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- 1. Principles of Home Food Preservation Fall 2008
- 2. Instructions to modify presentation 1. Copyright: Permission is granted for all use/reuse by U.S.U. Extension. Others may modify the presentation only by placing their logo in the top right side of the slide master template and adding the presenters name in the footer. 2. To modify: In PowerPoint choose [View], then [slide master], then select the last slide down. Here you can modify the corner elements. USU Extension may replace the upper left logo with the USU Extension logo indicating their county. All may add a logo to the upper right corner. USU Extension may change the bottom left graphic and the footer. 3. To change the footer: Choose [Insert][Header-Footer] and type your footer as a replacement for the existing footer. Extension staff should consider placing their web address and phone number here. 4. When finished editing delete this instructional slide before presenting. Please do not delete any other slides. 5. Please report errors or needed corrections to brian.nummer@usu.edu – Thanks. http://homefoodpreservation.usu.edu 2
- 3. …is always just a phone call or mouse click away! http://extension.usu.edu http://foodsafety.usu.edu
- 4. Food Preservation • Freezing • Dehydrating • Canning – Boiling water canning – Pressure canning – Pickling – Jams & Jellies http://homefoodpreservation.usu.edu 4
- 5. Food Safety No. 1 Priority • Use only research tested recipes – USDA Complete Guide to Canning – USU Fact Sheets – NCHFP – Ball Blue Book http://homefoodpreservation.usu.edu 5
- 6. Research Tested Recipes http://extension.usu.edu http://www.freshpreserving.com http://www.homefoodpreservation.com http://homefoodpreservation.usu.edu 6
- 7. Why foods spoil • Yeast • Molds • Bacteria • Enzymes http://homefoodpreservation.usu.edu 7
- 8. Safe Canning • Processing temperature • Processing time • Sealed lid http://homefoodpreservation.usu.edu 8
- 9. Determining Safe Processing • Acid level • Container & size • Preparation method • Consistency of food • Altitude • Research http://homefoodpreservation.usu.edu 9
- 10. Acid Level • pH 4.6. or lower = acid food = BWC processing • pH above 4.6 = low acid food = pressure processing • Why? – botulism! http://homefoodpreservation.usu.edu 10
- 11. High Acid Foods • pH 4.6. or lower • Use Boiling water canner • Temperature reaches 200-212ºF • Tomatoes, jams, fruits, BBQ sauce, http://homefoodpreservation.usu.edu 11
- 12. Low Acid Foods • pH above 4.6. • Use Pressure canner • Temperature reaches 240-250ºF • Vegetables, meat, soups, etc. http://homefoodpreservation.usu.edu 12
- 13. Containers • Mason jars best choice • 4, 8, 16, and 32 oz. common • 64 oz. only for juice • Mayo jars okay • 2-piece metal lids http://homefoodpreservation.usu.edu 13
- 14. Raw Pack & Hot Pack http://homefoodpreservation.usu.edu 14
- 15. Raw Pack & Hot Pack Disadvantages: • Floating food • Air bubbles Disadvantage: • Discoloration over time • Texture loss http://homefoodpreservation.usu.edu 15
- 16. 2 Piece Metal Lids • Always use new lids • Hand tighten • Too loose (leaks) • Too tight (no vacuum) http://homefoodpreservation.usu.edu 16
- 17. Sealing • Remove air bubbles • Wipe rim • Preheat lid (soften sealing compound) • Attach lid • After processing hear seal “pop” remove screw band http://homefoodpreservation.usu.edu 17
- 18. Consistency of Food • Affects heat penetration • Liquid always required • Reason some foods cannot be canned --cubes vs slices --pumpkin butter --no added thickeners --no pasta or noodles http://homefoodpreservation.usu.edu 18
- 19. Altitude • Affects temperature reached when boiling Altitude Temperature (in feet) when water boils • It is temp. reached and not the 10,000 194°F action of boiling that kills microorganisms 8,000 197°F • Higher altitudes need longer 6,000 201°F boiling water time or higher 4,000 204°F pressures in pressure canner 2,000 208°F • Always use tested 0 (Sea Level) 212°F recipe/process http://homefoodpreservation.usu.edu 19
- 20. When to can • Low quality foods make low quality preserves • Always preserve the freshest foods (within hours of harvest) • Before canning: -- Some fruits may be allowed to fully ripen off the vine -- Some meats may be refrigerated for 1-2 days http://homefoodpreservation.usu.edu 20
- 21. Preparing Jars • Wash jars before every use in clean soapy water • Rinse well • Sterilize jars and lids in boiling water only when boiling water canning less than 10 minutes http://homefoodpreservation.usu.edu 21
- 22. Boiling Water Canner • Aluminum or porcelain- covered steel • Flat bottom • Not more than 2” wider than burner • Jar rack or bottom rack needed • Steam canners not recommended http://homefoodpreservation.usu.edu 22
