FORM 2 BIOLOGY STUDY NOTES, TOPIC 2: NUTRITION

 

Topic 2 - NUTRITION

 

TOPIC 2: NUTRITION

 

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 of plant and animal body.

 

The Concepts of Nutrition and Food Nutrients

FUNCTION OF FOOD

(i)       Oxidized to release energy

(ii)     Used in growth of cells

(iii)    Used to repair lost cells and tissue

 

TYPES OF NUTRITION

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

a)   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)

b)   Heterotrophic Nutrition

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

 

The Importance of Nutrition in Living Things

(i)       Prevent diseases

(ii)     Helps growth and development of cells, tissue and organs

(iii)    It helps to repair damaged parts

(iv)   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

1. 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

(i)    It is used in body building

(ii)  Used by body for tissue growth and repair such as healing of wounds and replacement of skin

(iii) Used as a source of energy, especially when the body lacks carbohydrates and lipids

(iv)It enables red blood cells to transport oxygen in our bodies

 

2. 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

(i)       They are chief source of energy

(ii)     In plants they are stored as starch

(iii)    In animals they are stored as glycogen

 

3. 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

(i)       Lipids are used as a source of energy

(ii)     Protect the organs such as heart and kidneys

 

4.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. 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.

 

5. Minerals

- 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

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)

 

5. 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 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

 

6. WATER

-    This is a compound containing element hydrogen and oxygen

Sources Of Water

-    Rainfall, Rivers, Springs etc.

Functions Of Water

(i)       Used in digestion of food

(ii)     Used in transport of material in the body

(iii)    Used as solvent in chemical reaction

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 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:

(i)       Carbohydrates provide energy

(ii)     Vitamins needed to keep the body healthy

(iii)    Minerals are needed for protection against diseases

(iv)   Water is a universal solvent

 

NUTRITIONAL REQUIREMENTS FOR DIFFERENT GROUPS OF PEOPLE

The following nutritional requirement

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

(ii)     Lactating Mothers: Their requirements are like those of expectants but in greater amount to feed the body

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

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

(v)     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.

(vi)   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

 

Nutritional Deficiencies And Disorders

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

Causes of Malnutrition

There three cause of mulnutrition

(i)          Eating too little

(ii)        Eating too much

(iii)       Eating one type of food

(iv)      Effects of Malnutrition

(v)        Excessive feeding causes obesity

(vi)      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

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

 

The Main Parts Of Alimentary Canal

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

Adaptations Of Stomach To Its Mode Of Function

(i)          Stomach has sphincter muscles to prevent food from flowing back into the oesophagus

(ii)        Stomach has gastric glands, which produce gastric juice for the digestive process.

(iii)       Also in the stomach of a young baby there is renin which coagulates milk

(iv)      Stomachs have mucus which protects it from corrosion by digestive enzymes

(v)        There is hydrochloric acid for the emulsification of fats and killing of bacteria

 

Adaptations Of Illeum To Its Functions

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

(ii)        It has secretory glands, which produce digestive enzymes

(iii)       It is connected to the liver by the bile duct which enable the bile to reach ileum

(iv)      It has finger like projections called villi for the absorption of food

(v)        The ileum is very long to ensure sufficient absorptions of food

(vi)      The villi have large network of blood capillaries for transporting absorbed food to all parts of the body

(vii)     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

(i)       Have salivary amylase enzyme that converts starch into maltose

(ii)     To moisten the food

(iii)    To provide medium for enzyme reactions

(iv)   Have mucus to lubricate food for easy swallowing

(v)     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

 

Differences Between Human Digestive System And Ruminants’digestive System

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

(i)       Ruminants have more elaborate system to enable cellulose digestion

(ii)     The stomach of ruminants have four chambers (rumen, reticulum,omasum, abomasum)

(iii)    The food is regurgitated, chewed, and again then passed to omasum.

 

Common Disorders and Diseases of the Human 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.

(i)       Dental caries This is commonly referred to as tooth decay. It occurs when bacteria destroy the outer part of the tooth.

(ii)     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.

(iii)    Stomach ulcers Refers to the sore in stomach lining. It is caused by erosion of stomach wall due to enzyme reactions.

(iv)   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.

(v)     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

 

Symptoms Of Dental Caries

(i)    Tooth ache

(ii)  Holes in the teeth

 

Control Measures To Caries

(i)       Regular brushing of teeth

(ii)     Damaged teeth can be filled with artificial crown

(iii)    Minimization of intake of foods rich in sugar

(iv)   Avoid eating very hot or cold foods

(v)     Have regular dental check ups

 

Symptoms Of Stomach Ulcers

(i)          Burning pain in the stomach

(ii)        Nausea and vomiting

(iii)       Tiredness and weakness

(iv)      Blood in vomit or stool

 

Control Measures To Stomach Ulcers

(i)          Medication

(ii)        Avoid smoking

(iii)       Avoid taking alcohol

(iv)      Avoid eating acidic foods

 

