Food has to be protected at all stages-storage, preparation, serving and purchasing

Food hygiene –the careful handling of food in a way that will keep it safe and free from all contaminants

Hygiene at diff stages: Purchase of food-Food should be fresh ,good colour and

desirable flavour . Avoid food with heavy moisture. Storage of food-Main enemies are

rats ,flies ,cockroaches ,dirt. In kitchen adequate storage facilities should be present to keep dry and wet ingredients labeled and stored .

All places of storage should be dry and clean and inspected regularly.

Dry food should be stored in dry tins and bins with tight lids

Perishable food should be kept in ice boxes or refrigerators. Regular cleaning of storage spaces is essential.

Hygiene and Food Safety

Preparation of food :Vegs should be cleaned of dirt and mud ,decayed portion removed and washed well.

Utensils should be kept clean and traces of stale food to be removed.

Food to be cooked at high temp to kill the bacteria.

Food should be well covered with lid. Wash your hands before cooking the food. Keep the floor sink and working surface clean. Serving Food: Food should be eaten as soon

as it is cooked. Food should be served in dishes with covers.

What are microbes?

“Organisms that are too small to beseen with the naked eye”Various members of these groups may cause

changes in the character of food, which may be classed as "positive" or "negative". 

BacteriaVirusesFungiProtozoa

SPOILAGE

Products of "positive" microbial transformations include cheese, yoghurt, and wine, which can be seen as increasing the nutritional value or keeping quality of products with a short shelf life.

Negative" aspects of microbial growth include food deterioration and spoilage by decay, and food poisoning, mainly caused by different and less widespread bacteria. As they grow, micro-organisms release their own enzymes into the liquid surrounding them, and absorb the products of external digestion. This is the main basis of microbial food spoilage, which lowers its nutritional value

+Ve and –Ve

What are bacteria?Unicellular organisms Very small!!!!!!!– 1-10 micronsEnormous diversity– Shape– Habitat– Nutrition

Many bacteria require similar growth andnutrition conditions to humans (very many donot!)

BACTERIA

Everywhere!SoilPlant rootsWaterBodies of animals, fish, birds etc,

Where do we find bacteria?

General features of Fungi

unicellular (yeasts) and multicellular (moulds)Non-photosynthetic, plant-like organismsMulticellular, filamentous organismsNormally inhabitants of the soil, rhizosphereand waterCan tolerate acidic and dry conditions

FUNGI

Meat, poultry, and egg productsOther foods via human carriers

SymptomsAbdominal pain, diaorrhea, fever, chills,

vomiting,dehydration, headache etc

Food Sources

Correct atmosphere (O2)

– aerobic– anaerobic– facultative anaerobes

Correct temperature

What do bacteria need to grow?

Improper storage temperaturesIncorrect storage timesImproper ventilationFailure to separate foodsExcessive delays between receiving and

storingInadequate food safety standards

Common Causes of Food Spoilage

organic food (proteins, carbohydrates, fats) - suitable temperaturemoisture (water) [in some cases] air suitable pH

Conditions for microbial growth

Lots of money is spent on food items by every family.

To take care and get maximum benefit: Proper selection Economic purchase Adequate and safe storage

Storage of food

Perishable foods-Cannot be stored for more than 2-3 days e.g. milk, milk products

Non –perishable foods-Can be stored for longer period of time. e.g. pulses, jam, jelly

Convenience food-Processed or semi-processed food, can be stored for sometime. e.g. Canned fruits and vegs ,milk powder

Storage : Food items

Proper Fruit and vegetable storage can keep the nutrients and vitamins of your particular favorite produce last longer therefore benefiting your body. It also gives you that crisp and crunchy texture instead of the wet noodle texture.

Most veggies should be kept at cool temperatures like around 45-55 degrees. Sweet potatoes should be kept in a dark room. Onions and green tomatoes can be

kept at room temperature  Most of our fruits can be kept in the refrigerator with some exceptions. Bananas,

for example, need to be kept at room temperature. You should only buy as much as you are able to consume in a short period of time.

Most of the melons, like honey dew melon, can be cut and then put up for storage in the refrigerator. Strawberries, grapes, blue berries, raspberries, figs and blackberries can be rinsed off lightly and then put in the refrigerator. 