- 23. Boiling Water Canning 1. Fill canner halfway with water. 2. Preheat to 140°F for raw pack and 180°F for hot packed foods. 3. Load filled jars with lids into rack and then lower into water. 4. Add more boiling water to cover jars at least 1 inch. 5. Turn heat to highest setting until water boils vigorously. 6. Start timer once water boils vigorously. http://homefoodpreservation.usu.edu 23
- 24. Boiling Water Canning 7. Cover and turn down heat until gently boiling. 8. Add more boiling water as needed. 9. When time is up turn off heat and remove lid. 10. Remove from canner and set on a towel at least 1 inch apart to cool. 11. After lids seal (pop) remove screw bands. http://homefoodpreservation.usu.edu 24
- 25. Pressure Canner • Aluminum or steel • Lid with gasket • Flat or concave bottom • Weighted or dial gauge (check dial gauge annually) • Pressure safety valve • Jar rack http://homefoodpreservation.usu.edu 25
- 26. Pressure Canning 1. Put 2-3 inches of water in canner, lower rack of filled and lidded jars into canner and fasten cover securely. 2. Heat until steam escapes from vent port. 3. Let steam vent for 10 minutes, then place weight on vent port or close petcock. Allow to pressurize. 4. Begin to time when recommended pressure is reached. 5. Adjust heat to regulate a steady pressure on gauge. http://homefoodpreservation.usu.edu 26
- 27. Pressure Canning 6. If pressure drops below required amount, reset time to zero. 7. When time is completed, turn off heat and let the canner depressurize. DO NOT force-cool the canner- may result in food spoilage. 8. After canner is depressurized, remove the weight from the vent. Wait 2 minutes, remove lid and avoid steam. 9. Remove jars and place on towel or rack to cool. http://homefoodpreservation.usu.edu 27
- 28. Cooling Jars • Do NOT retighten lids • Cool at room temp. 12-24 hours on a rack or a towel http://homefoodpreservation.usu.edu 28
- 30. Reprocessing • If any jar fails to seal or is suspected of not being fully and properly processed it MUST be --immediately refrigerated, then reprocessed (full time with new jars or lids within 24 hours) or eaten http://homefoodpreservation.usu.edu 30
- 31. Storing Canned Foods • Remove screw band • Label and date jar • Do not allow to freeze Clean or overheat Cool • Shelf life: 12-18 mos. Dark boiling water canned & 18-24 mos. for pressure Dry canned http://homefoodpreservation.usu.edu 31
- 32. Spoilage of Canned Foods • Check for swollen lid or seal breakage. • When opening look, smell, and listen for anything unusual: -- off smells -- spurting liquid http://homefoodpreservation.usu.edu 32
- 33. © Utah State Univ. Extension Utah State University is committed to providing an environment free from harassment and other forms of illegal discrimination based on race, color, religion, sex, national origin, age (40 and older), disability, and veteran’s status. USU’s policy also prohibits discrimination on the basis of sexual orientation in employment and academic related practices and decisions. Utah State University employees and students cannot, because of race, color, religion, sex, national origin, age, disability, or veteran’s status, refuse to hire; discharge; promote; demote; terminate; discriminate in compensation; or discriminate regarding terms, privileges, or conditions of employment, against any person otherwise qualified. Employees and students also cannot discriminate in the classroom, residence halls, or in on/off campus, USU-sponsored events and activities. This publication is issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Noelle E. Cockett, Vice President for Extension and Agriculture, Utah State University. Authors: Judy Harris, Debra Proctor, and Brian Nummer USU Cooperative Extension. August 2008. http://homefoodpreservation.usu.edu 33
Editor's Notes
- Foods can be preserved by refrigeration, freezing, dehydrating and canning. Canning can be a safe and economical way to preserve quality food at home. Disregarding the value of your labor, canning homegrown food may save you half the cost of buying commercially canned food. Canning favorite and special products to be enjoyed by family and friends is a fulfilling experience and a source of pride for many people. The advantages of home canning are lost when you start with poor quality fresh foods; when jars fail to seal properly; when food spoils; and when flavors, texture, color, and nutrients deteriorate during prolonged storage.
- Foods can be preserved by refrigeration, freezing, dehydrating and canning. Canning can be a safe and economical way to preserve quality food at home. Disregarding the value of your labor, canning homegrown food may save you half the cost of buying commercially canned food. Canning favorite and special products to be enjoyed by family and friends is a fulfilling experience and a source of pride for many people. The advantages of home canning are lost when you start with poor quality fresh foods; when jars fail to seal properly; when food spoils; and when flavors, texture, color, and nutrients deteriorate during prolonged storage.
