FOOD HYGIENE

FOOD HYGIENE

Means practices that safeguard against food contamination that may lead to food poisoning and spoilage.  Proper personal and kitchen hygiene practices ensure food remains wholesome and safe.

NB:- favourable conditions for growth of micro-organisms are warmth, moisture, darkness and dirt.

Kitchen hygiene

  • Kitchen hygiene is cleanliness of surfaces, equipment and proper disposal of refuse,
  • Food storage, production, service handling and preparation should be carried out in a hygienic manner to prevent food contamination, – hygiene practices include:
  • keeping kitchen free from spilt food, crumbs and scraps, that attract flies, cockroaches and rats,
  • cleaning cooking and serving utensils properly after use and drying before storeage,
  • kitchen clothes to be washed daily and boiled to kill germs and if white should be bleached once in a while to remove discolouration,
  • work surfaces to be cleaned with warm water and detergent,
  • lining kitchen refuse bin before use,
  • food storage equipment to be clean at all times e.g refrigerator, kitchen stores, vegetable racks and meat safes.
  • Store to be checked often and any food/vegetable showing signs of spoilage to be removed and discarded,
  • practicing principles of first in first out (fifo) to be practiced when storing foods to prevent food spoilage,
  • kitchen floor to be swept of any spilt food and vegetable peelings, wipe grease from floors they may cause falls, sprains and fractures, floors to be kept clean because they attract flies.
  • providing adequate lighting food to be cooked and stored in clean and well ventilated cupboards or larders and free from pests e.g flies, rats, cockroaches/even pests,
  • not handling cooked food with bare hands instead use properly cleaned kitchen tools,not storing cooked food for too long under warm conditions to avoid food poisoning, leftovers to be cooked and stored appropriately in small portions and shouldn’t be reheated more than once,
  • clean water to be used for preparing food and all kitchen equipment to be cleaned before use,
  • containers used to hold food to be free from cracks and chips,
  • wasting foods to be eaten raw e.g fruits and vegetables to be washed thoroughly under clean water.

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Persons handling food to observe the following

  • wear protective clothing to prevent contaminants from outdoor clothing coming into contact with food, surfaces and equipment:

NB: hair to be covered and kitchen shoes to be worn,

  • hands to be washed with a soft scrubbing brush in warm soapy water and dried with a towel, should be washed thoroughly after visiting toilet, handling food refuse, handling money, touching parts of the body
  • avoid wearing jewellery, rings, watches and bracelets they trap grease, dirt and              bacteria.
  • avoid smoking, tasting food using fingers/other activities that are bad,
  • persons suffering from infectious diseases e.g diarhoea, typhoid, cholera, and dysentery and other diseases e.g sore throat, skin infections, worms, hepatitis should not handle food.

Food spoilage and poisoning

Food spoilage

It is deterioration of food resulting in food becoming unfit for human consumption.

Causes of food spoilage

(i) aerobic,

(ii)anaerobic

(i) Aerobic

Aerobic is caused by micro-organisms in presence of oxygen, e.g moulding of bread and rotting of meat.

Anaerobic occurs within the interior of food parts in sealed containers where oxygen is absent or present in limited quantities e.g in canned foods.

Causes of food spoilage

  • oxidation of chemicals present in fats or fatty foods,
  • chemical present in pesticides and herbicides sprayed on fruits and vegetables,
  • chemicals present in food containers wrapping and packets,
  • action of enzymes in fruits making them overripe,
  • reactivity i.e decomposition of fats,

Food poisoning 

  • some micro-organisms produce toxins which are harmful to human beings,
  • contaminated food may lead to food poisoning, it is considered an illness due to consumption of food containing toxins, chemical poisons or harmful micro-organisms.

Causes

insecticides, pesticides, herbicides, kerosene, detergents and dry cleaning agents can contaminate food and cause food poisoning,

  • bacterial contamination: caused by bacteria that get into the food and contaminate it. The bacteria enters the alimentary canal and produces toxins that cause abdominal pains and vomiting. foods like ice cream, nuts, meat pies and poorly stored cooked foods provide conditions for growth of bacteria.
  • Natural poisoning occurs in badly stored grains, e.g stored in damp conditions and when not completely dry, they produce poisons called aflatoxins. Aflatoxins are poisonous substances that are produced by a mould fungus,  to prevent it plants should be stored only when completely dry;

NB: poisonous parts of certain plant food e.g cassavas can also cause food poisoning.

