Canning & Preserving For Dummies. Amelia Jeanroy
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in the soil, and even in the air you breathe. Sometimes microorganisms are added to food to achieve a fermented product, like beer or bread (for leavening). They’re also important for making antibiotics. The point? Not all microorganisms are bad, just the ones that cause disease and food spoilage.
Mold
Mold is a fungus with dry spores. Poorly sealed jars of high-acid or pickled foods are perfect locations for these spores to set up housekeeping. After the spores float through the air and settle on one of their favorite foods, they start growing. At first you see what looks like silken threads, then streaks of color, and finally fuzz, which covers the food. Processing high-acid and pickled food in a water-bath canner destroys mold spores.
Yeast
Yeast spores are much less colorful, and grow in food in the same way as mold spores. They’re particularly fond of high-acid food that contains lots of sugar, like jam or jelly. They grow as a dry film on the surface of your food, more commonly inside the food, creating an off flavor and fermentation. Prevent yeast spores from fermenting in your food by destroying them in a water-bath canner.
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.
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.
Part 2
Water-Bath Canning
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