Canning processes are determined for specific foods prepared by specific directions for a particular size of jar. The process time is determined based on the length of time it takes to adequately heat the coldest spot in the jar. The way the food is prepared (such as the size of pieces, with or without the peel, etc.), the consistency of the canning liquid and the size of the jar have an effect on how heat penetrates through the product.
It is important to follow directions exactly. If you add sugar or fat or if you don’t prepare the food according to the directions, or if you add thickeners like starch, rice or noodles, then the process time tested as being accurate to heat even the cold spot in the jar may not be safe.
Besides selecting the appropriate method of canning, there are certain other rules you must follow to have safely canned products. If the directions say to peel and chop, then peel and chop. If they say to leave whole, then leave whole. If it says process 30 minutes for pint jars, then put it in pint jars and process not 20, not 25, but 30 minutes!
If pressure canning in a dial gauge canner, your gauge must be tested and accurate. Donna Krug and Berny Unruh, Extension Educators at the Cottonwood Extension offices in Great Bend and Hays are happy to provide pressure gauge testing free of charge. Simply bring your lid (you do not need to remove the gauge) to either office, 1800 12th Street in Great Bend, or 601 Main Street, in Hays and we will be happy to test your gauge. We can only test the brands National, Presto, Maid of Honor, and Magic Seal.
Only use recipes and directions from reputable sources such as USDA, Extension, the National Center for Home Food Preservation, the Ball Blue Book or So Easy to Preserve book published by The University of Georgia. K-State’s Rapid Response Center website is a great place to find recipes: https://www.rrc.k-state.edu/preservation/recipes.html
Some people insist on using a salsa recipe that has not been tested or approved for home canning– maybe an old family recipe or one they created themselves. When the acidity level is unknown, the recipe cannot be guaranteed to be safe. To can homemade salsa in a water bath or a pressure canner, follow instructions available in the KSU publication MF1185 “Preserving Tomatoes.” Many people call and ask for the Fiesta Salsa recipe from this publication.
I have had several people ask what can be done with tomatoes when they freeze. Do not can tomatoes from frost-killed or dead vines. Their pH may be higher than 4.6. But you can eat or freeze them for later use.
Also, when canning, you cannot rush the process. Heat up and cool down times are a part of the process so don’t try to cool the canner down quickly by setting it under cold, running water. Be patient and let it cool down in its own time.
Check out Karen Blakeslee’s videos that are short and to the point on the Rapid Response Center website: https://www.rrc.k-state.edu/preservation/videos.html
Berny Unruh is the Family and Community Wellness Agent for the Cottonwood Extension District. She can be reached at 785-628-9430 or at firstname.lastname@example.org.