People often ask about canning pickle recipes that have been handed down from one generation to another. The question usually is, "Are these old pickle recipes safe?"
First, it helps to understand how pickles are made and processed. There are two basic methods of making pickles.
Brined or Fermented Pickles
In the first method, the vegetables go through a curing process in a salt and water brine solution for one or more weeks. Lactic acid produced during this fermentation process helps preserve the product. Once fermentation is complete, these foods must be refrigerated or canned for safekeeping.
Quick Process Pickles
The second method of making pickles is called fresh-pack or quick-process pickles. Raw vegetables or fruit are covered with a boiling hot vinegar-water solution, spices, and seasonings. In fresh-pack or quick-pickles, the big concern is that sufficient acid be present to prevent growth of harmful pathogens. Cider or white vinegar of 5 percent acidity (50 grain) is recommended for pickling.
Often older pickle recipes will call for less vinegar than water. This is a potential safety problem because enough acid must be present to prevent growth of dangerous pathogens.
In the past, vinegar was sold as 7 percent acetic acid. Commercial vinegar is now 5 percent acetic acid. Old recipes developed for stronger vinegar might not contain sufficient acid when used with today's 5 percent vinegar.
It’s important when making pickled products that you use newer recipes with tested proportions of ingredients. Do not alter vinegar, food or water in the recipe or use vinegar of unknown acidity.
Another often asked question about pickling is, "For generations my family has made top quality pickles without using a boiling water process to can them. Why have recommendations changed?”
The recommendation to processing pickles in a boiling water canner was made over 30 years ago. Pasteurization in a boiling-water process destroys yeasts, molds and bacteria that may cause the product to spoil. The water bath process also inactivates enzymes that could affect the color, flavor and texture of the pickle or relish. In addition, a strong vacuum seal is formed so that pickles won't mold. Processing in a boiling-water canner also extends the shelf-life of the product.
Link to Quick Process Pickles for more information and tested recipes.