Skip the navigation header

K-State Logo K-State Research and Extension logo
go to Research and Extension home page go to News go to Publications and Videos ask a question or make a comment search the Research and Extension site


News Logo Search News:   
News Home About Us Staff Links Contact Us

Released: September 05, 2007

Freezing and Canning Tips Can Reduce Risks from Homemade Salsa

MANHATTAN, Kan. – Wet weather early in Kansas’ growing season helped to produce a bumper crop of garden vegetables that is stimulating interest in home food preservation, said Karen Blakeslee, Kansas State University Research and Extension food scientist.

Increasing interest in farmers’ markets, where food comes from and how it is handled also is driving interest in home food preservation, Blakeslee said.

Why Does Food
Chemistry Matter?

MANHATTAN, Kan. – A kitchen is a lot like a chemistry lab, said Karen Blakeslee, Kansas State University Research and Extension food scientist.

“Recipes are typically formulated with consideration for each ingredient’s food chemistry,” she said. “Failure to follow a recipe may change flavor, texture, or appearance as well as the food chemistry.”

Whether a food is acid or alkaline can, for example, make a difference in whether it can host microorganisms that cause foodborne illness, said Blakeslee, who recommends choosing tested recipes from trusted sources and following them.

Using tested recipes for home canning is a lot less expensive than a visit to the emergency room, Blakeslee said.

More information on food and food safety is available at county and district K-State Research and Extension offices and on Extension Web sites:  and

One need not be a veteran in the kitchen to succeed, but the food scientist urged caution, using homemade salsa as an example.

“Salsa typically includes tomatoes, a highly acidic ingredient, and onions and peppers that are low-acid foods. Recipes may call for adding vinegar, lemon or lime juices or other ingredients that also will impact the acidity of the overall recipe.

“Failing to balance the acid level when mixing ingredients in the salsa can create an environment in which foodborne bacteria – including Clostridium botulinum (Botulism), which can cause double vision, paralysis, vomiting and death – can grow,” Blakeslee said.

So, is there a way to enjoy fresh garden vegetables in homemade salsa safely?

“Yes,” said Blakeslee, who offered these tips:

* Choose fresh, top-quality ingredients that are free of cracks, bruises, mold or insect damage.

* Wash vegetables thoroughly to remove debris.

* Choose a tested recipe that is known to yield satisfactory results when directions are followed. Recipe sources include the county or district K-State Research and Extension office; the United States Department of Agriculture (Web site: and search for canning recipes); the National Center for Home Food Preservation (; the “Ball Complete Book of Home Preserving,” and the “Ball Blue Book,” which may be available at libraries, and for purchase at book, hardware and kitchen supply stores and some supermarkets.

* Read the recipe to make sure that you have all ingredients and equipment on hand before beginning to prepare the recipe.

* Do not alter the amounts of ingredients in recipes. This will affect the safety of the final product. If you want to alter a tested recipe, wait to add extra ingredients (additional peppers, seasonings, etc.) until right before serving. It is possible to substitute different types of peppers to increase – or decrease – the heat in the salsa, and also possible to use any variety of tomatoes or substitute tomatillos for some of the tomatoes.

* To can a homemade recipe of salsa in a pressure canner, evaluate processing times for each ingredient and then use the longest processing time. For example, in a mixture of tomatoes, peppers and onions, the onions have the longest processing time.

* Consider freezing, rather than canning. Freezing will protect garden-fresh flavors and reduce the risks of foodborne illness. Freezing also allows flexibility – and creativity – in preparing your salsa recipe. If frozen salsa may become mushy, drain as needed before serving. Homemade salsa can typically be frozen for up to 12 months.

* If home canning is preferred, a hot water bath or pressure canner is recommended because the final heat treatment will kill bacteria that may be present. Today’s salsa recipes will use a water bath processing method. If using a pressure canner, check the accuracy of the pressure gauge at the beginning of food preservation season and more often, if a malfunction is suspected. Many K-State Research and Extension offices offer this service.

* Do not use the open kettle method for any kind of canning. This process involves ladling food into hot sterilized jars and applying the lid without further heat processing. The open kettle canning method may cause foods stored at room temperature to spoil and can lead to foodborne illness.

* Canning jars, lids and screw-top rings, which are made to withstand heat, should be sterilized and ready to go. Canning jars and screw-top rings in good condition can be re-used; sealing lids should be not re-used. If a jar is not made for canning, heat involved in the process may cause it to explode.

* Store home-canned foods in a cool (60 to 70 degrees), dry (to prevent lids from rusting) and dark (sunlight may cause temperature fluctuations and a loss in food quality and color).

* If a food product looks or smells suspect – a damaged seal, swollen lid, off color or texture, for example – discard it without tasting it. Keep it out of the reach of children and pets.

Food preservation can save time and money – and be fun, said Blakeslee, who enjoys preserving summer fruits in homemade jellies and jams to give as holiday gifts.


K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K-State campus, Manhattan.

Story by:
Nancy Peterson
K-State Research& Extension News

Additional Information:
Karen Blakeslee is at 785-532-1673 or