Biology Form Two Notes – Nutrition

These Biology Form Two notes cover Nutrition. The material is organised in clear sections for easier reading, understanding and revision.

Topic Two

NUTRITION

Concepts of Nutrition and food Nutrients INTRODUCTION 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 of plant 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 simple inorganic 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

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.

OR

Are several types of food substances that are needed by the human body for its proper

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 the body. 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-soluble vitamins are Vitamins A, O, E and K

Water-Soluble Vitamins are not stored in the body.

soluble. Vitamin B is of various forms, namely Vitamin B1, B2, B6 and B12

Vitamins B and C are water

Sources, Functions And Signs Of Vitamin

Deficiencies

Source

Liver, Milk Carrots,Orange and Yellow itamin A(Retinol) Vegetables

Lean meatjliver, eggs,tomatoes, yeast

extract sand brown rice

Liver, meat, wholegrain cereals, yeast itamin B2(Riboflavin) extracts:

itamin Meat,vegetables,yeast _extracts,whole

B6(Pyridoxine) grain cereals

itamin Fish, meat eggs, milk and liver B12(Cyanocobalamin)

(Ascorbic — Pawpaw, Citrus fruits,Fresh

Green, vegetables,tomatoes and potatoes

Function

Essential for the formation of membranes of the eyes and

the respiratory tract

Carbohydrates metabolism of all foods and release of energy

to cells

Needed for metabolism of all foods and release energy to

cells

Essential in protein

metabolism

Builds genetic materials, help to form red blood cells

• – Increaseresistant to
• diseases. Improve absorption
• of iron.- Used _insynthesis
• ofcollagen in thebones and

gums

SIGN DEFICIENCY

– Night blindness- Increased risk of

infections

– Beriberi- Loss of Appetite. – Muscle

cramps- Heart failure

– Cracks and sores around the mouth and nose- Visual

problems

– Nerve irritability- Sores in the mouth

and eyes- Anaemia

– Anaemia- Nerve

damage- Weight Loss

~ Rickets in children-

Helps to build and maintain

‘itamin D(Calciterol) Egg yolk,milk, oilfish andliver

teeth and bones

Osteoporosis (soft

bones) in adults

– Antioxidant- — –

Sunflower oil, butter,brown rice and

itamin E(Tocopherol) Preventsdamage

ERAL

peanuts cellmembrane

of — abnormalities- Infertility in rats

Defective blood

Needed for normalblood

Green vegetables and liver clotting

Minerals

coagulation resulting

in excessive bleeding

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

relatively large quantities and therefore called macro mineral sand 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

Source Function

Milk,Cheeseeges and green – Helps build strong bones and teeth- vegetables Important in clotting of blood

– Builds bones and teeth- Helps in Meat, Milk,Fish, Eggs and nuts muscle and nerve activity

Peanuts,bananas,orange juice and ; Needed for nerve and muscle function green beans

Sign Of Deficiency

– Weak bones- Bleeding easily

~ Poor bone and teeth formation

– Poor muscle contraction

Janganese

Liver,kidney,beans and

vegetables Meat, yeast

Table salt

Table salt

Spinach,pumpkin seeds, black beans

Meat, fish and liver

Kidneys,liver, tea,coffee, nuts and

fruits

lodized table salt and sea food

Roughage

Essential for making hemoglobin

Helps to heal wounds

– For nerve and muscle activity

Formation of hydrochloric acid in the

stomach

– Relaxation of ne and muscles-

Strengthening of bones

Activation of enzyme

Formation of bones

Production of thyroid hormones which

regulate growth

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

Sources Of Roughage

– Skin problems

= Muscle cramps

– Poor digestion of protein

¢ weakness- Irregular heartbeat- Weak bones Bone and

– Anemia- joint

problems

– Nausea- Dizziness- Loss of

hearing

– Goitre (enlarged thyroid gland)

Foods such as fruits, beans, cabbage, spinach, cassava, and whole baked potatoes are good

sources of roughage.

