There are 3 main methods of food preservation: canning, freezing and drying. The method you choose will depend on whether there are safe guidelines for preserving your food using that method; and which method best suits your needs. For instance, you may want to can a new salsa recipe, but if there are no safe guidelines for doing so, you may end up freezing the product instead. Or, if you have a bounty of delicious strawberries from your garden, you might consider canning strawberry jam, or freezing the berries ‘as is’ … but not drying, because drying strawberries results in a poor quality product. Canning, freezing and drying, if done correctly, can help you store safe, high quality food for later use.
There are an estimated 76 million cases of foodborne illness every year in the United States (Mead et al, 1999), resulting in 325,000 hospitalizations and 5,000 deaths and costing the U.S. economy an estimated $5 billion annually. Of the 76 million illnesses, the federal government estimates that: Bacteria account for 5 million illnesses and 1,500 deaths. Some of these bacteria you have probably heard of such as Salmonella and E. coli O157:H7; others, such as Campylobacter, are probably less familiar, but very important in terms of numbers of illnesses caused. Parasites account for 2.5 million illnesses and 800 deaths. Toxoplasma gondii is an unfamiliar parasite to many, but affects an estimated 225,000 people each year, with pregnant women and their unborn fetuses at risk for severe consequences for illness due to toxoplasmosis. Viruses account for 31 million illnesses and 2,700 deaths each year. Common foodborne viral infections are Norovirus and hepatitis A. But, as you can see from this table, the vast majority of foodborne illnesses are caused by some unknown agent. Many mild cases of foodborne illness are not reported, so getting an accurate count and determining the cause of all illnesses is virtually impossible.
An outbreak of foodborne illness occurs when a group of people consume the same contaminated food and two or more of them come down with the same illness. It may be a group that ate a meal together somewhere, or it may be a group of people who do not know each other at all, but who all happened to buy and eat the same contaminated item from a grocery store or restaurant. For an outbreak to occur, something must have happened to contaminate a batch of food that was eaten by a the group of people. Often, a combination of events contributes to the outbreak. A contaminated food may be left out a room temperature for many hours, allowing the bacteria to multiply to high numbers, and then be insufficiently cooked to kill the bacteria. The Center for Science in the Public Interest identified a total of 5,316 outbreaks of illness linked to specific foods between 1990 and 2005. The food categories most commonly linked to outbreaks were: Seafood – 1,053 outbreaks and 10,415 illnesses Produce (fruits and vegetables) – 713 outbreaks and 34,049 illnesses Poultry – 580 outbreaks and 17,661 illnesses Beef – 506 outbreaks and 13,873 illnesses Eggs – 352 outbreaks and 11,224 illnesses What do you notice about this data? I hope you recognize that each of these foods is a good or excellent source of nutrients for microbial growth. Also notice that the greatest number of illnesses over the 15 year period (1990 to 2005) was linked not to meat but to produce (fruits and vegetables); and scientists believe that this trend will continue. Think back to foodborne illness outbreaks linked to produce that you have heard about – maybe it was a national outbreak linked to spinach or chopped lettuce. Why do you think the number of illnesses for produce might be so high? If you guessed that fresh produce (fruits and vegetables) are often not cooked, you would be absolutely correct. Thoroughly cooking meats, eggs and seafood can be an excellent way to prevent illness, but we often don’t cook fruits and vegetables and this sometimes makes them riskier foods in terms of foodborne illness. Before we turn our attention to some of the organisms responsible for these illnesses, take a moment to listen to Dr. Carl Winters, a Food Scientist at the University of California –Davis, and his tips for preventing foodborne illness.