Cut your lettuce and rinse lightly for about 3 minutes in vinegar water (2/3 water, 1/3 vinegar).

Remove old leaves from vegetables like cabbage, lettuce and the top part of carrots before storing in your refrigerator.

You can use “Fit” fruit and vegetable wash made out of 100% natural sources to clean your fruits and veggies.

Storage of Vegetables and Fruits

Meat will typically store well for 9 months frozen.  Canned meat typically has a shelf life of 1-2 years. Meat can be stored at refrigerator temp just above the freezing point for short period. Freezer is the best place to store meat. 

Wrapping and container protect meat from further contamination and also maintain the moist surface of meat.

Tight wrapping should be removed if the meat is to be kept for two days.

Fresh eggs typically have a refrigerated shelf life of 3-4 weeks.  So keep as many eggs on hand in your refrigerator that you see necessary for your family.  You might also consider storing some egg substitute or dehydrated eggs. 

Egg should not be washed before storing as the organic matter present in the shell gets washed off ,thus making the pores open for micro-organism to attack.

Storage of Eggs and Meat

Fluid milk should be stored in refrigerator for not more than 1 week. Dry milk will store 5-10 years in the absence of oxygen at 70 degrees

Fahrenheit Covering and capping the milk container protects milk from

dust ,bacteria and undesirable flavour Milk should not be exposed to sunlight a and as it looses ascorbic acid

and riboflavin Fish: Taking fresh fish back home to a refrigerated environment is

instrumental towards making sure that it maintains its quality. make sure that you remove it from the store wrapping. Then wipe the surface with a damp cloth to remove any debris, and if they fish is whole, you might want to wash it with cool water and then pat it dry.

Temperatures : 34-36 degrees Fahrenheit or 1-2 degrees Celsius The frozen fish, helps in storage, and also preparing the harmful bacteria

to be killed off as well as preventing it from spoiling. 

Storage of Milk and Fish

It helps to increase food supply during shortage period It increases shelf life of the food.eg fruits It add variety to food.eg in place of fresh beans we

can use dried beans It decreases the wastage of food.eg abundant supply

of mangoes can be preserved as pickles It decreases dietary inadequacy.eg Kashmir apples

reaches all over the world It reduces cost of food and improves nutritional values

eg fish ,egg all over the world Personal satisfaction is gained by getting different

types of food

Importance of Food Preservation

The Fundamental Concepts ofFood Preservation

Basically, all food preservation methods do one ormore of the following to prevent the naturalbiodegradation of food.*Prevent the proliferation(rise) of spoilage

bacteria.*Prevent the rancidity (sour/bad) of fat*Prevent to work of endogenous enzymes.*Prevent the reintroduction of dirt, dust etc afterprocessing (e.g. packaging).

CONDITIONS AFFECTINGBACTERIAL GROWTH

There are 6 conditions affecting bacterial growth

* Food* Acidity* Time*Temperature*Oxygen*Moisture

FOODBacteria need food to reproduce.High protein foods and moist starchy foods promote bacterial growth but any food can be potentially risky is not handled properly.ACIDITYpH-measure of acidity or alkalinity. (pH =7 is neutral; 1=acid; 14=basic).Most bacteria prefer a pH of 5.5-7.5.Most pathogenic bacteria will not grow at a pH of 4.6 or less (acid). Eg fermented foods such as sauerkraut (fermented cabbage) and fermented sausages

TIMEUnder optimal conditions, some bacteria candouble every 20 minutes and increase acc.The colder the storage temperature, the longer the potential shelf life.TEMPERATURE*Bacterial proliferation can be controlled byboth heat and cold. Bacteria generally do not grow at freezertemperatures but they can survive. Use of refrigeration temperatures (30-50F)slows down the rate of bacterial proliferation. The colder the better.

