Food Processing and Preservation

Food Processing and Preservation,,,,,Lecture 01

1. Food Processing and Preservation Course No: FET 227 Presented By Mohammad Afzal Hossain, Faculty, Dept. of Food Engineering and Tea Technology

2. What is Food Preservation?

3. Introduction I want eat a mango in winter season? Is it possible? Why not ! it is possible

4. Food Preservation Introduction How it is possible? I will tell you how it is possible

5. You know that mango cold drinks available in all season Some food like mango pickle is also available throughout the year.

6. How does it not spoil when stored for much time?

7. Do You know that how the food is Preserved? I will Explain Food Preservation

8. Food Preservation Food Preservation is a process in which Food and vegetables are prevented from getting spoilt The color, test, and nutritive values of food is also preserved Food products lasts for a long period of time: Shelf life of food product is increased

9. So, we can defined Food Preservation as: Retaining food over a period of time without being contaminated by pathogenic organisms or chemicals and without losing its colour , texture, flavour and nutritious value. Food Preservation usually involves preventing the growth of bacteria, fungi and other microorganisms, as well as retarding the oxidation of fats which causes rancidity.

10. Why to preserve foods? Why should we preserve foods? I will explain it

11. Types of foods Food Types Perishable Semi Perishable Shelf Stable Fruits Milk Cheese, Some ready foods Grains

12. Food types Perishable - Lasts for less time 2 days to 1 week - Example: Fruits, milk, vegetables, meat Semi perishable - Lasts for around 2 months and are processed - Example: Ice-cream, cheese, bread, cake, pastries Shelf Stable - Has longer shelf Life more than 6 months - Example: Food grains

13. Why to preserve food? If we are able to preserve foods, we enjoy any kind of foods in any season We eat food even it is not available in our areas We can store our food easily and without worries

14. Explanation of previous slide We enjoy any kind of food in any season and different types. Such as Mango juice Mango pulp Mango pickle Raw mango powder etc

15. Principles of Food Preservation Inhibit the growth and activity of Microorganisms -Asepsis(to keep out microorganisms) -Removal of microorganisms -Stopping the growth and activity of microorganisms (low temperatures, drying or chemicals) -Destruction of MO(heating or radiation)

16. Principles of Food Preservation(contd.) 2. Protecting against self decomposition of food -Inhibit the activity of Endogenous Enzyme ( Phenolase ) -Delay or inhibit chemical reactions(Non-enzymatic browning) Protection from invasion and spoilage by insects and rodents Protection against losses by mechanical causes

17. Importance of Food Preservation: Important and vital in the Food industry due to a number of - social , psychological , and health factors Increases the shelf life of food Retain the quality of food – colour , texture, flavour & nutritional value Increases food supply Adds variety to the food Decreases wastage of food Make foods available throughout the year

18. Food Preservation Methods Preservation methods vary according to --------the food items, and --------quantity of the items to be preserved Principles of Food preservation can be broadly classified into two types: Bactericidal methods Bacteriostatic methods

19. Bactericidal methods: Most of the microorganisms are killed Examples are- cooking, canning, pasteurization, sterilization, irradiation etc.

20. Bacteriostatic Methods: Based on prevention of multiplication of microorganisms May be achieved by ----removal of water ----use of acids, oils or spices ----keeping the foodstuff in low temperature Methods based on this principles are ----Drying, ----freezing, ----pickling, ----salting, and ----smoking.

21. Techniques of Food Preservation Physical Chemical Physical -- freezing and canning (rely on killing the microorganisms or at least stopping the their growth for long enough) -- drying, gamma irradiation, exposure to ultraviolet or high intensity white light, ultra high pressure and filtration

22. Chemical Preservatives Work either as: Direct microbial poisons or, Reducing the pH to a level that prevents the growth of MOs #Chemicals used today are: Nitrates and Nitrites ----to preserve meats 2 . Sulphites ----to prevent the browning of fruits and vegetables, ----to prevent fungal spoilage

23. Common food preservation methods: Bottling and canning Pickling Drying Salting Vacuum packing Cooling and freezing Waxing Pasteurization Boiling Smoking

24. Bottling and canning Bottling and canning are processes of preserving food by heating and then sealing it in an airtight container. The food is boiled to kill microorganisms and then sealed to prevent other microorganisms from getting in.

25. Bottling Canning

26. PICKLING Pickling food in vinegar or other acids, makes it difficult for microorganisms to live. Commonly pickled food include onions, parkias , soya beans and chillies . Sugar can also be used in pickling fruits such as nutmegs, mangoes and cherries.

