- Canning seems hard to do. I’m overwhelmed! How do I get started?
- Botulism: I’ve heard a lot about botulism poisoning. How concerned should I be? How safe is home canning?
- Seal failure: After cooling, some of my jars have failed to form a tight seal. What do I do now?
- My frozen meats have turned gray. Are they safe to eat?
- Our power went out! Do I have to throw out all of my frozen food?
- Moisture in dried foods: I dried some fruit, but now there is moisture inside the container. Do I need to throw it out?
- You put food and liquid in special jars with lids.
- You heat the jars.
There are two canning methods: boiling water–bath (BWB) canning and pressure canning. BWB canning is easier and a good place to begin.
Probably the biggest mistake people make when canning for the first time is buying too much produce and planning to make a big batch. It turns into an all-day project that leaves you exhausted. The second mistake is making something new that your family may not like. Therefore, recommended first projects are canned tomatoes or perhaps berry jam. Tomatoes are canned with added acid, so are safe for boiling water bath canning. Tomatoes have many uses from spaghetti sauce, to soup, stew, and salsa. Berry jam is a perennial favorite for toast or biscuits. With as little as two pounds of produce, you can create your first few jars in an afternoon.
Canning is also more fun and successful when you take the time to make a plan. The first tasks at the beginning of any canning project are to check equipment and supplies, choose a recipe, and assess what ingredients you need. For your first project, do all of the planning ahead of time, and plan to do the actual canning on another day.
Beside choosing a favorite product, preparing a small batch, and allowing adequate planning time, other ways to ensure a fun, successful canning project is to attend a canning class in your area or enlist a friend and plan your canning projects together. Our grandmothers and great grandmothers often canned along with neighbors or family members, employing the old adage that “many hands make light work”.
Canning and botulism: I’ve heard a lot about botulism poisoning. How concerned should I be? How safe is home canning?
Clostridium botulinum is a common, everyday bacteria found in soil and on food. Only under certain conditions does it become harmful. In the absence of air, such as in canned foods, C. botulinum may produce botulin, the toxin that causes food poisoning. It is relatively easy to make sure that Clostridium bacteria remain harmless.
A century ago, botulism poisoning was a problem due to improperly processed foods canned at home. After research agencies determined the correct methods (time and temperature) to can vegetables and meats safely, the problem disappeared. Today, rare cases of botulism occur when incorrect canning procedures are used.
One way to avoid the issue in canned foods is to process only foods that are high in acid. C. botulinum remains inactive in high-acid environments. This includes canned fruits and fruits products like applesauce and jam, and vegetables with added acid (usually vinegar) such as when making pickles or relish.
For low-acid foods, such as plain vegetables or meat, you need to destroy C. botulinum by heating the food to 240°F, which requires a pressure canner. Inadequate processing of home canned vegetables, meat, and fish have been the primary sources of food-borne botulism poisoning. (The other primary source is untested recipes, such as spaghetti sauce.)
When you are doing home canning, be sure to use tested recipes. Tested recipes give the necessary information to can foods safely and guard against botulism. You also need to practice other normal safety measures in the kitchen. Make sure that you sanitize the work area, wash produce thoroughly, adjust the processing time if you live and can above an elevation of 1,000 feet, follow all procedures accurately, and never take shortcuts.
In addition, before opening and consuming canned food, critically examine canned products for spoilage. As an added precaution, you can boil all home canned vegetables and meats without tasting for 10 minutes (plus 1 minute per 1,000 feet above sea level). Boil home canned spinach and corn 20 minutes before tasting. If the toxin is present, it is readily destroyed by boiling.
Botulism is a rare but serious illness. If untreated, the disease can lead to paralysis, respiratory failure, and death. Symptoms include double or blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness. If you suspect you have food poisoning, see your doctor immediately for treatment.
Canning jar seal failure: After cooling, some of my jars have failed to form a tight seal. What can I do now?
You have two options: reprocess within 24 hours, or simply refrigerate and use within 3 days.
If you reprocess, you must start with a clean jar, heat the product as called for in the original recipe, pack the food in the clean jar, and process for the full amount of time. This method runs the risk of over-processing the food, which makes it safe but may make it unappetizing if it turns soft and mushy.
Therefore, it’s usually easier to simply refrigerate and use the jar soon.
To prevent seal failures, be sure to follow all recommended canning procedures:
- Check jar rims for cracks or chips.
- Always use new lids.
- Keep lids in hot—never boiling—water.
- Use tested recipes.
- Check and adjust headspace accurately.