OXYGENSome bacteria require oxygen to grow (aerobic). Some bacteria will only grow if no oxygen is present

(anaerobic). Some bacteria can go with or without oxygen ( facultative).MOISTUREThe amount of water available in food for chemical reactions

and microbial growth is called water activity (Aw).Most spoilage and pathogenic bacteria can only grow in foods

that have a water activity higher than 0.85.The water activity available in foods can be reduced by

freezing, dehydration or adding salt or sugar.(e.g. honey does not foster bacterial

Conditions Effecting BacterialGrowth

1)Control of temperature- CanningUse of heatUse of refrigeration/ Freezing2)Use of Food Ingredients3)Control of Water Activity4)Control of pH5)Packaging

Methods

USE OF HEAT- Pressure Canning and Boiling Water canningPreserves food by heating to high temperatures, driving out

O2.The use of heat can range from a mild cook in thekitchen for pasteurization to total sterilizationPasteurization refers to the application of heat toget a significant reduction in bacteria.Sterilization refers to the application of a lot ofheat and time to render the a food product totallybacteria-free.Pasteurization is mainly important in the reductionof pathogenic bacteria in milk-legally required.The food is first processed and then sealed in airtight

containers

Control of Temperature

pH is the degree of acidity. 7=neutral; Below 7 is acid.Acid foods (below pH=4.6) do not fosterspoilage or pathogenic bacterial growth.Fermented items like pickles, olives, and

other acidified foods are good examples of this method of preservation.

Most fruit jams & jellies have low pHRestricts chemical/biochemical reactions

Control of pH

Water activity is a measurement of the water that is free to use by bacteria.

The goal of using water activity as a preservative method is controlling bacteria.

Beef jerky, cheeses and raisins are classical examples. Honey and jellies are also good examples.

Although they contain enough moisture to foster microbial proliferation, the water is bond by the high sugar content.Bakery items and cereals have a very low moisture

Control of Water Activity

After food in treated or processed, it needsto be kept clean. This area is known as“packaging”.

Packaging can range from a simply plasticfilm ( dust cover) all the way to flexible,oxygen impermeable films and even cansand glass/ plastic jars.

Prevent the Reintroduction ofDirt, Dust etc

Following are the basic methods used to control

Food spoilage.

Methods of Food Preservation

METHODS OF PRESERVATION

Home Refrigeration and FreezingHome Refrigeration: Use refrigerator ,ice box.

Perishable food items like fruits, vegs, fish, meat, curd etc

Fresh and wholesome food should be keptFruits and vegs should be kept in plastic bags in

order to prevent loss of moisture –take care accumulation of water does not take place

Cooked food should be kept coveredRefrigerator must be defrosted and cleanedRefrigerator should not be opened frequently

Use of Low temperature

Refrigeration (at or above 32F) slows down bacteria proliferation(increase) and enzymatic activity.

Most convenient, easiest, fastest methodLow temperatures-Inhibit microbial growthFreezing fruits is sooooo easy!Spread out clean dry berries on a cookie sheet, put

into the freezer; when they’re frozen, put into a freezer bag. Stone fruits like peaches can be

packed in syrup in Tupperware or plastic bags OR dry-packed after sprinkling with sugar & freezing in bags or boxes–

THE USE OF REFRIGERATION/FREEZING

Pasteurization Canning Drying Use of preservatives Use of radiation

Use of high temperature

Refers to preserving milk Milk is heated to 65degree C and kept at

this temp for 30 mins and then cooled down known as holding process

Milk is heated at to 75 degree for 15 sec and is known as flash process

High temp for short time (HTST)

Pasteurization

Heating of food also denatures endogenous enzymes (blanching of vegetables).Canning is

aimed at the total destruction of all bacteria. Cooking can be done in a variety of method

from dry heat methods to deep-fat frying known as sterilization method

The seal of the tin prevents contamination of food and food is preserved for longer period of time

Eg Vegs,fruits,meat

CANNING

Oldest method where moisture space content/removal of water prevents spoilage microbes from growing, as well as enzymatic & chemical reactions

Taste, appearance, & nutritive value notpreserved the way they are with canning orFreezing .Makes good snacks, decreases the wt and bulk in

food –great economy in storage, transportation and packing of food

Dried foods conserve storage-production of convenience foods e.g instant coffee/tea

DRYING -Dehydration

Method used for preservation –aim is to produce maximum drying rate with minimum product damage and economic drying cost

Oven drying Oven drying – when climate is not

appropriate A conventional oven with a thermostatic setting of 140 degree F

Methods of Drying

Fruits, vegetables and meat are preserved by using acids.Acid is generally supplemented by salt or sugar. Spices are supplemented to add

flavour and preservative action. Addition of oil to pickles help in checking the air from coming in contact with

the forming of oil layer.Cucumber, beef, peppers and some vegetables may be preserved by pickling.