Signs and symptoms of food poisoning i) vomiting ii) severe stomachache/abdominal pains, iii) diarhoea,

  1. fever,
  2. general body weakness,

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Prevention of food spoilage and poisoning

  • avoid buying canned foods that have expired, check expiry dates always,
  • buy fruits in seasons,
  • buy from clean market and vendors,
  • store under right conditions to avoid spoilage,
  • storage facilities to provide adequate space with protection against dust, insects and rodents,
  • avoid storing near foods to prevent chemical contamination, poisons and toxins,
  • place refuse in correct and sealed containers away from food area,
  • foods to be eaten e.g fruits and veges to be washed under clean running water,
  • frozen foods to be thawed completely before cooking, it ensures heat penetrates food adequately and kills harmful bacteria,
  • leftovers to be cooled completely and be stored under low temperatures and be packed in small portions, avoid reheating more than once,

Storage of perishable and non-perishable (dry) foods

Perishable foods

Examples – meat, meat products, vegetables, milk, milk products and eggs.

  • They deteriorate very first, they have to be stored at low temperature to maintain freshness,

Storage:

  • Raw foods e.g meat and poultry not to be used immediately should be divided into portions, labelled and stored in the freezer,
  • All stored foods to be covered,
  • Meats, e.g beef, bacon, pork, poultry and fish to be used within 2 days, should be stored on first and second shelves, directly under freezer,
  • Butter and cheese to be wrapped in greaseproof paper and to be stored on top shelf/on special compartments on door,
  • Caned meat and other cooked foods to be stored in the middle shelf,
  • Foods likely to deteriorate faster should be kept on shelf closest to freezer compartment.
  • Vegetables, salad ingredients and nitrous fruits to be wrapped in perforated polythene bags and to be stored in the crisper,
  • Bananas shouldn’t be stored in a fridge they turn black,
  • Eggs to be on egg racks on door, shouldn’t be washed because it makes them porous shell susceptible to entry of bacteria,
  • Milk to be in bottles in correct rack on the door

Storage of non-perishable (dry) foods

  • Should be stored in a cupboard/food store or ladder,
  • Food to be stored in the larder are tea leaves, coffee, sugar salt, jam, and cooking fat,
  • should be packed in dry covered containers (plastic) if not already in containers and clearly labelled.

Other methods of storing foodstuffs at home

  • milk can be put in a clean bottle (jug) with a lid and stored in s container of cold water,
  • a muslin cloth is then put over bottle with ends touching the water to keep the surrounding cool,
  • water moves up cloth by capillary action and draws heat from milk,
  • as it evaporates, heat is lost through cooling milk,
  • it can keep fresh for 12 hours.

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Water treatment at home

Water needs to be purified because or presence of micro-organism e.g bacteria cause water borne diseases e.g typhoid, dysentery and cholera.

Methods of purifying water

  1. Sedimentation
  • water is collected in a container and left to stand for a while, solid particles e.g leaves and soil will settle at the bottom,
  • to quicken the process salts of aluminium can be added especially to hard water, solids in the water will coagulate and sinks to bottom,
  • the water may still contain bacteria in so should be boiled before drinking.
  1. Filtration

After sedimentation the water may still be brown so it is passed through a series of filter beds having different grades of sand and gravel.

Diagram

all minute impurities are removed and water starts to sparkle, home made filters are useful in areas where water is fetched directly from rivers, dams or lakes,  a low concentration of chlorine or ozone is added to kill micro-organisms.

  1. Boiling
  • it kills disease causing micro-organisms and other parasites,
  • filter water using a clean cloth,
  • put in a container heat and bring to boil approximately 10 minutes to ensure all micro-organisms and parasites are killed,
  • cool covered,
  • store in some container,
  • if it is transferred to another container the container should be rinsed in boiled water,

Storage;

  • purified water should be stored in a sterile container to prevent contamination.

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METHODS OF COOKING

Reasons for cooking food

  • to improve appearance of food, make food attractive,
  • to improve flavour or taste of food,
  • to make food tender and easy to chew,
  • to kill germs and parasites,
  •  to keep food for long, e.g
  1. Boiling ii. Stewing iii. Roasting iv. Baking v. Frying
  2. Steaming

Factors that determine methods of cooking

  • Types of food,
  • The health condition of consumer of meal,
  • The available time, iv. The available fuel,
  • The available cooking equipment.