Symptoms Of Constipation

(i)       Lack of bowel movements for two or three days

(ii)     Hard stools

(iii)    The urge to go for long call even after you have just been to the toilet

 

Prevention Of Constipation

(i)       Eat enough fibre

(ii)     Drink enough water

(iii)    Exercise regularly

(iv)   Seek medical help

 

Causes Of Flatulence

(i)       Swallowed air

(ii)     Eating food that causes gas such as beans, cabbage, milk and onions

(iii)    Poor absorptions of carbohydrates

 

Symptoms Of Flatulence

(i)       Abdominal pain

(ii)     The constant urge to pass wind

(iii)    Excessive belching

(iv)   Accumulation of gas in the stomach

 

Prevention Of Flatulence

(i)       Avoid foods that produce gas

(ii)     Chewing food properly

(iii)    Limit the amount of food which are

 

 

 

NUTRITION IN PLANT, MINERAL REQUIREMENT IN PLANTS

 

Essential Mineral Element in Plant Nutrition

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

(i)       Micro nutrients or minerals

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

(ii)     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.

 

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 purple
Potassium	Used during photosynthesis and protein metabolism in younger lieves	Yellow leaves with dead spots especially at margins 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

 

 

Photosynthesis

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

 

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:

(i)       All organisms which are heterotrophy depend on autotrophy as source of food.

(ii)     Living organisms depend on oxygen for their aerobic respiration produced during photosynthesis

(iii)    Photosynthesis convert light energy into chemical energy which is used by other organisms

(iv)   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:

(i)       Carbohydrates

(ii)     Protein

(iii)    Lipids

 

1.  CARBOHYDRATES

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

 

Types Of Carbohydrates

(i)       Monosaccharide

(ii)     Disaccharide

(iii)    Polysaccharide

(i)      Monosaccharide:

Monosaccharide is also known as simple sugar. They include glucose, fructose and galactors. 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& 6. Example the formulae of glucose is (C₆H₁₂O₆)

(ii)     Disaccharides:

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

Two glucose molecules combine to form maltose. (C₆H₁₂O₆) + (C₆H₁₂O₆) condensation = C₁₂H₂₂O₁₁+ H₂O some disaccharide are reducing sugars example lactose and maltose , other are non reducing sugar example sucrose

(iii)    Polysaccharides:

Is the type of carbohydrates formed by condensation involving several monosaccharide Example starch, chitin etc

Properties of polysaccharides:

(i)       They are not soluble in water

(ii)     They are non reducing sugar

(iii)    They are not sweet

(iv)   When put in water they form suspension

 

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 get solution Put 2 cm of a solution obtained in a test tube Add 1 cm of HCL acid	§  FIZZING §  COLOR CHANGE 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 Processing, Preservation and Storage

 

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;

(i)          Picking, sorting and washing fruits and vegetables

(ii)        Cooking by boiling steaming, roasting backing or frying

(iii)       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

(i)       Keeping out micro organisms for example by canning or bottling

(ii)     Using high temperature to kill microorganisms that cause spoilage eg.By pasturalization and boiling

(iii)    Using very low temperature to slow down the growth of microorganisms for example refrigeration.

(iv)   Irradiation which is by using radiations such as gamma rays to kill micro organisms

(v)     Eliminating the moisture that is needed for growth of micro organism for instance by drying, salting, smoking etc

(vi)   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. 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

(i)       prevents wastage of food

(ii)     it saves money by preventing spoilage of food

(iii)    maintains the quality of food

(iv)   prevents the growth of micro organisms that can cause illness

(v)     improve the flavor of food

(vi)   removes armful toxins and micro organisms from food

(vii)  makes food available even where they are not in season

(viii)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;

(i)       traditional methods

(ii)     modern methods

 

(i)      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.

(ii)       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.

(iii)     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.

(iv)      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

(v)        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.

(vi)      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 And Preservation And Storage

(i)       They are simple and they can be done by most people

(ii)     They use locally available materials and simple technology thus keeping cost slow

(iii)    No harmful chemicals are added to the food

(iv)   Curing and smoking add distinct flavor.

(v)     Most methods do not destroy nutrients

 

Disadvantages:

(i)       Food can be preserved and stored for the limited period of time

(ii)     They are manual and thus difficult to apply on a large scale

(iii)    Traditional methods are highly limited in the variety of food that can beprocessed preserved and stored.

Modern Methods Of Food Processing And Preservation

2.    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.

3.    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.

4.    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.

5.    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

6.    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.

7.    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 Moderm Mothods

(i)       Food can last for many months and even a year

(ii)     Modern methods can process, preserve, and store large variety of food.

(iii)    They are advanced technology bused in fast and can handle huge quantities offood.

Disadvantages;

(i)       The chemicals used can be harmful if eaten in excess

(ii)     These advanced technology involve means where they are used only in certain areas for instance refrigeration requires electricity.

(iii)    The process used for example canning and pasteurizing require special skills.

(iv)   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