10 Tips for Safe Home-Canned Food
Ashley Svaty, Food Safety and Health Agent
Home-canned foods are a year-round treat. But if those foods are not canned safely, foodborne illness can turn a treat into tragedy. Use current canning methods and follow these tips to can foods safely.
1. Adjust for Altitude- Kansas altitudes can range from below 1,000 feet to just over 4,000 feet. Failure to adjust for altitude will lead to under processed food, which could cause foodborne illness.
Use the publication found here to make altitude adjustments
2. Headspace- Proper headspace helps ensure a good vacuum seal on jars. Too little headspace can compromise the seal. Food and liquid expands during processing and may seep underneath the sealing compound.
3. Processing Equipment-Processing methods that are recommended for home canning are water bath canners for high-acid foods and pressure canners for low-acid foods. The following old methods are not recommended and may cause spoiled food and foodborne illness:
4. Untested or Homemade Recipes- Canning your favorite recipe is risky, and may cause spoilage and make you sick. It is difficult to determine the safety of a homemade recipe without having detailed knowledge of the recipe, preparation procedures, total acid content, and consistency of the final product. Use tested recipes from trusted resources such as USDA, K-State Research and Extension publications, or home preserving equipment and ingredient manufacturers. Commercially canned foods are rigorously tested for safety. It is dangerous to recreate them at home.
5. Acidifying Tomatoes- Tomatoes are on the borderline between a low-acid and high-acid food. Tomato processing recommendations include both boiling water and pressure canning. Pressure processing instructions are equivalent in heat treatment to water bath processing. Both methods require acidification. There are no recommendations to process tomatoes without acidification.
6. Improper Processing Time- Use trusted resources for safe processing instructions. Guessing can lead to under processing and foodborne illness or to over processing and poor quality food.
7. Lids and Jars- Recipes specify what size of jar to use. If a recipe lists pints only, do not use a larger jar. Regular and wide-mouth Mason-type, threaded, home-canning jars with self-sealing lids are the best choice. Half-gallon jars are only used for canning high acid juices. With careful use and handling, Mason jars may be reused many times. The common self-sealing lid consists of a flat metal lid and a metal screw band. These lids are used one-time only. Reusing metal lids can lead to seal failure and spoilage. Lids manufactured since 2014 do not require heat treatment before use. All lids, however, can be heated gently in hot simmering water. Do not boil lids as excessive heat softens the gasket compound too much. Metal screw bands can be reused.
8. Modifying Tested Recipes- Adding thickeners, pasta, rice, or any other ingredient to tested recipes can result in spoilage and foodborne illness. These changes alter the acidity and consistency, which slows heat penetration. Instead, make the recipe as stated, then add extra ingredients before serving.
9. Fancy Pack- Fancy packs are not practical and produce potentially unsafe products. Processing times depend on specific preparation procedures. For example, preparation instructions specify cutting carrot pieces, instead of packing them whole. Fancy packs can slow heat penetration through the jar of dense food. The slow process of fancy packing hot food will cool the food too much, resulting in under processing.
10. New Appliances- Food preservation manufacturers are selling new appliances to help consumer preserve food without a lot of expertise or in smaller batches. These appliances must be used according to their instructions and recipes. Use of recipes not developed for these appliances can lead to seal failure, food spoilage, and other potential health risks.
Content for this article is from K-State Research and Extension’s publication “10 Tips for Safe Home-Canned Food”. For access to this publication and other food preservation resources, contact a Post Rock District Office or email Ashley at asvaty@ksu.edu
Home-canned foods are a year-round treat. But if those foods are not canned safely, foodborne illness can turn a treat into tragedy. Use current canning methods and follow these tips to can foods safely.
1. Adjust for Altitude- Kansas altitudes can range from below 1,000 feet to just over 4,000 feet. Failure to adjust for altitude will lead to under processed food, which could cause foodborne illness.
Use the publication found here to make altitude adjustments
2. Headspace- Proper headspace helps ensure a good vacuum seal on jars. Too little headspace can compromise the seal. Food and liquid expands during processing and may seep underneath the sealing compound.
3. Processing Equipment-Processing methods that are recommended for home canning are water bath canners for high-acid foods and pressure canners for low-acid foods. The following old methods are not recommended and may cause spoiled food and foodborne illness:
- Open Kettle Canning- In this method, hot food is poured into jars and the lid and ring are applied with no further heat processing. This allows bacteria, yeast, and mold to grow and spoil food. Examples include inverting hot jars and sun canning.
- Oven- Oven temperatures vary with the accuracy of oven regulators and air movement. Dry heat moves slowly through jars, allowing bacteria to grow. Jars may crack due to temperature shock.
- Dishwasher- Use the dishwasher to wash empty jars and keep them hot, do not use it for processing filled jars. The water temperature is not high enough to kill bacteria.
4. Untested or Homemade Recipes- Canning your favorite recipe is risky, and may cause spoilage and make you sick. It is difficult to determine the safety of a homemade recipe without having detailed knowledge of the recipe, preparation procedures, total acid content, and consistency of the final product. Use tested recipes from trusted resources such as USDA, K-State Research and Extension publications, or home preserving equipment and ingredient manufacturers. Commercially canned foods are rigorously tested for safety. It is dangerous to recreate them at home.
5. Acidifying Tomatoes- Tomatoes are on the borderline between a low-acid and high-acid food. Tomato processing recommendations include both boiling water and pressure canning. Pressure processing instructions are equivalent in heat treatment to water bath processing. Both methods require acidification. There are no recommendations to process tomatoes without acidification.
6. Improper Processing Time- Use trusted resources for safe processing instructions. Guessing can lead to under processing and foodborne illness or to over processing and poor quality food.
7. Lids and Jars- Recipes specify what size of jar to use. If a recipe lists pints only, do not use a larger jar. Regular and wide-mouth Mason-type, threaded, home-canning jars with self-sealing lids are the best choice. Half-gallon jars are only used for canning high acid juices. With careful use and handling, Mason jars may be reused many times. The common self-sealing lid consists of a flat metal lid and a metal screw band. These lids are used one-time only. Reusing metal lids can lead to seal failure and spoilage. Lids manufactured since 2014 do not require heat treatment before use. All lids, however, can be heated gently in hot simmering water. Do not boil lids as excessive heat softens the gasket compound too much. Metal screw bands can be reused.
8. Modifying Tested Recipes- Adding thickeners, pasta, rice, or any other ingredient to tested recipes can result in spoilage and foodborne illness. These changes alter the acidity and consistency, which slows heat penetration. Instead, make the recipe as stated, then add extra ingredients before serving.
9. Fancy Pack- Fancy packs are not practical and produce potentially unsafe products. Processing times depend on specific preparation procedures. For example, preparation instructions specify cutting carrot pieces, instead of packing them whole. Fancy packs can slow heat penetration through the jar of dense food. The slow process of fancy packing hot food will cool the food too much, resulting in under processing.
10. New Appliances- Food preservation manufacturers are selling new appliances to help consumer preserve food without a lot of expertise or in smaller batches. These appliances must be used according to their instructions and recipes. Use of recipes not developed for these appliances can lead to seal failure, food spoilage, and other potential health risks.
Content for this article is from K-State Research and Extension’s publication “10 Tips for Safe Home-Canned Food”. For access to this publication and other food preservation resources, contact a Post Rock District Office or email Ashley at asvaty@ksu.edu