Categories of cooking methods

  1. moist heat methods e.g boiling, steaming and stewing,
  2. dry methods e.g baking, roasting and frying
  3. Moist heat methods of cooking
  4. Boiling

Boiling

It is cooking food completely immersed in liquid bubbling at 100oC and keeping it at that temperature till ready.

Suitable foods;

  • meat
  • poultry
  • root tubers e.g arrow roots, yams and sweet potatoes

Rules for boiling foods:

  • boil in just enough water and nearer serving time to preserve nutrients,
  • pan should be covered,
  • green veges to be boiled in salted water to retain colour,
  • root veges to be cut into even sized pieces and be put in water before boiling,
  • meat to be cut into large pieces and put in boiling water to be to seal the inside for juices to be retained,
  • once food boils to boiling point heat should be simmered,
  • foods should not be overcooked, retain shape, nutrients, cocoon and flavour,
  • liquid for boiling meat and veges to make stock/sauces,
  • seasoning to be added to boiling water,

Advantages of boiling

  • needs little attention,
  • liquid for boiling can be used to prepare stock, sauces and gravies,
  • convenient if modern type of cooking equipment are not available,

Disadvantages 

  • flavour and nutritive value damaged.
  1. Stewing

it is cooking food in a measured amount of liquid and then allowed to simmer,

Suitable for;

  • beef,
  • poultry,
  • vegetables
  • fruits
  • aim is to give food enough time to soften and to retain nutrients and flavour.

Rules

  • meat should be cut into neat and equal pieces to cook evenly,
  • stewed beef and poultry to be browned well before adding liquid to seal juices,
  • enough liquid, stock or water to be added to avoid having thin watery stew,
  • pan/pot to be covered with a fitting lid,
  • use gently heat during cooking to avoid hardening of proteins and damaging food texture and flavour,
  • check on seasoning before serving,
  • serve in liquid used for cooking,

Advantages

  • an economical method of cooking cheap cuts of meat,
  • needs little attention,
  • can be on top of stove in oven, – good for cooking tough cuts of meat, – nutrients not lost.

Disadvantages

  • slow method so needs adequate time,
  •   consumes a lot of fuel.

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  1. Steaming

It is cooking food using steam from boiling water,

Steam doesn’t come into direct contact with food instead comes in contact with the container holding food:

Suitable for;

  • fish fillet
  • puddings

Methods of steaming 

  • plate method,
  • bowl steaming,
  • using a steamer,
  • using a colander

Plate method:

Food in a covered plate is placed over boiling cooking pan.

NB:- root vegetables can be cooked at same time to save fuel.

  • Bowl steaming

Food is placed in a covered bowl and placed in a pan of boiling water

  • Using a colander

A colander covered is used to hold food.

It is placed on a saucepan of boiling water,

NB:- the colander should fit well on saucepan, and base shouldn’t come into contact with boiling water.

–     Using a food steamer

A steamer with several compartments for different foods is used.

Rules to follow;

  • Follow instructions if using a steamer,
  • Steam to be produced constantly so water bath should be allowed to evaporate, This will prevent pan containing water not to be damaged and food not to burn.
  • Always add into the water bath some water to maintain,
  • Cover food carefully to avoid direct contact with steam/water,
  •  Steamed/pan to have a tight fitting lid to avoid loss of steam,
  •  Direct steam away from you when opening lid to avid scalds.

Advantages of steaming foods.

  • Food is light and easy to digest so suitable for invalids and convalescents,
  • Nutrients and flavour not lost,
  • Different dishes can be cooked same time e.g food may be cooked on water being used for boiling root vegetables.

Disadvantages of steaming foods

  • Requires a lot of attention to ensure water bath does not boil, evaporate and get dry,
  • Dangerous steamer may cause scalds,
  • Not good for cooking tough foods.

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Frying

It is cooking food in a lot of fat or oil in a pan.

Methods of frying

  • shallow fat frying
  • deep fat frying
  • dry fat frying
  • Shallow frying
    1. it is cooking food in hot fat half way the food,
    2. suitable for eggs, sausages, thin slices of meat, fish, poultry joints and pan cakes.
  • Deep fat frying
    1. food is cooked in hot oil ⅔ of a pan that completely covers the food,
    2. a deep fat fryer, strong deep pan, a frying basket and draining spoon are required, suitable for potatoes chips, mandazi and samosas.
  • Dry fat frying
  1. cooking food in its own fat in a shallow pan/cooking in a lightly greased pan, – oil/fat used comes from the food being cooked, e.g bacon, and cuts of pork.