Functions Of Roughage

It helps in the passage of food and feces through the gut by aiding contraction 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

A balanced diet refers to food containing all types of food nutrients in the correct proportions. We should eat a diet low in fats, sugars and salts but high in protein, carbohydrates, vitamins,

minerals and roughage. More importantly we should take in large amounts of water. IMPORTANCE OF A BALANCED DIET

In order for the body to function properly, different food substances are required to 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

The following are nutritional requirements: Expectants: There diet should contain more protein and minerals (Calcium (Ca) and Iron (Fe))

. Lactating Mothers: Their requirements are like those of expectant but in 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

Malnutrition

This is the condition, which occurs when one fails to feed on a balanced diet. It may be too little or eating only one type. These deficiencies and disorders include 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

CAUSE, SYMPTOMS AND PREVENTION OF NUTRITIONAL DEFICIENCIES AND

DISORDERS IN HUMAN BEINGS

Disease Causes

Shortage of protein in Kwashiorkor diet

• – Lack of and equate
• amount of —_food-
• Marasmus
• Ignorance of balanced

diet preparation of food,

Effects

• – Poor growth- Diarrhea-
• Loss of appetite- Pale skin-
• Dry skin- Change colour
• and texture- Body becomes
• weak and stomach

protrudes

• – Weight loss- Slowed
• growth-Decrease dactivity-
• Lac k of energy – Shrunk
• enbuttocks

Symptoms

– Consumption

offoods

protein

rich

Prevention

– Getting adequate amounts of food – Balanced diet

Rickets

food hygiene

– Bow legs- Knock —- Provide food rich knees- An odd with vitamin

Lack of vitamin D,Phosphates and

shaped skul- D,Phosphates and Calcium

Deformed spine Calcium

– Pain in joints- – Provide diet which Lack of vitamin C Stunted growth- _containsfruits- Avoid Bleed in gums prolonged cooking

– Swelling of the — – Provide iodized salt thyroid gland and water(H20)

Lack of iodine Digestive System in Human DIGESTIVE SYSTEM IN HUMAN BEINGS,

The digestive system of human refers to the human alimentary canal and the organs 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, esophagus, stomach, small intestine, (duodenum and 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 of bacteria 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 for absorption

The Digestion Process in Human Being

Digestion Process In Human Beings

Digestion is the process by which food is broken down into a form that can be absorbed and used

by the body.

Digestion process involves two processes, which are mechanical break down of food and chemical break down of food. The mechanical break down of food takes place in the mouth

where the food is chewed by teeth so as to reduce it into small pieces.

Digestive enzymes achieve chemical break down of food. The digested food is absorbed and

assimilated in the body.

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

presence of food in the mouth stimulates the salivary gland to 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 medium for amylase enzyme

Difference Between the Human Digestive System with that of Other

Mammals

The ruminants’ digestive system differs from human digestive system in the following 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

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 bacteria destroy 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 stomach wall due

to enzyme reactions.

Constipation Refers to the decrease in frequency of formation of stool. It occurs when the stool

becomes dry and hard due to excessive water absorption in the colon

FlatulenceThis 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

element Role

Protein synthesis Manufacture of chlorophyll Promotes Leaves become pale green, yellow, small leaves, thi nitrogen . normal plant growth weak stem and stunted growth

phosphorus Promote root and branch growth Protein synthesis and Poor growth of roots, leaves and branches Leave|

energy release in respiration become reddish purple

p Used during photosynthesis and protein metabolism in Yellow leaves with dead spots especially at margin] otassium younger lieves and 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

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

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

The Concept of Photosynthesis

Photosynthesis is the process where by green plants manufacture their own food by using light energy produced from the sun, Photosynthesis takes place in plants especially in leaves so as to

make their own food by the presence of different factors. FACTORS FOR PHOTOSYNTHESIS

Chlorophyll, carbondioxide, 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 in position that will enable it to get a maximum amount of sunlight. The lamina has a large 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 shot distance to reach cells.

The mid rib and veins contain xylem and phloem. Xylem vessels transport water and mineral salt

to the leaf. Phloem vessels transport manufactured food to other parts of the plant.

The Process of Photosynthesis

It takes place inside the cell organelles known as chloroplasts. Photosynthesis takes place in two

stages the light stage and the dark stage.

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 of food. Living organisms depend on oxygen for their aerobic respiration produced during photosynthesis Photosynthesis convert light energy into chemical energy which is used by other organisms

. Humans depend on photosynthesis for the energy containing fossil fuel which have developed

over a millions of year.

