PICKLES AND FERMENTED PRODUCT SAFETY The acidity (pH) of a food is of great significance in determining the type of processing required for safe preservation of a food. In the case of pickled products, the foods preserved are often low-acid foods (cucumbers, zucchini), but their acidity is adjusted to bring the pH into the high-acid range so that may be safely preserved using boiling water bath processing. The most commonly used acid for pickling is vinegar, however some pickle products are produced by encouraging the growth of microorganisms which produce lactic acid from the naturally-occurring carbohydrates in fruits and vegetables. The lactic acid selects for another group of microorganisms which produce acetic acid that gives pickle products their flavor and helps to lower the pH into the range where these vegetables can be safely water bath canned. The acidity of pickling solutions needs to be maintained below pH 4.5 if water bath canning is to be used. For this reason, the amount and strength of the vinegar is critical. I. Types of Pickles A. Brined or fermented: Depends on selection of natural microorganisms which will produce acid. Selection is accomplished by using salt to inhibit unwanted microbes. Fermentation is usually for 3 weeks or more. Color changes from bright green to olive or yellow green and white interior becomes translucent. Examples: sour pickles, sauerkraut. B. Refrigerator dills: are fermented for one week. C. Fresh-pack or quick-process pickles: Cured for several hours or combined immediately with hot vinegar, spices and seasonings. Examples: pickled beets, bread and butter pickles. D. Fruit pickles: Whole or sliced fruit simmered in a spicy, sweet-sour syrup. Examples: spiced peaches, crabapples. E. Relishes: Made from chopped fruits or vegetables which are cooked to desired consistency in a spicy vinegar solution. Examples: horseradish, corn relish. F. Pasteurized Pickles: Prepared pickles are placed in a canner half-filled with warm (120-140 F) water. Add hot water to 1" over jar lids. The water is then heated to 180-185 F and maintained there or 30 minutes. Temperatures over 185 F may cause softening of pickles. USE THIS PROCEDURE ONLY WHEN THE USDA CANNING GUIDELINE RECIPES ARE USED. II. Ingredients A. Vegetables or fruits for pickling 1. Fruits and vegetables should be ripe but firm, and in good condition with no evidence of microbial or insect damage. 2. Cucumbers should have a 1/16" slice removed and discarded from the blossom end. 3. Use unwaxed cucumbers for pickling so brine will penetrate. 4. Discard any cucumbers which "float"--they can make hollow pickles (use for relish). 5. Prepare fruits and vegetables within 24 h of harvest. 6. Cucumbers: need 14 lb for 7 quart canner load, 9 lb per 9 pint canner load. One bushel weighs 48 lb and yields 16-24 quarts (2 lb / quart). Use 1 1/2" for gherkins and 4" for dills. B. Vinegar 1. Vinegar needs to be of sufficient strength to assure that low-acid vegetables will be appropriately acid. The vinegar should be 5 to 6% acetic acid (50 to 60 grain), and should not be diluted except according to an approved recipe. 2. White vinegar is preferred with light colored fruits or vegetables. 3. Do not use homemade vinegar--there is no way to know the strength (% acetic acid). C. Salt 1. Canning or pickling salt should be used--it contains no iodine (which can cause darkening) or anti-caking ingredients (sodium silicate or tricalcium phosphate) (which cause cloudiness of the brine). 2. Salt inhibits certain kinds of microorganisms and in fermented pickle products, it is required to prevent growth of spoilage and pathogenic microorganisms. Salt also draws water out of the cells making the pickled product more firm. Too much salt will cause shriveling. 3. Do not use "sour salt"--it is citric acid and does not have the same inhibitory effect on microbes. 4. Do not use reduced-sodium salt in fermented pickle recipes. Reduced sodium pickles can be made using quick pickle recipes given in the USDA Canning Guidelines. Fresh pack pickles, acidified with vinegar can be prepared with little salt but the flavor and texture will be affected. 5. Salt concentration in brined, fermented products must not be reduced for safety. Do not try to make sauerkraut or fermented pickles by cutting down on the salt. D. Sugar Either white or brown granulated sugar can be used. E. Spices 1. Use fresh, whole spices in cheesecloth bag. 2. Powdered spices cause darkening and clouding. F. Hard Water 1. Hard water minerals may interfere with acid formation and curing in fermented pickles. In addition, hard water may have a pH of 8.0 or higher. 2. Softening hard water: boil water for 15 minutes then allow to stand for 24 hours. Skim off any scum that appears. Pour out of container so sediment is not disturbed. G. "Crisping Agents" These products are not recommended as they may result in a product with a pH which is unsafe. 1. Lime (calcium hydroxide) which is sold as "slakelime", "hydrated lime", "builders lime", or "household lime". When called for in a recipe, it is added to the brine before pickles are soaked. When used, lime is added for 12-24 hours of soaking. It must be removed from pickles by soaking (1 hour) and rinsing three times in fresh water in order to make the pickles safe. The component of calcium hydroxide which firms up the pickles is the calcium--it cross-links the pectins making them insoluble. DO NOT USE: agricultural lime, burnt lime, quick lime--these are not food grade products and are unsafe. 2. Alum (aluminum and potassium sulfates): Use no more than 1/4 tsp of alum per quart of pickling solution. Excess will cause bitterness. Alum may be safely used--it does not improve the firmness of quick-process pickles. 3. Grape leaves: contain substances which inhibit enzymes that make pickles soft. Blossom removal takes care of this problem. 4. Hot process: pickle firmness may be improved by processing the pickles for 30 minutes in water maintained at 180 F. Water must not fall below 180 F--prevents spoilage (pasteurization). Prepared by Susan Brewer Foods and Nutrition Specialist Revised, 1992 EHE-696