Topic 2: Nutrition – Biology Notes Form 2
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.
OR
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
-
Sedentaryworkers: These are individuals who stay in one place for along timewhile performing their daily occupational activities. Due to theirlifestyle and occupation,obesity is increasingly common among them, theylimit their intake of food rich in lipids.
-
Sick people: Theyneed special and plenty of nutrients to help recover their health, thosewho have incurable diseases such as HIV/AIDS should get food that willhelp them to manage their conditions. They need totake plenty of fruitsand 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 cariesThis is commonly referred to as tooth decay. It occurs when bacteriadestroy the outer part of the tooth.
Heart burnRefers
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 ulcersRefers to the sore in stomach lining. It is caused by erosion of stomachwall due to enzyme reactions.
ConstipationRefers
to the decrease in frequency of formation of stool. It occurswhen the
stool becomes dry and hard due to excessive waterabsorption 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.
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:
- i. 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 dissolveColor 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 |
FizzingColor 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
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.
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 offood.
DISADVANTAGES;
- The chemicals used can be harmful if eaten in excess
-
Theseadvanced technology involve means where they are used only in certainareas 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 |
