Canned Food 1. Method of preserving food by sealing it in air-tight jars, cans, or pouches, and then heating it to a temperature that destroys contaminating.

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1 Canned Food 1

2 Method of preserving food by sealing it in air-tight jars, cans, or pouches, and then heating it to a temperature that destroys contaminating microorganisms. Application of high temperature and high pressure is necessary for low-acid foods. High-acid foods (pH 4.6 and below) can be processed without too much pressure. It’s acidic condition is enough to prevent growth of spoilage microorganisms. 2

3 French confectioner who, in 1790, discovered that foods sealed in tightly packed containers and subjected to heat was an effective preservation method. Won 12,000 Francs from the French government for publishing a book called The Art of Preserving Animal and Vegetable Substances For Many Years. Foods were placed inside a cork-stoppered, wide- mouthed glass jars, which were heated for hours in a boiling water bath. AppertizationAppertization Discovery  Niclas Appert 3

4 The use of tin cans were patented by Peter Durand in 1810. Tin cans are both lighter and cheaper than glass jars. 4

5 Preparation of Canned Food Product The Heating Process The Cooling Process These practices remove oxygen, destroy enzymes, prevent the growth of undesirable bacteria, yeasts, and molds, help form high vacuum in cans. Can Manufacture The Canning Process 5

6  Canning uses the heat sterilisation method to kill microorganism and theirs spores.  The food is packed in cans and steamed at a high temperature and pressure to drive out all the air.  The cans containing food are then sealed while the food is being cooled.  The vacuum created within the airtight containers during canning prevent the growth of microorganisms. 6

7 Purpose of Canning  Pathogens and food-spoiling bacteria are destroyed and the enzymes in the food are inactivated.  Canning keeps food sterile for long periods hence, the shelf life of canned food is usually longer. 7

8 Do Canned Foods Lose Nutrients?  Fat-soluble vitamins and most minerals are relatively stable, but vitamin A and D lost at high temperatures in presence of oxygen.  Fats - Oxidative rancidity can be increased if oxygen not properly removed from cans.  Protein - Quality of the protein can be improved or impaired 8

9 Do Canned Foods Lose Nutrients?  Three vulnerable water-soluble vitamins Thiamin Riboflavin Vitamin C  Some minerals are added when foods are canned Important in this respect is sodium chloride, salt, which is added for flavoring 9

10 Canning Principles  Heat is applied Container expands  Changes in the internal pressure  Gas escapes  The difference in pressure pulls down the lid and forms a vacuum seal 10

11 Two Methods of Canning Boiling Water Canning Used for high-acid foods Pressure Canning Used for low-acid foods. Can also be used for high-acid foods but might result in a soft texture. 11

12 High-Acid Foods (pH < 4.6)  All fruits, except for: figs Melons  Fermented pickles, such as sauerkraut  Acidified foods, such as pickles and tomatoes 12

13 Low-acid Foods (pH > 4.6)  All vegetables, except for rhubarb  Meats  Poultry  Seafood  Soups  Mixed canned foods (low-acid + high-acid) 13

14 PACKAGING A.Metal º Tin/iron/tin cans º Aluminum B.Glass C.Plastic/metal/fiber flexible pouches 14

15 Raw Pack  For foods that lose shape when cooked.  Place raw food directly in jars. Pour boiling hot liquid over the food.  Pack firmly, do not crush.  Add jars carefully to warm canner to prevent jar breakage from heat shock.  Preheat water to 140 o F before putting raw-packed foods into boiling water bath. 15

16 Hot Pack  Preferred method for most foods.  Food is cooked in liquid before packing. Cooking liquid is then poured over food in jar.  Better food color and flavor.  Easier to pack, foods more pliable  Heat in preparing kills some microorganisms.  Preheat water to 180 o F before putting into boiling water bath. 16

17 Raw Packing Hot Packing filling cans tightly with freshly prepared, but unheated food heating freshly prepared food to boiling, simmering it to 2 to 5 minutes, and promptly filling cans loosely with the boiled food 17

