by Karen Ward
The most important thing to do when you're filling your jars is to release trapped air bubbles between the food pieces. This may seem unimportant, but air bubbles can play havoc with your final product:
Jar seals: Too much air in the jar from trapped air bubbles produces excessive pressure in the jar during processing. The pressure in the jar is greater than the pressure outside the jar during cooling. This imbalance interferes with the sealing process.
Liquid levels: Air bubbles take up space. When there's trapped air between your food pieces before sealing the jars, the liquid level in the jar drops when the food is heated. (For releasing air bubbles, see Figure 3-3.) In addition, floating and discolored food results from packing your food without the proper amount of liquid in the jars. Snuggly packed food eliminates air and allows enough liquid to completely cover the food with proper headspace (refer to Figure 3-2).
Never skip the step of releasing air bubbles.
Choosing the right canning method and following proper procedures
Always use the correct processing method for your food. Process all high-acid and pickled food in a water-bath canner. Process all low-acid food in a pressure canner. To find out how to determine whether a food has a low or high acidity level, head to the next section. (You can find out about the different canning methods in Chapters 4 and 9.) In addition to choosing the right canning method, follow these steps to guard against food spoilage:
Figure 3-3: Releasing air bubbles from your filled jars.
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Never use an outdated recipe.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.
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 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 is often offered for free at your local extension office.
Use jars and two-piece caps made for home-canning. Discard any jars that are cracked or nicked.
Never 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.
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. 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.
If you want to feel like you're back in science class all over again, you can buy litmus paper at teacher- or scientific-supply stores and test the acidity level of your food yourself. Also referred to as pH paper, litmus paper is an acid-sensitive paper that measures the acid in food. When you insert a strip of pH paper into your prepared food, the paper changes color. You then compare the wet strip to the pH chart of colors that accompanies the litmus paper.
The pH, or potential of hydrogen, is the measure of acidity or alkalinity in food. The values range from 1 to 14. Neutral is 7. Lower values are more acidic, while higher values are more alkaline. The lower the pH value in your food, the more acidic it is.
Avoiding 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, flulike 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 any one or more of the 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.
Living microorganisms are all around — in your home, 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.
Don't eat food that's had fuzz scraped off of it. This was thought safe at one time but not anymore. Mold contains carcinogens that filter into the remaining food. Although the food appears to be noninfected, ingesting this food can cause illness.
Yeast
Yeast spores grow on food like 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. 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 stubborn and difficult to destroy.
Botulism spores hate high-acid and pickled foods, but they love low-acid foods. When you provide these spores wi
th 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 at altitudes of 1,000 feet or lower. For altitudes above 1,000 feet, add 1 additional minute for each 1,000 feet of elevation.
Boiling does not kill the botalism bacteria. Symptoms from ingesting botulism-infected food occur within 12 to 36 hours after eating it. 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.
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 in temperatures of 85 to 120 degrees 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 or bacteria.
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 and hot packing.
Adjusting 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.
If you don't know the elevation of your city, check with your city offices, your public library, or your state or county cooperative extension service listed in your local telephone directory. Or check out http://national4-hheadquarters.gov/extension/index.html on the Internet. Just enter your city and state in the box at the bottom of the page, click Submit, and scroll down to find the elevation of your city.
Detecting Spoiled Foods
No one can't 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. If you suspect, for any reason, that your food is spoiled or just isn't right, don't taste it. Also, just because your food doesn't look spoiled, doesn't mean that it's not.
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, 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 the previous checklist, examine your jars more closely. 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 contained 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.
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 that indicates spoilage.
Part II
Water-bath Canning
In this part . . .
This part tells you all you need to know about the most popular method of canning: water-bath canning. Some of the products, like jam, jelly, marmalade, relish, and salsa may be familiar to you, while others, like chutney, conserves, and pickled vegetables, may be new. Packed with easy-to-follow instructions for canning a wide variety of fruits, jellies, and more, this part sends you well on your way to a pantry stocked with healthy and delicious items.
