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Food processing, types , advantages , explanation

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food processing its requirment and its types are explained and the need to process food and the advantages we get from processing food.

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Food processing, types , advantages , explanation

  1. 1. FOOD PROCESSING SUBMITTED TO : DR. HAIDER ALI SUBMITTED BY: Syed wasi haider, Zaid waheed, Amir Sharif, imran khan
  2. 2. What is Food processing and preservation? Food processing is the transformation of cooked ingredients, by physical or chemical means intofood, or of food into other forms. Food processing combines raw food ingredients to produce marketable food products that can be easily prepared and served by the consumer.
  3. 3. FOOD PROCESSING METHODS 1. peeling 2. mincing 3. chopping or slicing 4. emulsification 5. liquefaction 6. baking
  4. 4. WHY DO WE NEED TO PRESERVE FOOD? So that surplus foods from good harvests can be stored and then used in times of shortage. So that we can enjoy seasonal fruits and vegetables all year round. To enable it to be transported long distances without it decaying. To allow it to be stored in the home for long periods without going off
  5. 5. CANNING Uses heat sterilisation to destroy micro-organisms that cause food spoilage. The cans are heated which drives out any air before it is sealed with a double seam to prevent leakage or the re-entry of bacteria. Foods preserved by this method have a long shelf life and can be stored at ambient temperatures. The severity of the heat treatment can be lessened if the food contains acid, salt or sugar. The most important pH is 4.5, as below this the very dangerous organism Clostridium botulinum is inhibited. Cans are cooled in chlorinated water to prevent any possible contamination in cans which may have a slight defect. This could infect the food and cause an outbreak of food poisoning some time later.
  6. 6. 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
  7. 7. FERMENTATION Use of microorganisms to convert foods (raw commodities) into a more stable form. Typically the conversion of carbohydrates into acid or alcohol. Some additional antimicrobial compounds may be formed. THEORY: Reduce the pH of the food or produce substances which make the environment uninhabitable by other organisms.
  8. 8. FACTORS THAT INFLUENCE FERMENTATION 1. Type of organism º natural or starter º acid, oxygen, temperature, º salt tolerance 2. Source of energy 3. Oxygen availability 4. Temperature 5. pH
  9. 9. BOTTLING Toughened glass is used because it can be taken to high temperatures for heat treatment methods such as bottling fruit and vegetables. It is easy to sterilise glass. The bottle (or jar) can be filled either with raw foods and then heated slowly to boil the foods, destroying bacteria and spores. Air is expelled through a specially designed lid, and as the jar cools down, a vacuum is formed. The sealed jar prevents the re-entry of bacteria. As there is no oxygen present, bacteria are unable to multiply. Bottling can also be used for high temperature methods such as jamming, pickling and chutney production. Glass is non-reactive and therefore suitable for use with acidic mixtures. Bottled food has a very long shelf life at ambient temperatures.
  10. 10. PASTEURISATION/ UHT (ULTRA HEAT TREATMENT) Food is heated to temperatures in excess of 100C to ensure that spores are destroyed. In the case of milk the product is heated to not less than 132.2C and is packaged under aseptic conditions. It is similar to pasteurised milk in terms of nutritive value and the heat is so quick the colour and flavour changes are not so obvious as in sterilised milk. The storage life is vastly longer however, for all products that are heated there will be some loss of colour, flavour and texture to a greater or lesser extent. Heat sensitive vitamins e.g. thiamine, riboflavin, niacin and vitamin C will be affected. There’s a reduction of 10-20% of amino acid lysine in high protein foods. Fruit juices may be fortified with additional vitamin C. Packages are hermetically sealed. The packaging materials used are robust and prevent entry of air unless opened or pierced
  11. 11. STERILISATION This process uses a temperature in excess of 100C in order to destroy nearly all micro-organisms present in a food. This is important as some micro-organisms can form spores which have the ability to survive at high temperatures. If the correct temperature is not reached there is the possibility that the spores will germinate and grow and food poisoning could result. Some organisms can survive the sterilisation process if not processed for enough time or a high enough temperature, e.g. Clostridium botulinum. The product is packed in air-tight containers either before or after heat treatment. If packaging follows heating, the containers must be sterilised before use and filled under aseptic conditions. Sterilising enables milk to be kept for 2-3 weeks unopened, but results in a burnt, caramelised flavour and browning
