FOOD SPOILAGE AND PRESERVATION

1. FOOD SPOILAGE AND PRESERVATION Facilitator : JasminaSangani

2. Hygiene and Food Safety • 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.

3. 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.

4. SPOILAGE What are microbes? “Organisms that are too small to be seen 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".  Bacteria Viruses Fungi Protozoa

5. +Ve and –Ve • 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

6. BACTERIA What are bacteria? Unicellular organisms Very small!!!!!!! – 1-10 microns Enormous diversity – Shape – Habitat – Nutrition Many bacteria require similar growth and nutrition conditions to humans (very many do not!)

7. Where do we find bacteria? Everywhere! Soil Plant roots Water Bodies of animals, fish, birds etc,

8. FUNGI General features of Fungi unicellular (yeasts) and multicellular (moulds) Non-photosynthetic, plant-like organisms Multicellular, filamentous organisms Normally inhabitants of the soil, rhizosphere and water Can tolerate acidic and dry conditions

9. Food Sources Meat, poultry, and egg products Other foods via human carriers Symptoms Abdominal pain, diaorrhea, fever, chills, vomiting,dehydration, headache etc

10. What do bacteria need to grow? Correct atmosphere (O2) – aerobic – anaerobic – facultative anaerobes Correct temperature

11. Common Causes of Food Spoilage Improper storage temperatures Incorrect storage times Improper ventilation Failure to separate foods Excessive delays between receiving and storing Inadequate food safety standards

12. Conditions for microbial growth organic food (proteins, carbohydrates, fats) - suitable temperature moisture (water) [in some cases] air suitable pH

14. Storage of food 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

15. Storage : Food items • Perishable foods-Cannot be stored for more than 2-3 days e.g. milk, milk products • Semi perishable food: Do not require refrigeration, have limited shelf life, stored for couple of weeks .Namkeens,biscuits,atta,maida • Non –perishable foods-Can be stored for longer period of time. e.g. pulses, jam, jelly • Convenience.

16. Convenience Food • Processed or semi-processed food, can be stored for sometime. e.g. Canned fruits and vegs ,milk powder. They increase shelf life and ease of preparation. • Frozen peas ,jams ,jellies • Most of the food are laden with saturated fat, sodium etc. • These ready food have to be eaten immediately as they have already lost the nutrients present.

17. Storage of Vegetables and Fruits • 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.

18. Storage of Eggs and Meat • 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.

19. Storage of Milk and Fish • 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. 

20. Storage of Semi perishable food • Dry roast suji and dalia before storing • Spices should be stored in dry,air tight container • Potatoes ,onion ,ginger,garlic to be stored in cool dry place. • Ghee ,oil, butter in air tight container bec air and moisture make it rancid. • To preserve paneer cover with blotting paper

21. Storage of Non-perishable food • Pulses,whole grains ,cereals can be cleaned to remove stones or other matter. • Dried in sun , after drying it has to be kept in airtight container. • Home remedies like neemleaves,lumps of salt and turmeric are used to store rice. • Tea ,coffee to be stored in air-tight containers • Sugar has hydroscopic nature ,when exposed to air ,it absorbs moisture,so it has to be stored in dry places

22. Importance of Food Preservation • 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

23. The Fundamental Concepts ofFood Preservation Basically, all food preservation methods do one or more of the following to prevent the natural biodegradation 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 after processing (e.g. packaging).

24. Methods of Preservation 1)Control of temperature- Canning Use of heat Use of refrigeration/ Freezing 2)Use of Food Ingredients 3)Control of Water Activity 4)Control of pH 5)Packaging

25. Control of Temperature USE OF HEAT- Pressure Canning and Boiling Water canning Preserves food by heating to high temperatures, driving out O2. The use of heat can range from a mild cook in the kitchen for pasteurization to total sterilization Pasteurization refers to the application of heat to get a significant reduction in bacteria. Sterilization refers to the application of a lot of heat and time to render the a food product totally bacteria-free. Pasteurization is mainly important in the reduction of pathogenic bacteria in milk-legally required. The food is first processed and then sealed in airtight containers

26. Control of pH pH is the degree of acidity. 7=neutral; Below 7 is acid. Acid foods (below pH=4.6) do not foster spoilage 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 pH Restricts chemical/biochemical reactions

27. Control of Water Activity 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

28. Prevent the Reintroduction ofDirt, Dust etc After food in treated or processed, it needs to be kept clean. This area is known as “packaging”. Packaging can range from a simply plastic film ( dust cover) all the way to flexible, oxygen impermeable films and even cans and glass/ plastic jars.

