Canning & Preserving For Dummies. Amelia Jeanroy
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In addition to choosing the right canning method, follow these guidelines to guard against food spoilage:
Never use a pressure cooker as a presser canner. They are two different appliances.
Don’t experiment or take shortcuts. Use only tested, approved methods.
Never use an outdated recipe. Look for a newer version. Do not update the directions yourself. Check the publishing date at the beginning of the recipe book. If it is more than 5 years old, find a newer version.
Safe recipes are based on science, not hearsay. If you truly want to use a recipe you find online with no science to back it up, look for an approved version elsewhere.
If your elevation is higher than 1,000 feet above sea level, make the proper adjustments in processing time and pressure for your altitude. See the section, “Adjusting for Your Altitude,” for information on altitudes and processing times.
If you’re pressure canning, allow your pressure canner to depressurize to 0 pounds pressure naturally; don’t take the lid off to accelerate the process.
Allow your processed jars to cool undisturbed at room temperature.
Process your filled jars for the correct amount of time and, if you’re pressure canning, at the correct pressure (both will be stated in your recipe). Make adjustments to your processing time and pressure for altitudes over 1,000 feet above sea level.
Test each jar’s seal and remove the screw band before storing your food.
Checking your equipment
To prevent spoilage, your equipment must be in good shape and working properly:
Have the pressure gauge and seal on your pressure canner tested every year for accuracy. (Weighted gauges don’t require testing.) This service is often offered for free at your local cooperative extension office.
Use jars and two-piece caps that are made for home-canning. Discard any jars that are cracked or nicked.
Never use single-use sealing lids a second time. Always use new lids. The sealant on the underside of the lid is good for only one processing. If your jars do not seal the first time, always replace the lid with a fresh one. There may be a problem with the sealant, despite starting with a new lid.
Check the rubber gasket on reusable lids for signs of wear. With proper care, gaskets can be reused up to eight times before needing to be replaced, depending on whether you are pressure canning or water-bath canning.
Knowing the Acidity Level of Your Food
Knowing the acidity level of the food you’re processing is important because the pH, the measure of acidity, determines which canning method you use: water-bath or pressure canning.
For canning purposes, food is divided into two categories based on the amount of acid the food registers:
High-acid foods include fruits and pickled foods. (For detailed information on identifying and processing high-acid food, refer to Chapter 4.) Foods in this group have a pH of 4.6 or lower. Processing them in a water-bath canner destroys harmful microorganisms.Tomatoes are considered a low-high acid food (or in the low range of high-acid foods). With all of the new varieties of tomatoes, it is now recommended that the home canner add an acid to the canning process, to ensure that the proper acidity is reached every time.
Low-acid foods, primarily vegetables, meat, poultry, and fish, contain little natural acid. Their pH level is higher than 4.6. (Check out Chapter 9 for detailed information on identifying and processing low-acid food.) Process these foods in a pressure canner, which superheats your food and destroys the more heat-resistant bacteria, like botulism.
Adjusting for Your Altitude
Properly processing your home-canned foods destroys microorganisms. Knowing your altitude is important because the boiling point of water and pressure in a pressure canner changes at altitudes over 1,000 feet above sea level. This occurs because the air is thinner at higher elevations. With less air resistance, water boils at a temperature below 212 degrees.
To produce food free from microorganisms at higher elevations, adjust your processing time and pressure to compensate for your altitude. Use the altitude adjustment charts in Chapter 4 (for water-bath canning) and in Chapter 9 (for pressure canning). These adjustments ensure that your food is heated to the correct temperature for destroying microorganisms.
www.whatismyelevation.com and simply type in your Zip code.
Spoiler Alert: Identifying Food Spoilage
Food spoilage is the unwanted deterioration in canned or preserved food that makes your food unsafe for eating. Ingesting spoiled food causes a wide range of ailments, depending on the type of spoilage and the amount of food consumed. Symptoms vary from mild, flu-like aches and pains to more-serious illnesses or even death.
But having said that, the potential for spoiled food shouldn’t stop you from canning. When you understand the workings of these microscopic organisms and enzymes, you’ll know why using the correct processing method for the correct amount of time destroys these potentially dangerous food spoilers. And you’ll have nothing to worry about.
Meeting the spoilers
Mold, yeast, bacteria, and enzymes are the four spoilers. Microorganisms (mold, yeast, and bacteria) are independent organisms of microscopic size. Enzymes are proteins that exist in plants and animals. When one or more of these spoilers have a suitable environment, they grow rapidly and divide or reproduce every 10 to 30 minutes! With this high-speed development, it’s obvious how quickly food can spoil. Some of these create spoilage that can’t be seen with the naked eye (like botulism), while others (like mold) make their presence known visually.