General rules for frying foods

  • prepare food correctly e.g for fish and meat cuts shouldn’t be more than 2.5cm thick to ensure thorough cooking,
  • use good quality fat that has a high smocking point to prevent food from burning on heating,
  • pan should be strong for fat not to overheat,
  • for deep frying, should be ⅔ of a pan to avoid overflowing,
  • heat fat to right temperature before putting food to prevent food from absorbing fat and becoming too greasy,
  • if fat is too hot it burns the outside of food and leaves it undercooked
  • foods to be coated unless starchy like potatoes and doughnuts,
  • use butter/beaten eggs and bread crumbs,
  • others should be dried before frying e.g potato chips, –
  • lower food gently into hot fat to avid accidents e.g scalds,
  • avoid overloading the fryer it lowers the temperature of oil,
  • avoid having boiling water near fryer because the bubbling water may get onto the frying hot oil and cause accidents,
  • drain any surplus fat/oil on absorbent paper before serving, NB: should not be prepared for weight watchers.
  1. Dry heat methods of cooking

Baking

  • it is a dry method of cooking food using dry hot air in an oven. Suitable for foods that have enough moisture e.g potatoes and flour mixtures e.g cakes, scones and bread.

Rules for baking foods

  • oven should be pre-heated to correct temperature before putting food in oven,
  • place food in the right shelf, top is hottest, middle and lower are moderately hot,
  • always observe baking time (duration so as to reduce baking temperature for some foods) e.g for yeast mixtures temperature should be reduced once yeast is leveled and crust is formed for even cooking,
  • avoid opening oven door before mixture settle because cool air can make them sink,
  • test the food for readiness before removing from oven,
  • turn the foods on a cooling tray or rack to cool unless they are to be served in the dishes in which they were baked,

Advantages

  • doesn’t require a lot of attention if temperature is well set,
  • light and easy to digest,
  • saves fuel because several dishes can be cooked at same time,

Disadvantages:

  • only suitable for certain dishes,

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Roasting 

  • as cooking food close to a source of food; suitable foods;
    1. meat
    2. maize
    3. sweet potatoes
    4. yam
    5. arrow roots
    6. fish

food can also be roasted in an oven/while rotating on a spit, fat should be used to bake foods before roasting, good for cooking meat.

Rules for roasting foods

  • foods to be prepared correctly and seasoned before putting in roasting pan,
  • joints to be raised from bottom of pan to avoid frying,
  • oven should be pre-heated to the correct temperature before putting food,
  • charcoal burners must be red hot before putting food to quickly brown the top and seal juices, it ensures food is free from smoke,
  • frequently basting and turning of food should be done to keep food moist and ensure even cooking,
  • use juices from pot roasted meat/chicken to make gravy,
  • avoid pricking the surface of meat because this allows juices to run out and leave the roasted piece dry.

Advantages of roasting foods

  • it is quick method,
  • roasted food is attractive and appetizing, – it is easily digested, – it is tasty especially meat.

Disadvantages

  • it is expensive meat to be roasted, should be of high quality,
  • needs constant attention,
  • food to be basted and turned frequently to prevent burning and drying.

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TEXTILE FIBRES

A fibre is hair like unit of raw material from which clothes are made.  A textile fibre is a unit of matter which is spun/weaved into yarn and made into fabric.

Properties of acetate rayon

  • has good lustre,
  • drapes well,
  • soft,
  • can be treated to repel water, – weaken when wet,
  • doesn’t with stand high heat,
  • has a thermoplastic nature,
  • leads can be permanently pleated,
  • less absorbent than viscose rayon so dries easily,
  • develops and holds static electricity,
  • resistant to shrinking, creasing and stretching,
  • easily damaged by chlorine, bleaches and acetone,

Uses: 

For dress materials, linings, underwears, soft furnishings, scarves and carpets,

Examples;

Crepe, ninon, taffeta, velvet, jersey, satin, net etc.

Elastic fibre

Are elastic rubber like substances e.g lycra and spandex.

Properties of elastofibres

  • excellent elasticity and recovery,
  • non resistant to heat,
  • thermoplastic,
  • good resistance to abrasion,
  • resistant to perspiration and body oils,
  • strong and durable,
  • generates static electricity,
  • absorbent,
  • cool and allows skin to breath e.g lycra and spendix.