29. Methods of Food Preservation Following are the basic methods used to control Food spoilage.

30. METHODS OF PRESERVATION

31. Use of Low temperature • Home Refrigeration and Freezing Home Refrigeration: Use refrigerator ,ice box. Perishable food items like fruits, vegs, fish, meat, curd etc Fresh and wholesome food should be kept Fruits 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 covered Refrigerator must be defrosted and cleaned Refrigerator should not be opened frequently

32. THE USE OF REFRIGERATION/FREEZING Refrigeration (at or above 32F) slows down bacteria proliferation(increase) and enzymatic activity. Most convenient, easiest, fastest method Low temperatures-Inhibit microbial growth Freezing 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–

33. Use of high temperature • Pasteurization • Canning • Drying • Use of preservatives • Use of radiation

34. Pasteurization • 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)

35. CANNING 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 EgVegs,fruits,meat

36. DRYING -Dehydration Oldest method where moisture space content/removal of water prevents spoilage microbes from growing, as well as enzymatic & chemical reactions Taste, appearance, & nutritive value not preserved the way they are with canning or Freezing . 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

37. Methods of Drying • 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

38. PICKLING 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.

39. SUGARING 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.

40. CURING AND SMOKING 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 & appearance Heat, chemicals, and surface dehydration work to preserve food

41. FERMENTING Encourages the growth of some bacteria, which consume part of the food Example: Yogurt, formed when bacterial culture is added to milk Bacteria eat milk sugars (lactose) & form acid The pH drops, which inhibits the growth of other bacteria

42. Preservation by Chemicals • Chemicals used to preserve should be properly controlled and non-irritant • Benzoic acid and sulphur dioxide. • Salt of benzoic acid called benzoate increases the presence of carbon dioxide and is used as preservative. • Salt of sulphur dioxide called as potassium meta bisulphite is a crystalline salt . • They delay the growth of micro-organisms

43. Preservation by carbonation • Moulds and yeast require oxygen for their growth and they become inactive in presence of carbon-dioxide. • Higher dose of carbon-dioxide should be avoided as it may destroy the flavour of the juice.

44. Packaging • 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.

46. New Methods of FoodPreservation 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 irradiation mainly as a pasteurization method for the control of bacteria.

47. Household Method of Preservation Canning Preservation of food in sealed containers-application of heat i.e sterilisation Microorganisms ,spores, enzymes are killed and packed in airtight containers Containers used: Glass ,tin cans Advantages; breaking is eliminated Cans are sealed before processing Process of heating is fast Cans can be cooled after processing.

48. Canning Operations • Food is processed for destruction of moulds and yeast during storage • Bacteria ,yeast are destroyed at 100degree centrigade. • Foods like tomato have low pH, do not allow the growth of bacteria. • Foods like beans have high pH-beans can be canned with low ph tomato • Food is inspected and unwanted materials are removed. After blanching , food is placed by hands, depending on nature of product . When item is arranged in the can they are covered with boiling syrup, juice or water and the top is covered . after the exhausting air/vapours the food is permanently sealed.

49. Freezing • Quickest and simplest • Modern freezing equipment permits the rapid freezing of food-natural flavour, texture ,colour and good appearance. • Freezing foods is the art of preparing, packaging, and freezing foods at their peak of freshness. You can freeze most fresh vegetables and fruits, meats and fish, breads and cakes, and clear soups and casseroles. The keys to freezing food are to make sure it’s absolutely fresh, that you freeze it as quickly as possible, and that you keep it at a proper frozen temperature (0 degrees). • Properly packaging food in freezer paper or freezer containers prevents any deterioration in its quality.

50. Addition of sugar • Sugar preserves food by lowering the water activity (aw). If the aw is 85 or less, spoilage and pathogenic microorganisms can't grow. Microorganisms all need proper food, water, temperature and acidity to grow and adding sugar to appropriate levels can prevent bacterial growth.Jams and jellies. • Sugar is used to preserve fruits, either in syrup with fruit such as apples, pears, peaches, apricots, plums or in crystallized form where the preserved material is cooked in sugar to the point of crystallization and the resultant product is then stored dry.