the body
Used as solvent in chemical reaction

The Concept of Balanced Diet in Terms of Food Quality and Quantity

Explain the concept of balanced diet in terms of food quality and quantity

A BALANCED DIET

Meaning of balanced diet: A balanced diet refers to food containing all types of food nutrients in the correctproportions. We should eat a diet low in fats, sugars and salts but high in protein,carbohydrates, vitamins, minerals and roughage. More importantly we shouldtake in large amounts of water.

IMPORTANCE OF A BALANCED DIET

In order for the body to function properly, different food substances are requiredto do different works for example:

Carbohydrates provide energy
Vitamins needed to keep the body healthy
Minerals are needed for protection against diseases
Water is a universal solvent

Nutritional Requirement for Different Groups of People

Explain nutritional requirement for different groups of people

NUTRITIONAL REQUIREMENTS FOR DIFFERENT GROUPS OF PEOPLE

The following nutritional requirement

Expectants: There diet should contain more protein and minerals (Calcium (Ca) and Iron (Fe))

Lactating Mothers: Their requirements are like those of expectants butin greater amount to feed the body

Children: Require a lot of proteins for growth and development of body tissue.

The elderly People: They require adequate amounts of vitamins and minerals to maintain their health

Sedentary workers: These are individuals who stay in one place for along time while performing their daily occupational activities. Due to their lifestyle and occupation,obesity is increasingly common among them, they limit their intake of food rich in lipids.

Sick people: They need special and plenty of nutrients to help recover their health, those who have incurable diseases such as HIV/AIDS should get food that will help them to manage their conditions. They need to take plenty of fruits and water.

Different Types of Nutritional Deficiencies and Disorders in Human Beings

Outline different types of nutritional deficiencies and disorders in human beings

NUTRITIONAL DEFICIENCIES AND DISORDERS

Malnutrition

This is the condition, which occurs when one fails to feed on a balanced diet. Itmay be too little or eating only one type. These deficiencies and disordersinclude obesity, rickets, kwashiorkor, marasmus and anorexia nervosa.

Nutritional Disorders

These are conditions of ill health in a person, which arise as a result of lifestyle.

The Causes, Symptoms, Effect and Control Measures of Nutritional Deficiencies and Disorders

Explain the causes , symptoms, effect and control measures of nutritional deficiencies and disorders

Causes of Malnutrition

There three cause of mulnutrition

Eating too little
Eating too much
Eating one type of food

Effects of Malnutrition

Excessive feeding causes obesity
Under nutrition causes deficiency diseases

CAUSES, SYMPTOMS, EFFECTS AND PREVENTION MEASURES OF NUTRITIONAL DEFICIENCIES AND DISORDERS IN HUMAN BEINGS

DISEASE	CAUSES	EFFECTS	SYMPTOMS	PREVENTION
Kwashiorkor	Shortage of protein in diet	– Poor growth- Diarrhea- Loss of appetite- Pale skin- Dry skin- Change colour and texture- Body becomes weak and stomach protrudes	– Consumption offoods rich in protein
Marasmus	– Lack of and equate amount of food- Ignorance of balanced diet preparation of food, food hygiene	– Weight loss- Slowed growth-Decrease dactivity- Lac k of energy – Shrunk enbuttocks		– Getting adequate amounts of food – Balanced diet
Rickets	Lack of vitamin D,Phosphates and Calcium		– Bow legs- Knock knees- An odd shaped skul- Deformed spine	– Provide food rich with vitamin D,Phosphates and Calcium
Scurvy	Lack of vitamin C		– Pain in joints- Stunted growth- Bleed in gums	– Provide diet which containsfruits- Avoid prolonged cooking
Goitre	Lack of iodine		– Swelling of the thyroid gland	– Provide iodized salt and water(H2O)

Digestive System in Human

DIGESTIVE SYSTEM IN HUMAN BEINGS

The digestive system of human refers to the human alimentary canal and theorgans and glands associated with it.

Parts of the Human Digestive System and their Adaptive Features

Identify parts of the human digestive System and their adaptive features

THE MAIN PARTS OF ALIMENTARY CANAL

The main parts are:- Mouth, Oesophagus, stomach, small intestine, (duodenumand ileum), large intestine (colon) and rectum.

ADAPTATIONS OF STOMACH TO ITS MODE OF FUNCTION

Stomach has sphincter muscles to prevent food from flowing back into the oesophagus
Stomach has gastric glands, which produce gastric juice for the digestive process.
Also in the stomach of a young baby there is renin which coagulates milk
Stomachs have mucus which protects it from corrosion by digestive enzymes
There is hydrochloric acid for the emulsification of fats and killing ofbacteria

ADAPTATIONS OF ILLEUM TO ITS FUNCTIONS

The following are the adaptations of ileum to its mode of functions:-

It has secretory glands, which produce digestive enzymes
It is connected to the liver by the bile duct which enable the bile to reach ileum
It has finger like projections called villi for the absorption of food
The ileum is very long to ensure sufficient absorptions of food
The villi have large network of blood capillaries for transporting absorbed food to all parts of the body
The inner lining of the ileum is folded to increase the surface area forabsorption

The Digestion Process in Human Being

Explain the digestion process in process in human being

DIGESTION PROCESS IN HUMAN BEINGS

Digestion is the process by which food is broken down into a form that can beabsorbed and used by the body.