Properties of Food Substance

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:

‘a, maize, rice etc

Types Of Carbohydrates

– Monosaccharide

Disaccharide

Polysaccharide MONOSACCHARIDE:

haride is also known as simple sugar. They include glucose, fructose and galactose. These sugars dissolve in water and form sweet solutions. Monosaccharide are reduced sugar. The

general formulae for monosaccharide is (CH2O)n

Where “n” represents a number of carbon atoms and have a value between 3 and 6. Example the

formulae of glucose is (CeHi20¢) DISACCHARIDE:

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

Two glucose molecules combine to form maltose. (CsHi204) + (CéHi204) condensation =

Ci2H22011+ H:O some disaccharide are reducing sugars example lactose and maltose , other are

non reducing sugar example sucrose POLYSACCHARIDE:

Is the type of carbohydrates formed by condensation involving several monosaccharide Example

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

Observation Conclusion

• Food sample dissolve
• issolve the food sample in water Add an equal amount of Reducing sugar i
• Color change from blue to green to
• Benedict solution to the solution present
• orange, yellow and finally brick red

FIZZING

issolve the food sample in water to get solution Put 2m of a COLOR CHANGE FROM BLUE, Non reducing suga

kolution obtained in a test tube Add 1 cm of HCL acid GREEN, YELLOW, orange and is present finally brick red

Boil the mixture Allow the mixture to cool Add small amount of — Fizzing odium hydroxide, shake the test tube after every additional Color change from blue, green to Non reducing sugat continue until fizzing stops Add 2 cm of Benedict solution then yellow to orange and finally brick _ is present

oil the mixture red

TEST B FOR STARCH Add small amount of food sample lution in a test food. Add few drops (2-3)of iodine solution in the — Color change from blue to black Starch is present

food sample

Test For Carbohydrates

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 it edible,

• 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 cheers from 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

refrigeration. Irradiation which is by using radiations such as gamma rays to kill micro organisms

Eliminating the moisture that is needed for growth of micro organism for instance by drying,

salting, smoking ete . Adding chemicals such as salt sugar, carbon monoxide to prevent physical changes in food FOOD STORAGE

Refers to the methods used to keep or reserve of food for future use. Food storage can be done on a small scale at the family level for example in a family granary or food store. Or large scale for

large populations e.g in government stores of grains

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

They are two methods of food processing and preservation which are; traditional methods

modern methods

Traditional Methods

These are methods used to process and preserve food which doesn’t require the use of

technology.

These are methods used to process and preserve food which doesn’t require the use of

technology. The following are the traditional ways. CURING

It involves additional of substances such as salt, sugar, spaces and vinegar to animal foods, moist meat and fish. Curing removes water making it unavailable for the growth of microorganism it

also improve the taste of food. Sausages, be con 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 moisture content. Reducing the amount of water in food discourages the growth of microorganisms. Some food such as banana and

cassava are cut into small pieces to fasten the process. SMOKING

Smoking is the traditional method which is used to reduce moisture content of food to prevent

growth of microorganisms. Grains, meat, fish can be dried slowly 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 can be 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 cost slow

. 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.

MODERN METHODS OF FOOD PROCESSING AND

PRESERVATION

Refrigeration And Freezing

Is the temporary storage of food at low temperature of up to 4 centigrade in order to slow down the growth of microorganisms. Freezing involves storing food 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 and butter. Freezing is mostly used for

meat, fish, fruits and vegetables. PASTEURIZATION

Thus method of preservation was named after its inventor Louis Pasteur. It involved heating food to a very highest temperature for a short time in order to kill the micro organisms that can cause spoilage. Pasteurization maintains the nutrients content and flavor of food. Examples of food that

can be pasteurized are milk and fruity juice. CANNING AND BOTTLING

In this method, food is preserved by heating it in airtight vacuum, sealed bottles or cans. The container is filled with food then the air is pumped out to form a vacuum. The container is sealed and heated to kill microorganisms and enzymes but not enough to overcook the food. Food that can be bottled or canned include tomatoes, fruits, juice, beef, fish and packed beans. Bottled or

canned food can be kept for months or even years. USING ADDITIVES

This method involved the use of chemicals such as sodium benzoate, sodium chloride, 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. After drying the food is then

sealed in moisture proof containers.

Irradiation

Is the modern method which involve the use of rays of energy to stop the growth of microorganisms in stored food. Example in onions, beans and potatoes. This makes food last

longer. It also prevents sprouting in onions and potatoes.

Advantages Of Modern Methods.

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 offood DISADVANTAGES OF MODERN METHODS

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 OF FOOD

PROCESSING AND PRESERVATION

Traditional Methods Modern Methods

Les tiful High costiful

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 __It uses chemicals to process and preserve foodlt is used]fpy

most people few people

It select type of food to be processed and preserved Itis not selective