There are many different food preservation methods that can be safely used at home. Here is a list:
a. Canning – Fruits
Fruits are high-acid foods, so they can be safely processed in a boiling water canner. The heat destroys yeasts and molds that may be present in the food and forces oxygen from the product and jars. The result is a tight, vacuum seal as the jar cools, which prevents re-contamination of the product by yeasts and molds.
b. Canning – Vegetables and Meats
Vegetables and meats are low acid foods (pH > 4.6), and they must be canned in a pressure canner. The high heat is sufficient to kill yeasts, molds, bacteria, and also destroy the spores of bacteria such as Clostridium botulinum. In addition, the heat results in removal of oxygen from the product and jar. This results in a tight, vacuum seal as the jar cools.
When foods are pickled, the acidity of the food is increased. This is done by adding acid in the form of vinegar or by allowing fermentation to occur resulting in the natural production of acid in the product. There are two types of vinegar used in pickling. Apple cide vinegar and distilled white vinegar. Apple cider vinegar has a fruity flavor and can be used to pickle fruits. Distilled white vinegar is used for light colored products and products where a fruity flavor is undesirable. The natural acid that is produced is lactic acid and that preserves the product. The acid level allows the products to be safely canned in a boiling water canner. The heat results in the removal of oxygen from the product and the jar. This results in a tight, vacuum seal as the jar cools.
d. Jellied Fruit Products
Jellied fruit products rely on acid in the fruit to limit microbial growth. In addition, sugar and/or pectin is added to bind up water in a product making it unavailable for microbes to grow. Yeasts and molds are destroyed by heating in a boiling water canner which also forces oxygen out of the product and jar. The jars form a tight, vacuum seal when cooled.
Freezing lowers the temperature of foods to a level that halts microbial growth. Water in the product freezes and then becomes unavailable for microbes to grow. What you must remember is that freezing does not sterilize the food. When frozen foods are thawed, precautions must be taken to ensure their safety.
Drying food removes water for it and prevents it from being available for microorganisms to use for growth.