Uses:

  • makes corcets, brassierses, bikers, swimsuits, raincoats, and support hosiery.

PHYSICAL IDENTIFICATION OF TEXTILE FIBRES i) Cotton

  • feel light,
  • burns rapidly in and out of flame,
  • wet on bright yellow flame,
  • smells like burnt paper leaving grey ashes.
  1. Linen
  •  tougher than cotton and has a luster,
  •  burns readily with a bright flame,
  • emits smell of burnt grass.

Wool

  • it feels hairy,
  • it is warm,
  • burns with spluttering noise and smoulders leaves blade ash smells of burnt feathers and hair,
  1. Silk
  • feels smooth and has lustre,
  • burns with spluttering noise and is self extinguishing,
  • smells like burnt hair/feathers.
  1. Viscose
  • viscose feels soft and smooth,
  • has appearance of alka,
  • burns readily with a bright flame leaving a grey ash, – smells like burnt paper.
  1. Acetate

melts and burns with a bright flame leaves hard brittle irregular beads,

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Nylon

repels flames and melts into a hard bead.

Polyester

  • shrinks and melts on burning ,
  • burns with difficulty smells leaving behind a hard round bead,
  1. Acrylic
  • shrinks and melts on burning into a tar like bladder bead,
  • burns with a sooty flame, leaving a hard round black bead,
  •  it is self extinguishing.

 

  1. Elastofibres

shrink and melt from flame, forming a hard irregular bead

  1. Asbestos
  • melts and forms a gummy substance called residue.

THE LARGE SEWING EQUIPMENTS

Table /worktop

  • should be large enough,
  • comfortable height for user, – smooth and flat not to spoil fabric,
  • shouldn’t be polished.

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Use and care

  • dust before using
  • avoid scratching with sharp objects e.g tracing, – avoid staining with ink/carbon.

Long mirror

  • should be large enough for one to see himself from toe during fitting,

Use and care

  • used when making fitting garments,
  • clean with a dry cloth before use, – avoid scratching,
  • should be firmly fixed.

Drawers 

  • should be large enough, – finished smoothly,

Use and care

  • for storing needlework,
  • should be lined with newspapers.

Wardrobes 

  • should be of smooth wood,
  • smooth finish,
  • lockable,
  • rod/rail should be present

use and care

  • for hanging complete/nearly complete garments,
  • clean regularly and place mothballs occasionally.

Hangers

  • should be accounted sizes,
  • should be of smooth wood, plastic/metal,
  • should be smooth,
  • should be strong with wide enough to carry work,
  • should have wounded corners to keep shape of garments.

Use and care

  • for hanging complete/nearly complete garments,
  • dust occasionally

Irons

  • non rusting materials – medium management smooth sole
  • pointed toe to reach into galtery
  • should be thermostatic (control heat automatically).

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Ironing board

Use and care

  • used to press work at every stage,
  • adjust to a comfortable height,
  • remove a wash cover regularly,
  • fold and protect from dust when not using.

 THE SEWING MACHINE

Parts of a sewing machine

The slide plate

It covers the part that houses bobbing case and protects shuttle from dust.

Shuttle (feeddog)

The loop that revolves back and forth during process of machining.

It facilitates locking of upper and bobbing thread and causes fabric to move forward.

Feedplate/throat plate

Protects shuttle and area around it.

Presser foot lifter

Holds fabric against feed dog during stitching.

Tension disc

Controls tightness of thread during stitching

Thread take up lever

Controls movement of thread and helps in sewing process.

Presser bar (screw)

Used to raise/lower presser foot, adjusts pressure exerted by presser foot lifter to allow fabric of different thickness to pass through.

Arm

Top part that houses the balance wheel and spool pin, used to hold and lift the machine.

Spoon pin

Used to hold reel of thread while sewing.

Balance wheel/hand wheel

Controls movement of needle during stitching process.

Stop motion screw

Stops movement of needle during process of winding bobbin.

Bobbin winder

Holds bobbin when winding it with thread.

Stitch length regulator Adjusts length of stitches.

Table

Holds work during stitching.

Needle clamp

Holds machine needle in place.

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FOOD HYGIENE

ALL HOMESCIENCE NOTES FORM 1-4 WITH TOPICAL QUESTIONS & ANSWERS 

PRIMARY NOTES, SCHEMES OF WORK AND EXAMINATIONS

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