- Wipe jar rims clean before applying lid. Use vinegar when canning products with oil or fat.
- Use correct processing time for the size of the jar.
- Cool jars undisturbed for 12 to 24 hours before testing seal.
Thaw the meat in refrigerator, trim and discard freezer-burned portions. Cook meats with liquids, such as by stewing, or use to make soup. Pack foods in freezer-safe containers; remove all air from flexible wraps. If food does not fill container, add parchment paper, waxed paper, or foil to take up the extra airspace. Use frozen food within 1 year.
Our power went out! Do I have to throw out all of my frozen food?
Not necessarily. Keep the door closed; cover the freezer (but not the compressor or any vents) with heavy blankets. Food in a fully loaded freezer may stay frozen for 2 to 4 days. A half-filled freezer may keep food frozen only about 24 hours.
To maximize frozen storage time without power, avoid opening the freezer door and cover the freezer with blankets; however, take care not to cover the compressor, which is usually located in the lower rear of the freezer. If needed, ice may be brought in after 24 hours to maintain cold temperatures.
It may be too late this time around, but it’s a good idea to have a plan in place in case of a power outage. Will you use ice or ice packs and picnic coolers to keep your food cold? A generator? Do you have shelf-stable foods to eat, so the freezer door can remain closed? Use other shelf-stable methods of preservation such as drying or canning for some of your food, rather than relying solely on a freezer.
Use a thermometer to monitor the storage temperature of the food. Always discard any food that has been at 40°F for more than 2 hours.
- If food is stored at 40°F or lower, and still contains ice crystals, you may refreeze it.
If food has spoiled in a freezer because of a power failure or some other reason, it is very important to promptly discard the food and clean the interior of the freezer. Turn off or unplug the freezer, defrost if necessary, and allow it to come to room temperature. Clean the warm freezer with a solution made of 1 tablespoon baking soda in 1 quart tap water, or 1 cup of white vinegar in 1 gallon tap water.
Moisture in dried foods: I dried some fruit, but now there is moisture inside the container. Do I need to throw it out?
Unless there is mold present or an off odor indicating spoilage, the food should be safe to eat. Return the fruit to the dehydrator or freeze it for continued safe keeping. You either did not dry the food thoroughly the first time, or the food re-absorbed moisture during storage.
To dry foods thoroughly, cut them into pieces of equal size so that foods dry evenly. After drying food, test several pieces of food, not just 1 or 2, for adequate dryness. Fruits are particularly susceptible to uneven and excess moisture, so it is a good practice to condition fruits.
To condition dried foods, place them in a tightly closed container at room temperature. Stir or shake the contents every day for a week. If you open the container to stir the contents, be sure to close it again tightly. During conditioning, the moisture will equalize—that is, excess moisture will transfer to drier pieces, until it is evenly distributed throughout the batch. During conditioning, if moisture forms on the inside of the container, the food is not sufficiently dry and you need to return it to the dryer.
To store dried foods, package it in airtight containers promptly after drying to prevent the food from reabsorbing moisture. Store dried foods in a cool, dry, dark place. Check for moisture daily during the first week in storage, and then monthly throughout the year.
Food poisoning from home preserved foods is almost always due to handling the food improperly or using incorrect procedures. Be sure to review this list of the most common mistakes that people make when preserving food:
- Improper hand washing
- Carelessly washing produce
- Thawing food at room temperature
- Mingling raw and cooked ingredients
- Pickling and curing at temperatures above 40°F Note: Fermenting is a special type of pickling that is done at warmer temperatures, under strict control, and with special limitations.
- Tasting a food to see if it’s still good The best policy is always “when in doubt, throw it out” (without tasting it).
Symptoms of food poisoning resemble many other illnesses, and can include upset stomach, abdominal cramps, nausea, vomiting, diarrhea, blurred vision, and fever. One of the best things you can do if you suspect you have food poisoning is to drink plenty of water. If symptoms persist or worsen, see a physician.
When healthy adults and children ingest food-poisoning bacteria, they usually do not become seriously ill. However, the following groups are at increased risk for serious side effects and even death from low levels of bacteria:
- Pregnant women and their unborn children
- Newborn babies
- Persons with weakened immune systems, such as people who have HIV/AIDS, have organ transplants, or take certain medications
- Persons with certain diseases including cancer, diabetes, alcoholism, and liver or kidney disease
- Older adults
You can keep up-to-date with federal food poisoning guidelines (how to avoid it, not how to get it!) on FoodSafety.gov, at http://www.foodsafety.gov/poisoning/index.html.