Digestion process involves two processes, which are mechanical break down offood and chemical break down of food. The mechanical break down of food takesplace in the mouth where the food is chewed by teeth so as to reduce it into smallpieces.

Digestive enzymes achieve chemical break down of food. The digested food isabsorbed and assimilated in the body.

The digestion process starts in the mouth where food is mechanically brokendown by teeth.

The presence of food in the mouth stimulates the salivary glandto produce more saliva.

FUNCTIONS OF SALIVA

Have salivary amylase enzyme that converts starch into maltose
To moisten the food
To provide medium for enzyme reactions
Have mucus to lubricate food for easy swallowing
Saliva consists of Sodium and Calcium salt to ensure alkaline mediumfor amylase enzyme

Difference Between the Human Digestive System with that of Other Mammals

Compare the human digestive system with that of other mammals

DIFFERENCES BETWEEN HUMAN DIGESTIVE SYSTEM AND RUMINANTS’DIGESTIVE SYSTEM

The ruminants’ digestive system differs from human digestive system in thefollowing ways:

Ruminants have more elaborate system to enable cellulose digestion
The stomach of ruminants have four chambers (rumen, reticulum,omasum, abomasum)
The food is regurgitated, chewed, and again then passed to omasum.

Common Disorders and Diseases of the Human Digestive System

Outline common disorders and diseases of the human digestive System

DISORDERS AND DISEASE OF THE DIGESTIVE SYSTEM

These include diseases and disorders that affect teeth, oesophagus, stomach,small intestine and large intestines

Examples are:- dental caries, heart burn, ulcers, constipation and flatulence.

Dental caries

This is commonly referred to as tooth decay. It occurs when bacteriadestroy the outer part of the tooth.

Heart burn

Refers to the burning or painful sensation in the oesophagus. It is caused by regurgitation of hydrochloric acid in the stomach which leads to the irritation of oesophagus.

Stomach ulcers

Refers to the sore in stomach lining. It is caused by erosion of stomachwall due to enzyme reactions.

Constipation

Refers to the decrease in frequency of formation of stool. It occurswhen the stool becomes dry and hard due to excessive waterabsorption in the colon.

Flatulence

This is caused by excess gas in the digestive tract

Causes, Symptoms, Effects and Control Measures of Common Disorders and Diseases of the Human Digestive System

Explain causes, symptoms, effects and control measures of common disorders and diseases of the human digestive system

SYMPTOMS OF DENTAL CARIES

Tooth ache
Holes in the teeth

CONTROL MEASURES TO CARIES

Regular brushing of teeth
Damaged teeth can be filled with artificial crown
Minimization of intake of foods rich in sugar
Avoid eating very hot or cold foods
Have regular dental check ups

SYMPTOMS OF STOMACH ULCERS

Burning pain in the stomach
Nausea and vomiting
Tiredness and weakness
Blood in vomit or stool

CONTROL MEASURES TO STOMACH ULCERS

Medication
Avoid smoking
Avoid taking alcohol
Avoid eating acidic foods

SYMPTOMS OF CONSTIPATION

Lack of bowel movements for two or three days
Hard stools
The urge to go for long call even after you have just been to the toilet

PREVENTION OF CONSTIPATION

Eat enough fibre
Drink enough water
Exercise regularly
Seek medical help

CAUSES OF FLATULENCE

Swallowed air
Eating food that causes gas such as beans, cabbage, milk and onions
Poor absorptions of carbohydrates

SYMPTOMS OF FLATULENCE

Abdominal pain
The constant urge to pass wind
Excessive belching
Accumulation of gas in the stomach

PREVENTION OF FLATULENCE

Avoid foods that produce gas
Chewing food properly
Limit the amount of food which are

Nutrition in Plant, Mineral requirement in Plants

Essential Mineral Element in Plant Nutrition

Mention essential mineral element in plant nutrition

The mineral requirement in plant growth are categorized into two groups:

Micro nutrients or minerals
Macro nutrients

Macro nutrients are minerals that are required in a large quantity for the plant growth.

They include Nitrogen, phosphorus, potassium, sulphur, sodium, magnesium, carbon, hydrogen,and oxygen.

Micro nutrients; these are nutrients that are required in small amount for the plantgrowth.

