Canning & Preserving For Dummies. Amelia Jeanroy

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      Bacteria

      Bacteria are a large group of single-celled microorganisms. Common bacteria are staphylococcus and salmonella. Botulism, the one to be most concerned with in canning, is the most dangerous form of bacteria and can be deadly. It’s almost undetectable because it’s odorless and colorless. Botulism spores are deadly but can be easily destroyed by heating the food to an internal temperature of 180 degrees Fahrenheit (85 degrees Celsius) for at least 5 minutes. Boiling occurs at 212 degrees Fahrenheit (100 degrees Celsius) and is the safest and easiest way to protect yourself from becoming ill.

      Botulism spores hate high-acid and pickled foods, but they love low-acid foods. When you provide these spores with an airless environment containing low-acid food, like a jar of green beans, the spores produce a toxin in the food that can kill anyone who eats it. The only way to destroy them in low-acid food is by pressure canning.

      

For safety’s sake, before eating any home-canned, low-acid food, boil it for 15 minutes from the point of boiling, if you are at an altitude of 1,000 feet or lower. For altitudes above 1,000 feet, add 1 additional minute for each 1,000 feet of elevation.

Boiling kills the botulism bacteria, but only if boiled until the food reaches an internal temperature of 180 degrees Fahrenheit for at least 5 minutes. Symptoms from ingesting botulism-infected food occur within 12 to 36 hours after eating it. These symptoms include double vision and difficulty swallowing, breathing, and speaking. Seek medical attention immediately if you believe you’ve eaten infected food. Antitoxins are available to treat this poisoning, but the sooner, the better.

      No matter how long you boil your jars, they will never reach a higher temperature than that of boiling water. This is why water-bath canning and pressure canning are not interchangeable.

      Enzymes

      Enzymes are proteins that occur naturally in plants and animals. They encourage growth and ripening in food, which affects the flavor, color, texture, and nutritional value. Enzymes are more active at temperatures of 85 to 120 degrees Fahrenheit than they are at colder temperatures. They’re not harmful, but they can make your food overripe and unattractive, while opening the door for other microorganisms.

      An example of enzymes in action occurs when you cut or peel an apple. After a few minutes, the apple starts to brown. Stop this browning by treating the cut apple with an antioxidant solution (see Chapter 5). Other methods for halting the enzymatic action in your food are blanching (see Chapter 15) and hot packing (see Chapter 5).

      Determining what you need to dispose of

      No one can promise you that your home-canned foods will always be free from spoilage, but you can rest assured that your chances for spoiled food are greatly reduced when you follow the precise guidelines for each preserving method. However, if you suspect, for any reason, that your food is spoiled or just isn’t right, don’t taste it. Instead, take a time-out to better evaluate the contents. For starters, the best way to detect food spoilage is by visually examining your jars. Review the following checklist. If you can answer “true” for each of the following statements, then your food should be safe for eating:

       The food in the jar is covered with liquid, is fully packed, and has maintained the proper headspace.

       The food in the jar is free from moving air bubbles.

       The jars have good, tight seals.

       The food has maintained a uniform color.

       The food isn’t broken or mushy.

       The liquid in the jar is clear, not cloudy, and free of sediment.

      After your food has passed this preliminary checklist, examine your jars more closely. Truth is, just because your food doesn’t look spoiled doesn’t mean that it’s not. If you discover any spoilage during any step of this process, don’t continue your search, but properly dispose of your product.

      1 Hold the jar at eye level.

      2 Turn and rotate the jar, looking for any seepage or oozing from under the lid that indicates a broken seal.

      3 Examine the food surface for any streaks of dried food originating at the top of the jar.

      4 Check the contents for any rising air bubbles or unnatural color.The food and liquid should be clear, not cloudy.

      5 Open the jar.There shouldn’t be any spurting liquid.

      6 Smell the contents of the jar.Take note of any unnatural or unusual odors.

      7 Look for any cottonlike growth, usually white, blue, black, or green, on the top of your food surface or on the underside of the lid.

      

Spoiled low-acid food may exhibit little or no visual evidence of spoilage. Treat any jars that are suspect as if they contain botulism toxins. Follow the detailed instructions for responsibly disposing of spoiled, low-acid food in Chapter 9. Never use or taste any canned food that exhibits signs of spoilage or that you suspect is spoiled. Boiling will not make spoiled food safe to eat.

      

Removing the screw bands from your cooled, sealed jars before storing them allows you to easily detect any broken seals or food oozing out from under the lid, which indicates spoilage. Screw bands can also create a “false seal.” Screw bands that are left on jars can easily corrode and adhere to the jars, making them impossible to open safely.

Part 2

      Water-Bath Canning

IN THIS PART …

      Discover why water-bath canning is the most popular canning method.

      Find new recipes to preserve old favorites for more variety in your pantry.

      Understand why water-bath canning is safe for certain foods and not for others.

Chapter 4

      Come On In, the Water’s Fine! Water-Bath Canning

      IN THIS CHAPTER

      

Discovering water-bath canning

      

Recognizing high-acid foods

      

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