18 is the space from the top of the jar to the food or liquid during processing. If the headspace is not adequate, some food in the container will be forced out leaving the food particles or syrup on the sealing surface and preventing a seal. When too much headspace is allowed, some air may remain in the jar after processing causing the food at the top of the jar to darken. Adequate headspace allows vacuum to form during the processing of the food.HeadspaceHeadspace 18

19 Processing Time  Each food and preparation style has its own processing time so always use a tested recipe.  Time differs with size of jar.  Too little = underprocessing  spoiled or unsafe food  Too much = overprocessing  overcooked 19

20 Fruits and vegetables 6-12 hours after harvest. Freshly slaughtered meats should be canned without delay. Ice fish and other sea foods eviscerate immediately, and can them with 2 days. Simmering vegetables for less than 5 minutes, may be necessary for vegetable products to be canned Processing Schedules 20

21 Cooling Process  Cans are immersed in cold water or can be cooled gradually using warm water and air currents. 21

22 Common Cases of Spoilage Canned Foods Poor selection of product Incorrect processing temperature Incorrect processing time Incorrect pressure Imperfect seal on the can 22

23 Spoilage of canned goods  spoilage prior to canning  underprocessing  leakage of contaminated water into cans during cooling process 23

24 Spoilage caused by Thermophilic spore-forming bacteria Usually results to underprocessing of canned foods because of their heat resistant spores. Flat-Sour Spoilage caused by the development of lactic acid by flat-sour bacteria remains a normal can appearance occurrence in low-acid foods are caused by some Bacillus species occurrence in acid foods are caused by Bacillus coagulans from plant equipments (blanchers), starch, sugar, and soil Bacillus coagulans 24

25 TA Spoilage short for thermophilic anaerobe not producing H 2 S Clostridium thermosaccharolyticum forms acid and gas, which is a mixture of CO 2 and H 2, that could swell or burst the can if held long at high temperature usually has a sour or chessy odor same sources of contamination as those in flat-sour spoilage Sulfide Spoilage or Sulfur Stinker Desulfotomaculum nigrificans uncommonly found in low-acid foods black FeS spots, smelly odor caused by H 2 S same sources of contamination as those in flat-sour spoilage, including manure Desulfotomaculum nigrificans 25

26 Spoilage caused by Mesophilic Bacteria Clostridium species sugar fermenting Clostridium butyricum and Clostridium pasteurianum CO 2 and H 2 gas produced may swell the can Clostridium sporogenes, Clostridium putrefaciens, Clostridium botulinum are putrefactive and produces smelly odors of H2S occurs in canned foods which has been processed less than 100°C Clostridium butyricum Clostridium sporogenes 26

27 could be killed in a short time at 100°C or higher Bacillus subtilis and Bacillus mesentericus grow in low-acid foods which are poorly evacuated Bacillus polymyxa and Bacillus macerans could grow in canned peas, asparagus, peaches, and tomatoes Bacillus species Bacillus subtilis Bacillus macerans 27

28 Spore forming bacteria in heat-processed canned foods indicates leakage of the container, since water is the most frequent source of contamination. Coliform bacteria, produce gas which swells the cans. 28

29 Yeasts Spoilage caused by readily killed by pasteurization treatments due to underprocessing or leakage fermentative yeasts in canned fruits, syrups, or condensed milk, swells the cans because of CO 2 produced film yeasts grow in the surface of pickled foods 29

30 Spoilage caused byMolds acidic and sugar concentrations as high as 70% can permit mold growth Aspergillus, Penicillum, and Citromyces acidification of pH and heating it to 90°C for 1 minute inhibit mold growth Aspergillus flavus Penicillum on Jam 30

31 Storage of Canned Food C anned foods must be stored in a cool, dry place between 10°C - 21°C Avoid storing canned foods in warm or hot places; foods may lose some of its eating quality and may eventually spoil within a few weeks, or months Dampness of the place of storage may cause the cans or metal lids to corrode therefore allowing contamination of microorganisms in leakages causing it to spoil Low-acid foods will retain its optimum eating quality for at least 1 year Consume high-acid foods within 12-18 months; although it will be safe to eat if there’s no signs of spoilage, the color, flavor, and nutritional value may have been degraded 31