27. The concentrated sugar solution used draws water from the fruit thus preventing the growth of microorganisms.

28. Drying A lot of food is preserved by drying under the sun. Drying removes most water from food. Most bacteria die or become inactive when the food is dried.

29. Anchovies and dried chillies are examples of dried food

30. A lot of fruits such as raisins, guavas and papayas can be eaten dried.

31. Salting Salting is an age-old way of preserving food. The salt draws out moisture and prevents microorganisms from growing. In this process, food such as fresh fish are gutted, washed and coarse salt is rubbed into it.

32. A lot of our local foods are preserved by salting process.

33. Vacuum Packing Vacuum packing keeps food by sucking air out from its packaging. Food is thus prevented from spoiling because there is no air.

34. Vacuum packing is commonly used for storing nuts, sliced fish, pickled and dried fruit.

35. Cooling and Freezing Cooling and freezing are the most common forms of food preservation.

36. Cooling slows down the action of microorganisms, thus it takes longer to spoil. It allows fruit from different parts of the world to appear on our supermarket shelves.(0 to -4 C) At freezing temperature, microorganisms become inactive, thus food cannot spoil when it is frozen. (-18 C)

37. Food like meat, fruit and vegetables are kept in the refrigerator.

38. Waxing Waxing of fruit and vegetables is also common. Apples, oranges, eggplants and tomatoes are dipped into liqiud wax to prevent growth of fungi and loss of moisture. Waxed fruit need to be washed thoroughly or peeled before eating.

39. Pasteurization Pasteurization means heating food to a certain temperature for some time followed by rapid cooling. Heating at such high enough temperature kills most bacteria. However, it does not affect the taste and nutritional value of the food.

40. Fresh milk, yoghurt drink and juices are pasteurized to make them last longer.

41. Boiling As food is heated and cooked, the heat kills the microorganisms, Boiling kills most bacteria. However, those not affected by heat will grow when the conditions are suitable. Boiling kills bacteria

42. Smoking Smoking is the process of drying food with smoke for a long period of time. This method is mainly used for fish, meat and fruit such as banana. The drying effects of smoke and the chemicals produced from the smoke help to preserve the food. Smoked banana smoked meat

43. Food Processing Food processing is the set of methods and techniques used to transform raw ingredients into food or to transform food into other forms for consumption by humans or animals either in the home or by the food processing industry . Food processing typically takes clean, harvested crops or slaughtered and butchered animal products and uses these to produce attractive, marketable and often long-life food products. Similar process are used to produce animal feed .

44. Food Processing From Farm To Table ? Whey protein, a by-product of cheese manufacturing, is used in energy bars and drinks!

45. Aims of Food Processing 1. To extend the shelf life to allow time for distribution, sales and home storage. 2. To increase variety in the diet by providing a range of attractive flavours , colours , aromas and textures in food (collectively known as eating quality, sensory characteristics or organoleptic quality); . 3. To provide the nutrients required for health (termed nutritional quality of a food). 4. To generate income for the manufacturing company.

46. © [email protected] 46 Careers in Food Processing Job Titles: Process Engineer Engineer Employers: Food processors Ingredient manufacturers/suppliers Academia (Higher Education) Contract research laboratories/development firms Self-employed/Consultant Responsibilities: Process design Bench-top process development Testing Plant scale-up Commercialization Troubleshooting

47. Food Processing divided into: Unit operations combination of procedures to achieve the intended changes to the raw materials. Unit operations are grouped together to form a process. The combination and sequence of operations determines the nature of the final product .

48. Food Processing Examples of food processing methods include: Chopping Mixing Homogenizing Cooking Pastuerizing Blanching Spray-drying Frying Baking Packaging Addition of gas such as air entrainment for bread or gasification of soft drinks

49. Dehydration Dehydration (or drying) is defined as ‘the application of heat under controlled conditions to remove the majority of the water normally present in a food by evaporation’ (or in the case of freeze drying by sublimation). The main purpose of dehydration is to extend the shelf life of foods by a reduction in water activity This inhibits microbial growth and enzyme activity, but the processing temperature is usually insufficient to cause their inactivation.

50. Dehydration Drying causes deterioration of both the eating quality and the nutritional value of the food. Examples of commercially important dried foods are coffee, milk, raisins, and other fruits, pasta, flours (including bakery mixes), beans, nuts, breakfast cereals, tea and spices. There are a large number of factors that control the rate at which foods dry, which can be grouped into the following categories processing conditions nature of the food drier design.