Depending on the method of home food preservation that you choose, you may have a variety of recipes to choose from, or your choices may be limited. Every year, check to make sure your canning recipes are up-to-date. Leave the creativity behind when home canning! Don’t experiment with your health and that of your family. Be sure that you: Use recipes as they are written, don’t adapt . Changing the amount of sugar and salt is sometimes OK, but making other changes is generally not alright. As we talk about specific recipes later this summer, I will make sure to mention if any modifications are safe. For instance, it generally isn’t OK to add more onion or celery than is called for; it isn’t OK to add butter or flour if it isn’t called for; and it isn’t OK to use a larger jar and ‘guess’ on the processing time. It also isn’t OK to leave a critical ingredient like acid out of canned tomatoes. Follow current recipes. Research published in 1994 indicated that some canning procedures were no longer safe. For instance, before 1994 it appeared to be safe to can tomatoes without added acid, but we now know that this isn’t true. So, if your canning recipes pre-date 1994, be sure to order new publications. Call for help BEFORE canning, not after. If you aren’t sure if you are following a safe method, call your county extension office before you start, not while you are waiting for the jars to cool.
Always start with high quality produce. Start with tested varieties. Check current UWEX recommendations for varieties of fruits and vegetables recommended for your area. Seed catalogues, too, are a good source of information. If you have your own garden, pick produce at the proper stage of maturity. Don’t pick under-ripe fruit or immature vegetables, unless your recipe calls for those. The quality of fruits and vegetables don’t improve after harvest. It’s better to hold some fruits of a day or 2 in the refrigerator as you wait for other fruits to ripen, rather than picking fruit that isn’t ready yet. The same holds for vegetables that are not yet mature. Carefully inspect all fruits and vegetables, and discard those that are obviously diseased. Small blemishes can be trimmed away, but it may be unsafe to can diseased produce. Once harvested, fruits and vegetables should be chilled as soon as possible to avoid deterioration in quality. And most produce should be washed before chilling. Harvest produce early in the day. If you shop at a farm market for produce, do your shopping early and then return home to chill or process the produce that you selected.
Before you step into the kitchen, check your equipment to see that you have everything that you will need for a successful food preservation season. If you can both high- and low-acid foods, then you will need at least a pressure canner, and most people have a boiling water canner too. Your canner must be fitted with a rack to hold the jars off the bottom of the canner. Any large pot with a tight-fitting lid and rack can serve as a BW canner. Pressure canners come in 2 types, dial gauge and weighted gauge canners. Dial gauges must be checked every year for accuracy. Your county extension office can help you with this. Now is a good time to check your gauge, before green beans and corn are ready for processing. Check the rubber gasket on your pressure canner too , and replace it if necessary. Inspect your supply of jars and lids. Home canning jars should be free of cracks, scratches and nicks. Replace jars that are damaged. And be sure to use only appropriate home canning jars. For pressure canning you MUST use standard home canning jars, like Mason or Ball jars. For BW canning, you CAN use mayo or spaghetti sauce jars, as long as they take a standard 2-piece lid. Because the sealing compound will deteriorate, you will want to purchase new lids every season. Don’t try to use last year’s lids, as they may not seal. If you plan to freeze produce, clean our your freezer to make room for this year’s supply. Produce that was frozen last year will be lower in quality and have less nutritional value than fresh produce. Plan to use up last year’s frozen food, or compost fruits and vegetables that you can not consume before this year’s crop is ready. Purchase containers that you will use to store frozen foods. Bring your dehydrator out of storage, and give it a thorough cleaning so you are ready for the season.
