Canning Tomatoes and Tomato Products
Organisms that cause food spoilage - molds, yeasts and bacteria - are always present in the air, water and soil. Enzymes that may cause undesirable changes in flavor, color and texture are present in raw fruits.
When tomatoes are canned, they are heated hot enough and long enough to destroy organisms that can make people sick in addition to spoilage organisms. This heating (or processing) also stops the action of enzymes that can spoil food quality.
Tomatoes are treated as an acid food for canning purposes. Many tomato products may be safely canned in a boiling water canner. However, because some tomatoes can be slightly low-acid for canning purposes, added acid is required in the boiling water canning of plain tomatoes, juice and sauce.
Directions for canning a variety of tomato products are given on the following pages. Some recipes will give you the option of canning either in a pressure canner or in a boiling water bath. Some will give only boiling water bath times and others will give only pressure canning times. The recipes that specify only pressure canning have so many low acid ingredients added to them that they are only safe when canned in a pressure canner at the specified pressure.