Chapter 4: Come On In, the Water's Fine! Water-bath Canning
In This Chapter
Discovering water-bath canning
Recognizing high-acid foods
Stepping up to high-altitude canning
Knowing the proper processing procedures
With water-bath canning you essentially use a special kettle to boil filled jars for a certain amount of time. Common foods for water-bath canning include fruits and tomatoes, as well as jams, jellies, marmalades, chutneys, relishes, pickled vegetables, and other condiments.
You're probably wondering whether water-bath canning is safe for canning food at home. Rest assured: The answer is a most definite "Yes!" — provided that you follow the instructions and guidelines for safe canning.
In this chapter, you discover which foods are safely processed in a water-bath canner and step-by-step instructions for completing the canning process. In no time, you'll be turning out sparkling jars full of homemade delicacies to dazzle and satisfy your family and friends.
Water-bath Canning in a Nutshell
Water-bath canning, sometimes referred to as the boiling-water method, is the simplest and easiest method for preserving high-acid food, primarily fruit, tomatoes, and pickled vegetables.
To water-bath can, you place your prepared jars in the a water-bath canner, a kettle especially designed for this canning method (see the section "Key equipment for water-bath canning" for more on the canner and other necessary equipment); bring the water to a boil; and then maintain that boil for a certain number of minutes, determined by the type of food and the size of the jar. Keeping the water boiling in your jar-filled kettle throughout the processing period maintains a water temperature of 212 degrees. This constant temperature is critical for destroying mold, yeast, enzymes, and bacteria that occur in high-acid foods.
Water-bath canning is one of the two recommended methods for safely home-canning food (the other method is pressure canning, covered in Chapter 9). Although each processing method uses different equipment and techniques, the goal is the same: to destroy any active bacteria and microorganisms in your food, making it safe for consumption at a later time. This is accomplished by raising the temperature of the food in the jars and creating a vacuum seal.
Water-bath canning and pressure-canning methods aren't interchangeable because the temperature of a water bath only reaches 212 degrees while the temperature of a pressure canner reaches 240 degrees, the temperature necessary to sa
fely process low-acid foods. For more on pressure canning, go to Chapter 9.
Foods you can safely water-bath can
You can safely water-bath can only high-acid foods — those with a pH factor (the measure of acidity) of 4.6 or lower. So just what is a high-acid food? Either of the following:
Foods that are naturally high in acid: These foods include most fruits.
Low-acid foods that you add acid to, thus converting them into a high-acid food. Pickled vegetables fall into this category, making them safe for water-bath canning. You may change the acid level in low-acid foods by adding an acid, such as vinegar, lemon juice, or citric acid, a white powder extracted from the juice of acidic fruits such as lemons, limes, or pineapples. Some examples of altered low-acid foods are pickles made from cucumbers, relish made from zucchini or summer squash, and green beans flavored with dill. Today, tomatoes tend to fall into this category. They can be water-bath canned, but for safety's sake you add a form of acid to them.
If your recipe doesn't tell you which processing method (water-bath canning or pressure canning) is appropriate for your food, don't guess. Instead, use litmus paper to test the pH level of your food (see Chapter 3). If your food has a pH of 4.6 or lower, use the water-bath canning method; if it has a pH of 4.7 or higher, use the pressure-canning method.
Key equipment for water-bath canning
Just as you wouldn't alter the ingredients in a recipe or skip a step in the canning process, you don't want to use the wrong equipment when you're home-canning. This equipment allows you to handle and process your filled jars safely.
The equipment for water-bath canning is less expensive than the equipment for pressure canning (check out Chapter 9 to see what equipment pressure canning requires). Water-bath canning kettles cost anywhere from $25 to $45. In some instances, you may purchase a "starter kit" that includes the canning kettle, the jar rack, a jar lifter, a wide-mouth funnel, and jars for about $50 to $60. (If you don't have a supplier near you, check out Chapter 22.)