  12. 12. FREEZE-DRYING Not to be confused with AFD (Accelerated freeze-drying) Rapid drying systems cause the outer edges and corners of food to become dried out and rigid thus fix the shape of the food pieces early in the process. Water is removed from the centre of the food to produce a light honeycomb product, which readily rehydrates when added to water (slow drying allows the product to shrink further and produce a dense dried food, which is difficult to rehydrate). As the food is porous the food is excellent for rehydration e.g. coffee, meat, fruit and vegetables. The water- soluble vitamins may be lost from freeze-dried foods. Some odours are lost as a result of this process. Out of all the drying processes, this is the most effective way of maintaining the original characteristics of a product. This is a more costly process, but where colour, texture, flavour, shape and reconstitutability properties are of paramount importance (e.g. cuppa soups, snack pots, coffee), this process gives the most organoleptic results.
  13. 13. SMOKING Process primarily used for meat and fish in combination with salt to add flavour and delay spoilage. The degree of preservation is minimal with this process, because high levels of salt and smoke make the food less palatable and not so good for health reasons. Therefore, in order to preserve smoked products, additional methods such as chilling and vacuum packing are used. Smoking is either hot or cold. In cold smoking the product remains uncooked. The temperature doesn’t exceed 30C. Most products are then cooked, except salmon, which is eaten raw. The organoleptic qualities are considered desirable. In hot smoking the temperature is allowed to rise so that the food cooks. Smoked foods are often coloured yellowy as a result of the process. They are partially dried and salty, so the texture and flavour are distinctive.
  14. 14. SMOKING CONT... Wood Smoking: It contains a number of substances that have antimicrobal activity e.g. formaldehyde and higher aldehydes, phenols and methanol, all of which are highly inhibitory to micro-organism
  15. 15. DRYING Micro-organisms cannot live, grow and reproduce without moisture. It is the removal of moisture by warmth or high temperature. This is an effective method of preservation. Foods can be dried using commercial methods e.g. spray drying, freeze-drying, AFD, tunnel drying and sunlight e.g. tomatoes and fruits or by oven drying e.g. herbs, coffee and vegetables. Dried foods have a long shelf life and can be stored
  16. 16. VACUUM PACKING Foods are prepared and then packed into a pouch or foil wrapper and the air is sucked out, forming a vacuum inside the pack. Removing air takes away oxygen and moisture which bacteria require in order to survive and multiply. Some vacuum packs can be stored at ambient temperatures e.g. coffee and have a medium shelf life. Others stored at chill temperatures e.g. smoked fish, cheese and cured meats. These have a short shelf life. Organoleptic qualities are often maintained
  17. 17. MAP (MODIFIED ATMOSPHERE PACKAGING) Also known as ‘Controlled Atmosphere Packaging’ Preserves food in sealed gas flushed packs In the packs oxygen level can be lowered or the carbon dioxide level or nitrogen levels increased Carbon dioxide retards the growth of bacteria. Oxygen helps retain the colour of the food e.g. meat stays red and nitrogen is used to reduce the rate of oxidation. The ratio of these gasses depends upon the food being packaged. Food is prepared and placed in the container. Container is flushed with selected gas for the food type and is hermetically sealed. MAP is often carried out in conjunction with chilling in case of chilled meals
  18. 18. MAP CONT... Once the packaging is opened the food has a normal shelf life and must be stored accordingly. The packaging used must not be reactive and sufficiently strong to resist damage through piercing or splitting. The most commonly used materials are plastics, which may be ovenable, with a film cover.
  19. 19. IRRADIATION This method of preservation is where ionising radiations are applied to foods to kill bacteria. There is said to be no risk of residual radioactivity and the process should not be confused with radioactive contamination or radioactivity. It is expensive to carry out and as yet is only permitted in the UK for use with some vegetables, spices and poultry products. It extends shelf life by delaying ripening (bananas), inhibiting sprouting (potatoes and onions) and killing moulds (strawberries). It reduces significantly the numbers of pathogenic parasites in meat. No visible changes to irradiated food other than reduction of undesirable factors above. At permitted doses of irradiation, the organoleptic properties of most foods are unaffected
  20. 20. WHY PRESERVE FOOD (ADVANTAGES) Saves money, home preserves cheaper. Avoids waste. Food available out of season. Variety in the diet. Preserved food can be more convenient. Preserved foods can be transported long distances. Creates new flavours, salting, smoking, jam etc.
  21. 21. GENERAL PRINCIPLES OF PRESERVATION To destroy or inactivate enzymes. To destroy or inactivate micro-organisms. To prevent the re-entry of new microbes by sealing food. To maintain the nutritive value, colour, flavour, texture of the food as far as possible.
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