In addition to using the freshest fruits and vegetables available when home canning, you need to make sure that other ingredients are the good/safe choices.
Water composition can determine the quality of the final product. Use only water that you know is safe to drink. The quality of the canned product can be affected by the amount of minerals in the water. If hard water is used, high levels of calcium or magnesium can lead to the formation of white precipitate that clouds the brine and eventually settles to the bottom of the jar. This is especially true for low acid foods such as canned green beans. Iron can darken light colored foods or add an unpleasant flavor. Consider using filtered bottled water or one of the commercially available water treatment units that attach to the faucet if minerals in hard water are a problem.
Salt is generally added to foods to enhance their flavor. It can be safely omitted for canning tomatoes, vegetables, meats, poultry, and seafood. However, in fermented sauerkraut and brined pickles, salt not only provides flavor, but also is vital to safety by favoring the growth of desirable bacteria while inhibiting the growth of others. Do not attempt to make sauerkraut or fermented pickles by cutting back on the salt required.
Table salt is safe to use for canning but does contain anti-caking additives that may make the brine cloudy or produce sediment in the bottom of the jar. Iodized salt is not recommended for fermenting pickles or sauerkraut or for canning since it may cause products to darken, discolor, or be spotty. Canning salt or pickling salt is pure salt—- no additives— and is the best choice for canning, pickling and making sauerkraut. Sea salt is evaporated sea water and contains various minerals. It is safe to eat but the minerals may cause canned foods to discolor. Kosher salt is a coarse, flaked, pure salt that can also be used in canning. Since flaked salt may vary in density, it is not recommended for making pickled/fermented foods where salt concentration is a critical factor for microbial growth. Most salt substitutes contain potassium chloride which should never be substituted for sodium chloride (salt) in fermentation recipes. If you want to lower the sodium content in sauerkraut or pickles, rinse the product with water just before heating and serving. NEVER do this before canning since lowering the salt content of fermented products before canning will lower the acid content (raising the pH) and possibly render the product unsafe to eat or quick to spoil.
Acids naturally present or added to foods are an important part of the preservation process. Never change the amount of acid, dilute with water or substitute acid sources unless the recipe specifically allows you to do so. For home preservation purposes, use vinegar labeled as 5 percent acidity since they produce consistent results.
White vinegar is usually preferred when light color is desirable, as is the case with fruits and cauliflower. Do not use homemade vinegar or vinegar of unknown acidity in pickling. Do not dilute vinegar unless the recipe specifies this since you will be diluting the preservative effect. If a less sour product is preferred, add sugar rather than decrease the vinegar. Lemon juice is another acid that is commonly used in home food preservation. To assure safe acidity in whole, crushed, or juiced tomatoes, add 2 tablespoons of bottled lemon juice per quart of tomatoes or 1 tablespoon per pint. An alternative to lemon juice for acidifying tomatoes is citric acid. Citric acid is usually sold as a white crystalline powder. It can safely be used to acidify foods if used correctly. To acidify canned tomatoes described above, add 1/2 teaspoon per quart or 1/4 teaspoon per pint. Citric acid can also be used to preserve the color of fresh cut fruit or as a pre-treatment for frozen and dried fruit. Aspirin should never be used to acidify foods but should only be used for its intended purposes.
For more information about using these ingredients as well as sugars/non-nutritive sweeteners, color enhancers/colorants, texture enhancers and thickening agents in home canning, go to: http://extension.psu.edu/food/preservation/tools/supplies/ingredients/ingredients-used-in-home-food-preservation or contact your local Virginia Cooperative Extension Office.
Jeannie Mullins is the Lee County, Virginia extension agent for family and consumer sciences.