51. Blanching Blanching serves a variety of functions, one of the main ones being to destroy enzymatic activity in vegetables and some fruits, prior to further processing by heat. As such, it is not intended as a sole method of preservation but as a pre-treatment which is normally carried out between the preparation of the raw material and later operations (particularly heat sterilisation , dehydration and freezing. Blanching is also combined with peeling and/or cleaning of food, to achieve savings in energy consumption, space and equipment costs

52. Blanching A few processed vegetables, for example onions and green peppers, do not require blanching to prevent enzyme activity during storage, but the majority suffer considerable loss in quality if blanching is omitted or if they are under-blanched. To achieve adequate enzyme inactivation, food is heated rapidly to a pre-set temperature, held for a pre-set time and then cooled rapidly to near ambient temperatures . The factors which influence blanching time are: • type of fruit or vegetable • size of the pieces of food • blanching temperature • method of heating .

53. Pasteurisation Pasteurization is a relatively mild heat treatment, in which food is heated to below 100ºC . In low acid foods (pH>4.5, for example milk) it is used to minimize possible health hazards from pathogenic micro-organisms and to extend the shelf life of foods for several days. In acidic foods (pH <4.5, for example bottled fruit) it is used to extend the shelf life for several months by destruction of spoilage micro-organisms (yeasts or moulds) and/or enzyme inactivation

54. Canning A method of preserving food by killing all microorganisms present in the food and then sealing out air The food, container, and lid are heated until sterile As the food cools, the lid makes an airtight seal, preventing contamination

55. Extrusion A process by which the form of a food is changed Such as changing corn to corn chips Not a preservation measure In this process, the food is heated, ground, and pushed through various kinds of screens to yield different shapes

56. Frying Frying is a unit operation which is mainly used to alter the eating quality of a food. A secondary consideration is the preservative effect that results from thermal destruction of micro-organisms and enzymes, and a reduction in water activity at the surface of the food (or throughout the food, if it is fried in thin slices). The shelf life of fried foods is mostly determined by the moisture content after frying: foods that retain a moist interior (for example doughnuts, fish and poultry products which may also be breaded or battered), have a relatively short shelf life, owing to moisture and oil migration during storage.

57. Irradiation Ionising radiation takes the form of Gama-rays from isotopes or, commercially to a lesser extent, from X-rays and electrons. It is permitted in 38 countries to preserve foods by destruction of micro-organisms or inhibition of biochemical changes.

58. The main advantages of irradiation are as follows: there is little or no heating of the food and therefore negligible change to sensory characteristics packaged and frozen foods may be treated fresh foods may be preserved in a single operation, and without the use of chemical preservatives energy requirements are very low changes in nutritional value of foods are comparable with other methods of food preservation processing is automatically controlled and has low operating costs.

59. Chilling Chilling is the unit operation in which the temperature of a food is reduced to between 1 º C and 8ºC. It is used to reduce the rate of biochemical and microbiological changes, and hence to extend the shelf life of fresh and processed foods. It causes minimal changes to sensory characteristics and nutritional properties of foods and, as a result, chilled foods are perceived by consumers as being convenient, easy to prepare, high quality and ‘healthy’, ‘natural’ and ‘fresh’.

60. Chilling Chilling is often used in combination with other unit operations (for example fermentation or pasteurization) to extend the shelf life of mildly processed foods. There is a greater preservative effect when chilling is combined with control of the composition of the storage atmosphere than that found using either unit operation alone.

61. Freezing Freezing is the unit operation in which the temperature of a food is reduced below its freezing point and a proportion of the water undergoes a change in state to form ice crystals. The immobilization of water to ice and the resulting concentration of dissolved solutes in unfrozen water lower the water activity ( a w) of the food Preservation is achieved by a combination of low temperatures , reduced water activity and, in some foods, pre-treatment by blanching.

62. The major groups of commercially frozen foods are as follows: • fruits (strawberries, oranges, raspberries) either whole or pureed, or as juice concentrates • vegetables (peas, green beans, sweet corn, spinach, and potatoes) • fish fillets and sea foods (cod, plaice, shrimps and crab meat) including fish fingers, fish cakes or prepared dishes with an accompanying sauce • meats (beef, lamb, poultry) as carcasses, boxed joints or cubes, and meat products (sausages, beefburgers, reformed steaks) • baked goods (bread, cakes, fruit and meat pies) • prepared foods (pizzas, desserts, ice cream, complete meals and cook–freeze dishes).

63. Packaging Food is packaged for many purposes. Some reasons are : containment for shipping, dispensing, unitizing in to appropriate sizes, improving the usefulness, protect from microbial contamination, physical dirt, insect invasion , light exposure, flavor pickup, flavor loss, moisture pickup , moisture loss and physical abuse Food is packaged in metal cans, glass & plastic bottles, paper & paper board, wide variety of plastic & metallic films and combinations of these Packaging is done by continuous automatic machines at a speed of 1000 units per min The container forming is dependent on the type of the food