- Growth of the bacterium Clostridium botulinum in canned food may cause botulism—a deadly form of food poisoning. These bacteria exist either as spores or as vegetative cells. The spores, which are comparable to plant seeds, can survive harmlessly in soil and water for many years. When ideal conditions exist for growth, the spores produce vegetative cells which multiply rapidly and may produce a deadly toxin within 3 to 4 days of growth in an environment consisting of: a moist, low-acid food, a temperature between 40° and 120° F, and less than 2 percent oxygen –exactly what is achieved when canning food.
- Suppose at the grocery store you saw a display of your favorite brand of canned vegetables or tomatoes in a discount bin. [Hold up “take your chances” can] Because the supervisor had a bad night they can’t guarantee that the product was processed the full time for safety, so they are offering the product at a reduced cost. How do you feel about this ‘Bargain”? [Hold up “guaranteed safe” can] Do you expect commercial canneries to produce products of unquestionable safety? Yes, and we can have the same safety standards in our own canning at home. CURRENT means every year or two call the Extension office (before salsa season) and say, “This year I will be canning X, Y and Z. Have the canning guidelines for those item changed in the last few years? (“Aunt Mildred has made this for 20 years and no one has died yet” is not enough). REMEMBER as you teach youth, neighbors, or friends about canning, do not teach them magic numbers that may change. Teach them how to find current, tested information. (Cooperative Extension is nationwide—the education arm of USDA). Some people have such faith in a lid that seals that they will iron on lids that did not seal after processing. NO!
- Enough heat must reach the center of the jar to control the molds or yeasts or bacteria that might be a risk for that food.
- It is critical to have the lid seal, but that is not enough by itself. There must be enough time for the heat in the boiling water canner or the pressure canner to penetrate the food and control the undesirable microorganisms. Researchers in laboratories repeat the processes again and again until they can guarantee the control of the target microorganism. If you understand some of the factors that affect control of the microorganisms, you will better understand the processing guidelines.
- We will discuss each one of these factors..
- Whether food should be processed in a pressure canner or boiling-water canner to control botulinum bacteria depends on the acidity of the food. Acidity may be natural, as in most fruits, or added, as in pickled food. Low-acid canned foods are not acidic enough to prevent the growth of these bacteria. Acid foods contain enough acid to block their growth, or destroy them more rapidly when heated. The term "pH" is a measure of acidity; the lower its value, the more acid the food. The acidity level in foods can be increased by adding lemon juice, citric acid, or vinegar.
- Acid foods have a pH of 4.6 or lower. They include fruits, pickles, sauerkraut, jams, jellies, marmalades, and fruit butters. Although tomatoes usually are considered an acid food, some are now known to have pH values slightly above 4.6. Figs also have pH values slightly above 4.6. Therefore, if they are to be canned as acid foods, these products must be acidified to a pH of 4.6 or lower with lemon juice or citric acid. Properly acidified tomatoes and figs are acid foods and can be safely processed in a boiling-water canner.
- Low-acid foods have pH values higher than 4.6. They include red meats, seafood, poultry, milk, and all fresh vegetables except for most tomatoes. Most mixtures of low-acid and acid foods also have pH values above 4.6 unless their recipes include enough lemon juice, citric acid, or vinegar to make them acid foods.
- Food may be canned in glass jars or metal containers. Metal containers can be used only once. They require special sealing equipment and are much more costly than jars. Regular and wide-mouth Mason-type, threaded, home-canning jars with self-sealing lids are the best choice. They are available in 1/2 pint, pint, 1-1/2 pint, quart, and 1/2 gallon sizes. The standard jar mouth opening is about 2-3/8 inches. Wide-mouth jars have openings of about 3 inches, making them more easily filled and emptied. Half-gallon jars may be used for canning very acid juices. Regular-mouth decorator jelly jars are available in 8 and 12 ounce sizes. With careful use and handling, Mason jars may be reused many times, requiring only new lids each time. When jars and lids are used properly, jar seals and vacuums are excellent and jar breakage is rare. Most commercial pint- and quart-size mayonnaise or salad dressing jars may be used with new two-piece lids for canning acid foods. However, you should expect more seal failures and jar breakage.
- Raw pack more suitable for vegetables processed in a pressure canner. Hot pack advantages: Many fresh foods contain from 10 percent to more than 30 percent air. How long canned food retains high quality depends on how much air is removed form food before jars are sealed. Shrinks food, helps keep the food from floating in the jars, increases vacuum in sealed jars, and improves shelf life. Preshrinking food permits filling more food into each jar.
- Raw pack more suitable for vegetables processed in a pressure canner. Hot pack advantages: Many fresh foods contain from 10 percent to more than 30 percent air. How long canned food retains high quality depends on how much air is removed form food before jars are sealed. Shrinks food, helps keep the food from floating in the jars, increases vacuum in sealed jars, and improves shelf life. Preshrinking food permits filling more food into each jar.
