By Diane Wright Hirsch, MPH, RD

Extension Educator/Food Safety

canning tomatoesEvery year, about this time, I am spending time on the phone, talking people out of canning. Well, not exactly. I strongly encourage canning as a way to preserve summer tomatoes, peaches, apples and cucumbers (often as pickles). But, invariably I will answer the phone and on the other end of the line is someone who wants to can their FAMOUS salsa recipe (or pickles, or pesto, or peppers in oil). While I could write volumes on “What Not to Can”, salsa is the subject of this article.

The word “salsa” is the Spanish word for sauce. The Encyclopedia of American Food & Drink reports that the first mention of the term “salsa” appeared in print in the U.S. in 1962. As of 1991, they said, sales of salsa surpassed ketchup.

The origins of these sauces may be Aztec, when the traditional ingredients included tomatoes and chili peppers. But the creative cook can easily find recipes using a variety of ingredients such as beans, mangos, pineapple, grilled corn, avocado, or peaches. Historically, “salsa” was considered an uncooked sauce (salsa fresco or salsa cruda). But, in the interest of convenience, salsa is now most often processed in glass jars and found on the supermarket shelf next to taco shells, tortillas and refried beans (or in plastic tubs in the produce section).

Making and canning salsa in a commercial processing operation is one thing. Doing it at home is another.

Most salsa recipes are a mixture of low-acid foods (such as onions and peppers), with more acid foods (such as tomatoes). Often, there are additional acid ingredients that may include vinegar and citrus juices such as lemon, lime, or orange.

The types and amounts of ingredients used in salsa, as well as the preparation method, are important considerations in how a salsa is canned. Generally, acid foods (tomatoes, fruits) are safely canned in a boiling water bath canner. So folks may think that a tomato or fruit based salsa would also be safely canned in a water bath canner. However, once you add low-acid ingredients such as onions, peppers, black beans, corn, cilantro or avocado, the pH (measure of acidity) balance may be tipped to the low-acid side. At this point, the pH is likely at 4.6 or higher and the only safe way to can the product is in a pressure canner (to safely can in a water bath canner the product pH must be below 4.6).

If a salsa has enough low acid ingredients to render the final product, “low acid” by definition, then you run the risk of having a salsa that will support the production of deadly toxin by the Clostridium botulinum bacteria. Improperly canned salsas or other tomato-pepper combinations have been implicated in more than one outbreak of botulism poisoning. Follow these considerations for safe salsa:

Choose and use safe ingredients

The acid ingredients help preserve canned salsas and make them safe for water bath canning. Most often bottled vinegar or bottled lemon juice is used. Use only commercial and bottled products. An equal amount of bottled lemon juice may be substituted for vinegar in recipes, but do not substitute vinegar for lemon juice. This substitution will result in a less acid and potentially unsafe canned salsa. If the product is to “acidic” or tart for your taste, add a bit of sugar to offset. Do NOT cut down on the acid!

Tomatoes and/or fruit ingredients should be just ripe, free of cuts, rot, or mold. Do not reduce the quantity in the recipe. Overripe tomatoes may be too low in acid for safety. If green mangoes are called for in the recipe, do not use ripe mangos as they also may be too low in acid for safety.

Peppers, onions, and other low acid ingredients must also be added in amounts given in the recipe. An extra pepper might just throw you into the low acid realm…measure and count carefully.

Spices such as cumin, dried oregano, salt and pepper can be adjusted to taste. However, fresh herbs such as cilantro (a low acid ingredient) should be added according to the recipe. You can always add the fresh herbs just before serving for the freshest flavor.

Choose and use a safe recipe

The USDA/Extension mantra has always been, “Only use tested, science-based home-canning recipes from reliable sources like the National Center for Home Food Preservation and some equipment or home preserving ingredient manufacturers.” This is especially true for any acidified food like salsa or pickles. Then, follow the directions, ingredient list, and amounts listed in the recipe. Never add flour, cornstarch or other thickeners—this will have an effect on the processing time needed to heat the interior product to a safe temperature. Store opened salsa in the refrigerator once opened.

If you want to stick with a personal favorite recipe, there are two things you can do. Can a basic salsa and add additional ingredients (beans, corn, avocado) just before serving. Or, make your FAMOUS salsa and store it in the refrigerator for up to one week or freeze it for up to one year. Freezing will certainly affect the texture of your fresh salsa, so test out a small portion first to see if you like it.

For more information about making and preserving salsa, go to www.uga.edu/nchfp (National Center for Home Food Preservation). On that site you will find the fact sheet (some of the information in this article was from this fact sheet), Canning Your Own Salsa Recipe. Or contact the Home and Garden Education Center at ladybug@uconn.edu or 1-877-486-6271.