This technique involves dipping the food in some liquid chemical that prevents the growth of micro-organisms but still maintains edibility of the food.

The preserving liquids used are vinegar, brine, alcohol and some other oils. This process is known as chemical pickling. (Benzoic acid and Sulphur dioxide )

The other way of pickling is by fermentation. In fermentation pickling, the preservation agent is produced by the food itself during the process of fermentation.

PICKLING

Sugaring is a method used to preserve fruit where the fruit is placed into a sugar based syrup this is popular with apples, pears, apricots and many other fruits.

Sugar absorbs excess water and thus prevents the growth of micro-organism.

Sometimes the fruit is cooked in this syrup and then dried and stored and in some instances the fruit skins are used as dried fruit skins are popular as a delicacy in some countries.

Jams and jellies are the best examples.

SUGARING

Smoking-Food is exposed to smoke by burning a special kind of wood. It helps to remove moisture and gives better flavor to food . Eg Meat ,Fish

Some ingredients are used in foods to increase their shelf-life. All are aimed either at controlling microbial growth or preventing fat rancidity.

Salt tends to reduce bacterial proliferation eg Sodium Nitrite used in cured meats .

Sodium lactate and other antimicrobial agents are used to control bacteria.

Smoking adds appeal in taste & appearanceHeat, chemicals, and surface dehydration work to

preserve food

CURING AND SMOKING

Encourages the growth of some bacteria, which

consume part of the food Example: Yogurt, formed when bacterial

culture is added to milkBacteria eat milk sugars(lactose) & form acidThe pH drops, which inhibits thegrowth of other bacteria

FERMENTING

Packaging can range from a film overwrap (dust cover) to oxygen impermeable film to cans and jars.

In its simplest form, it acts as a dust cover to

prevent the reintroduction of dirt, dust etc.

Packaging

Irradiation is now being used to preserve some foods.The ultra violet or gamma rays are allowed to pass

through packed food to sterilise Spices generally have very high bacteria counts and are

often irradiated to reduce the bacterial numbers.Potatoes destined for long term storage are often irradiated to keep them from spouting.Raw meats are now approved for irradiationmainly as a pasteurization method for the control of

bacteria.

New Methods of FoodPreservation

They are processed with salt (a pro-oxidant),

cooked in oil, which gives them a high, unstable fat content. These factors will cause potato chips to go rancid rather quickly.

They are packaged in an oxygen impermeable film with nitrogen gas atmosphere thereby preventing rancidity.

Potato Chips

Most of them are heat sterilized to kill all bacteria.When processed in the jar or can, oxygen is evacuated before sealing to prevent fat rancidity.

Canned/ Jars of Soups, Fruits andVegetables

Most dairy products are pasteurized whichis a heat-based treatment to reduce bacteria. Sold as refrigerated item. Controls bacterial via cold methods. Are usually packaged to remove oxygen to prevent fat rancidity.Items such as cheeses have a low pH andwater content for extended shelflife.

Milk and Dairy Products

Bacteria is not usually a problem because of low moisture content.Fat rancidity is not a big problem because they are fairly low in fat and some

antioxidants are usually added.

Cereal and Bakery Items

Shelf-life is usually several weeks.Some fruits and vegetables are irradiated or packaged in modified gas atmospheres to control the ripening process and retard microbial growth.

Fresh Fruits and Vegetables

What You Have LearntFOOD AND ITS NUTRIENTS

Functions of food + Nutrients and Nutrition Proteins Carbohydrates Fats Minerals Vit Water Dietary Fibre Five Food groups Hygienic Preparation of food -4 RulesFOOD PRESERVATION

MEANING NEED CAUSES OF FOOD SPOLAGE

PRINCIPLES OF FOOD PRESERVATION

METHODS OF PRESERVATION AT HOMEDehydration Lowering Increasing Preservatives

Temperature Temperature Natural Chemical

Refrigeration Cold storage Freezing Pasteurization Sterilization.WEBSITE TO VISIT http://www.nios.ac.in/SecHmscicour/english/LESSON_05.pdf

http://www.youtube.com/watch?v=sMtuho4QFAQ&NR=1 You tube