They include; iron, cobalt, fluoride, silicon, iodine, copper and zink

The Roles of Essential Elements in Plant Nutrition

Investigate the roles of essential elements in plant nutrition

The role of essential mineral elements in plant nutrition

element	role	Deficiency
nitrogen	Protein synthesis Manufacture of chlorophyll Promotes normal plant growth	Leaves become pale green, yellow, small leaves, thin weak stem and stunted growth
phosphorus	Promote root and branch growth Protein synthesis and energy release in respiration	Poor growth of roots,leaves and branches Leaves become reddish puple
Potassium	Used during photosynthesis and protein metabolism inyounger lieves	Yellow leaves with dead spots especially at marginsand tips
Calcium	Promotes normal plant growth and cell wall formation	Poor root growth Death of growing regions
Magnesium	Manufacture chlorophyll	Yellowing of leaves
Sulphur	Protein synthesis	Stunted growth Yellow patchers on leaves

Photosynthesis

The Concept of Photosynthesis

Explain the concept of photosynthesis

Photosynthesis is the process where by green plants manufacture their own food byusing light energy produced from the sun. photosynthesis takes place in plantsespecially in leaves so as to make their own food by the presence of different factors.

FACTORS FOR PHOTOSYNTHESIS

Chlorophyll, corbondioxide, sunlight energy, mineral salts, temperature and water. Equation for photosynthesis:

The Structure of the Leaf in Relation to Photosynthesis

Describe the structure of the leaf in relation to photosynthesis

The petiole or leaf stalk attaches the leaf to the branch or stem. It keeps the lamina inposition that will enable it to get a maximum amount of sunlight.

The lamina has alarge surface area, thus maximizes the absorption of light energy and carbondioxide.The lamina is also thin so that carbondioxide and light energy diffuse over a shotdistance to reach cells.

The mid rib and veins contain xylem and phloem. Xylem vessels transport water andmineral salt to the leaf. Phloem vessels transport manufactured food to other parts ofthe plant.

The Process of Photosynthesis

Explain the process of photosynthesis

It takes place inside the cell organelles known as chloroplasts.

Photosynthesis takesplace in two stages the light stage and the dark stage.

The Importance of Photosynthesis in the Real Life Situation

Outline the importance of photosynthesis in the real life situation

Importance of photosynthesis in daily life:

All organisms which are heterotrophy depend on autotrophy as source offood.
Living organisms depend on oxygen for their aerobic respiration producedduring photosynthesis
. Photosynthesis convert light energy into chemical energy which is used byother organisms
. Humans depend on photosynthesis for the energy containing fossil fuelwhich have developed over a millions of year.

Properties of Food Substance

The Basic Food Substances and Their Properties

Mention the basic food substances and their properties

Basic food substances:

Carbohydrates
Protein
Lipids

CARBOHYDRATES

Is the kind of food substance nutrients made up of carbon, hydrogen, and oxygen. Example: cassava, maize, rice etc.

TYPES OF CARBOHYDRATES

Monosaccharide
Disaccharide
Polysaccharide

MONOSACCHARIDE:

Monosaccharide is also known as simple sugar. They include glucose, fructose andgalactors.

These sugars dissolve in water and form sweet solutions.

Monosaccharideare reduced sugar. The general formulae for monosaccharide is (CH2O)n Where “n” represents a number of carbon atoms and have a value between 3 & 6.Example the formulae of glucose is (C6H12O6)

Disaccharides:

This is the kind of carbohydrate which is formed when two monosaccharidemolecules combine.

Two glucose molecules combine to form maltose.(C6H12O6) + (C6H12O6) condensation – C12H22O11+ H2Osome disaccharide are reducing sugars example lactose and maltose , other are nonreducing sugar example sucrose

Polysaccharides:

Is the type of carbohydrates formed by condensation involving severalmonosaccharideExample starch, chitin etc

Properties of polysaccharides:

They are not soluble in water
They are non reducing sugar
. They are not sweet

When put in water they form suspension

Common Reagents and Chemicals used to Determine Food Properties

Identify common reagents and chemicals used to determine food Properties

TEST FOR CARBOHYDRATES

PROCEDURE	OBSERVATION	CONCLUSION
Dissolve the food sample in water Add an equal amount of Benedict solution to the solution	 Food sample dissolveColor change from blue to green to orange,yellow and finally brick red	Reducing sugar is present
Dissolve the food sample in water to getsolution Put 2 cm of a solution obtained in a test tube Add 1 cm of HCL acid	 FIZZING COLORCHANGE FROM BLUE,GREEN,YELLOW,orange and finally brick red	Non reducing sugar is present
Boil the mixture Allow the mixture to cool Add small amount of sodium hydroxide,shake the test tube after every additional continue until fizzing stops Add 2 cm of Benedict solution then boil the mixture	 FizzingColor change from blue, green to yellow to orange and finally brick red	Non reducing sugar is present
TEST B FOR STARCH Add small amount of food sample solution in a test food.Add few drops (2-3)of iodine solution in the food sample	Color change from blue to black	Starch is present

Food Tests for Reducing Sugars, Non Reducing Sugars, Starch, Proteins and Lipids (Fats and Oil)

Carryout food tests for reducing sugars, non reducing sugars, starch, proteins and lipids (Fats and Oil)

PROTEINS

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