- Fluids in the canning jar can create convection currents that circulate and help carry the heat from the outer edge of the jar to the center. Jar contents that are thick or viscous will not have convection currents. Heat must travel molecule to molecule by conduction to the center of the jar. If you change the density of the product, the processing time given in the canning recipe will no longer be valid. Examples are simmering salsa 3 hours instead of the stated 30 minutes; adding thickeners such as flour, barley or pasta to stew or soup; adding more solids such as meat, beans or vegetables to soup you are canning.
- Canning guidelines are written for sea level. Guides such as Ball and Kerr have instructions on how to make altitude adjustments, but many people don’t know to look. At sea level water boils at 212 °F., but at Wasatch County altitude it boils at about 202°F. So it will take longer to get the necessary heat to the center of the jar to destroy molds and and yeasts. Water boils at a lower temperature at higher altitude because there is less atmospheric pressure. Thus, more time is required to raise the internal temperature of foods you are processing. In order to kill the bacteria, the processing time or canner pressure must ve increased. Calculate times and pressures at your altitude. Foods will spoil in a sealed jar if the processing time or temperature is not adjusted for altitude.
- Select fresh, firm fruits or vegetables free of spoilage. Do not use bruised or fruit that has dropped to the ground. The acidity changes as the fruit ages and it will affect the safety of the product. Choose freshly killed and dressed, healthy animals. Large chickens are more flavorful than fryers. Dressed chicken should be chilled for 6 to 12 hours before canning. Dressed rabbits should be soaked 1 hour in water containing 1 tbsp. of salt per quart, and then rinsed. Choose quality chilled meat, this includes venison. Eviscerate fish within 2 hours after they are caught. Keep cleaned fish on ice until ready to can.
- Wash empty jars in hot water with detergent and rinse well by hand, or wash in a dishwasher. Unrinsed detergents may cause unnatural flavors and colors. Remove scale build-up and hard water films by soaking jars several hours in a solution containing 1 cup vinegar per gallon of water.
- Wash empty jars in hot water with detergent and rinse well by hand, or wash in a dishwasher. Unrinsed detergents may cause unnatural flavors and colors. Remove scale build-up and hard water films by soaking jars several hours in a solution containing 1 cup vinegar per gallon of water.
- Press the middle of the lid down with finger, if it springs back up the seal is broken…OR Tap the lid with bottom of spoon. If a dull sound occurs the lid is not sealed or food is toughing the bottom of the lid. If sealed a ringing sound will occur…OR Look at jar lid at eye level. Lid should be concave (curved in). If flat or bulging then lid is not sealed.
- If a lid fails to seal on a jar, remove the lid and check the jar-sealing surface for tiny nicks. If necessary, change the jar, add a new, properly prepared lid, and reprocess within 24 hours using the same processing time. Headspace in unsealed jars may be adjusted to 1-1/2 inches and jars could be frozen instead of reprocessed. Foods in single unsealed jars could be stored in the refrigerator and consumed within several days.
- If lids are tightly vacuum sealed on cooled jars, remove screw bands, wash the lid and jar to remove food residue; then rinse and dry jars. Label and date the jars and store them in a clean, cool, dark, dry place. Do not store jars above 95° F or near hot pipes, a range, a furnace, in an uninsulated attic, or in direct sunlight. Under these conditions, food will lose quality in a few weeks or months and may spoil. Dampness may corrode metal lids, break seals, and allow recontamination and spoilage. Accidental freezing of canned foods will not cause spoilage unless jars become unsealed and recontaminated. However, freezing and thawing may soften food. If jars must be stored where they may freeze, wrap them in newspapers, place them in heavy cartons, and cover with more newspapers and blankets.
- Do not taste food from a jar with an unsealed lid or food that shows signs of spoilage. You can more easily detect some types of spoilage in jars stored without screw bands. Growth of spoilage bacteria and yeast produces gas which pressurizes the food, swells lids, and breaks jar seals. As each stored jar is selected for use, examine its lid for tightness and vacuum. Lids with concave centers have good seals. Next, while holding the jar upright at eye level, rotate the jar and examine its outside surface for streaks of dried food originating at the top of the jar. Look at the contents for rising air bubbles and unnatural color. While opening the jar, smell for unnatural odors and look for spurting liquid and cottonlike mold growth (white, blue, black, or green) on the top food surface and underside of lid. Spoiled low-acid foods, including tomatoes, may exhibit different kinds of spoilage evidence or very little evidence. Therefore, all suspect containers of spoiled low-acid foods, including tomatoes, should be treated as having produced botulinum toxin and handled carefully in one of two ways: If the swollen metal cans or suspect glass jars are still sealed, place them in a heavy garbage bag. Close and place the bag in a regular trash container or bury it in a nearby landfill. If the suspect cans or glass jars are unsealed, open, or leaking, they should be detoxified by boiling 30 minutes before disposal.