Before you step into the kitchen, check your equipment to see that you have everything that you will need for a successful food preservation season. If you can both high- and low-acid foods, then you will need at least a pressure canner, and most people have a boiling water canner too. Your canner must be fitted with a rack to hold the jars off the bottom of the canner. Any large pot with a tight-fitting lid and rack can serve as a BW canner. Pressure canners come in 2 types, dial gauge and weighted gauge canners. Dial gauges must be checked every year for accuracy. Your county extension office can help you with this. Now is a good time to check your gauge, before green beans and corn are ready for processing. Check the rubber gasket on your pressure canner too , and replace it if necessary. Inspect your supply of jars and lids. Home canning jars should be free of cracks, scratches and nicks. Replace jars that are damaged. And be sure to use only appropriate home canning jars. For pressure canning you MUST use standard home canning jars, like Mason or Ball jars. For BW canning, you CAN use mayo or spaghetti sauce jars, as long as they take a standard 2-piece lid. Because the sealing compound will deteriorate, you will want to purchase new lids every season. Don’t try to use last year’s lids, as they may not seal. If you plan to freeze produce, clean our your freezer to make room for this year’s supply. Produce that was frozen last year will be lower in quality and have less nutritional value than fresh produce. Plan to use up last year’s frozen food, or compost fruits and vegetables that you can not consume before this year’s crop is ready. Purchase containers that you will use to store frozen foods. Bring your dehydrator out of storage, and give it a thorough cleaning so you are ready for the season.
Before you step into the kitchen, check your equipment to see that you have everything that you will need for a successful food preservation season. If you can both high- and low-acid foods, then you will need at least a pressure canner, and most people have a boiling water canner too. Your canner must be fitted with a rack to hold the jars off the bottom of the canner. Any large pot with a tight-fitting lid and rack can serve as a BW canner. Pressure canners come in 2 types, dial gauge and weighted gauge canners. Dial gauges must be checked every year for accuracy. Your county extension office can help you with this. Now is a good time to check your gauge, before green beans and corn are ready for processing. Check the rubber gasket on your pressure canner too , and replace it if necessary. Inspect your supply of jars and lids. Home canning jars should be free of cracks, scratches and nicks. Replace jars that are damaged. And be sure to use only appropriate home canning jars. For pressure canning you MUST use standard home canning jars, like Mason or Ball jars. For BW canning, you CAN use mayo or spaghetti sauce jars, as long as they take a standard 2-piece lid. Because the sealing compound will deteriorate, you will want to purchase new lids every season. Don’t try to use last year’s lids, as they may not seal. If you plan to freeze produce, clean our your freezer to make room for this year’s supply. Produce that was frozen last year will be lower in quality and have less nutritional value than fresh produce. Plan to use up last year’s frozen food, or compost fruits and vegetables that you can not consume before this year’s crop is ready. Purchase containers that you will use to store frozen foods. Bring your dehydrator out of storage, and give it a thorough cleaning so you are ready for the season.
pH is the measure of acidity in a food. Foods with a pH below 4.6 are high in acid; fruits are high in acid and can be boiling water canned. Acidified foods (foods where we add acid) like pickles and salsa (and tomatoes) are also high in acid and can be water bath canned. Some fermented foods are also high in acid. Foods that are low in acid have a pH above 4.6. Meat, cheese, vegetables, and a few fruits have a pH above 4.6. Foods with a pH above 4.6 (meat/vegetables) must be pressure canned.
Some home canning practices to avoid at ALL COSTS: Do not use a boiling water canner for low-acid foods. Always use a pressure canner for low-acid foods. You risk botulism poisoning if you do not. Never open-kettle can foods. Open-kettle canning is when you place hot food in hot, clean jars and seal, with no further processing. Open kettle canning is NOT acceptable for any type of foods: fruits, tomatoes, or vegetables. With open kettle canning you risk spoilage or even food poisoning. Never oven can foods. Oven canning is when you place canning jars with food such as meat in the oven, heat the jars for a period of time, remove the jars and seal. The jars are likely to break, and the food is not heated sufficient to ensure safety. Here’s an easy way to explain why oven canning does not ensure safety. Think of the last time you had your oven heated to 375 degrees F. You can open the oven door, and place your hand in the oven and, as long as you don’t touch anything, you can leave your hand there a few seconds. But, consider holding your hand over a kettle of boiling water. The boiling water is at 212 degrees F, 163 degrees cooler than the oven, and yet your hand is instantly burned by the steam. So…we can say that dry heat (like an oven) does not act in the same way as moist heat (steam). In home canning we use steam in a pressure canner, or boiling water in a BWC to create the heat needed to ensure safe food.
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