Evaluating Home Canning Recipes For Safety What do you do when someone gives you "Aunt Tillie's Special" old favorite jam recipe? Or Uncle Willie's barbecue sauce? Or Cousin Millie's dill pickle recipe? In today's heightened awareness of food safety, how do you tell which are safe and which are not? There are no hard and fast rules, or secret formulas, to help you decide. But there are some priorities you can use to help you balance the pros and cons. They depend on the factors that molds, yeasts and bacteria need to grow, and on the relative hazards that molds, yeast and bacteria present in foods. Factors Influencing Safety In food preservation, the growth factors that are important are: Sugar - enough sugar will stop the growth of most organisms Salt - enough salt will stop the growth of most organisms Acid -enough acid will stop the growth of most organisms ** Too little sugar, salt or acid will permit spoilage. Air - most organisms must have air to grow, BUT the most dangerous bacteria in home food preservation, Clostridium botulinum, will only grow without air. Temperature - most dangerous microorganisms grow best at room temperature or a little above. But in preserving food, we are interested in killing the organisms and their spores, not just in slowing their growth. The death rate of microorganisms depends on: The microorganism - they die at different rates The number of cells or spores present initially in the food - the more there are, the longer it will take to kill them all The medium (food) that they are in - most die faster in acidic food than low acid food, and in wet food than dry food. The temperature - in canning the important temperature is the temperature at the coldest spot in the jar. The length of time at that temperature - when we heat food, not all the organisms will die at the same time, they die gradually, and the full process time is necessary to be sure that all, even the most heat-resistant ones, have died. These last two factors, temperature and time, depend on how much solid vs. liquid is in the jar, and on how tightly the food is packed. Heat from the steam or water in the canner penetrates into different foods at different rates. Liquids circulate in the jar and carry the heat into the center of the jar. Solids must heat slowly from the outside in. A process time for randomly packed green beans, which have spaces for water to circulate, will not be adequate for "tin soldier" green beans, when the tightly packed, vertically aligned beans leave no room for water to circulate. The most important microorganism in home canning is Clostridium botulinum. The toxins it produces damage the nervous system, producing paralysis and possible death. The damage to nerve cells is permanent. Minute amounts of contaminated food can carry enough toxin to cause death. This bacteria produces spores which are very resistant to heat. It is also very sensitive to acid, and will not grow in acid foods. Other pathogenic bacteria are usually killed by much less heat and in a shorter period of time than Cl. botulinum. Most require air, so will not grow in a sealed jar. They are of less concern in home canning. Molds and yeast are of concern because if they grow they can reduce the amount of acid present in the food. If that occurs Cl. botulinum may be able to grow. Some molds, particularly those that grow on fruits and fruit products are known to produce toxins that cause damage to the nervous system and kidneys, or cancer in research animals. The likelihood is that they will cause some damage in humans if consumed often enough. (Toxin-producing molds grow well on grains and peanuts, but these products are not home-canned.) Molds and yeasts will also spoil the taste, texture, color and overall appearance of the food, making it unfit for consumption. Jams, Jellies, Sweet Spreads In a jam or jelly recipe made with regular pectin, not the low or no-sugar variety: If the jam or jelly sets properly (stiffens into jam or jelly) it has enough sugar to inhibit the growth of bacteria and all but a few sugar-tolerant molds and yeasts. This will also be true for marmalades and preserves, and for jellies made the long-boil method without added pectin. The fruit blend used is not crucial. However, mold growing on a fruit spread is a problem. It should not be scooped off, rather the entire product should be discarded. To avoid mold problems, all jellies, jams and sweet preserves should be packed in pre-sterilized jars and processed 5 minutes or more in a boiling water bath canner. The exceptions are some of the sugar-free types which explicitly state on the package of jelling agent that they should not be processed. These contain preservatives to prevent mold growth, and the heat of processing would cause soft jelly. In addition, heat will cause the sweetener to break down and lose its sweet taste. Pickles and Relishes The pickle recipe is more complicated. The proportion of acid (vinegar) to the amount vegetable is crucial. Enough vinegar must be added to change the low-acid cucumber into a high-acid pickle to be safe. There is no formula or set proportion to decide if the recipe provides for adequate vinegar. The best thing to do is to find a recipe with similar procedures in the USDA Guide to Home Canning and compare the amounts. This is especially true of pickle relishes or vegetable relishes where several vegetables are ground together. Similarities to look for include: 1. Similar recipes will use the same presoak - soak in ice water, or in salt water, or no soak. 2. They will call for the same size cucumbers - 4", or 6", or 8", or specify small or large. 3. The maturity of the cucumber influences how much acid it will take to pickle it. Smaller, less mature cucumbers have the capacity to neutralize more acid per unit of weight than do larger, more mature ones. 4. Similar recipes will also specify similar procedures with the brine: Are the slices or spears packed in the jar raw and the brine poured over, are they merely heated in the brine, or are they simmered before packing? Is the simmering or boiling time the same? Each of these will influence how rapidly the acid penetrates the cucumber and how much the cucumber juice will dilute the acid. 5. Similar recipes will call for similar proportions of onion or other vegetables. 6. Quantities of salt are critical in fermented pickled products; proportion of salt to vegetable to vinegar should be very similar to USDA recipe to be sure that it will be safe. Proportions of spices are not crucial and may be adjusted to suit tastes without danger. If too little salt is used the cucumbers will spoil, get slimy, float, smell foul, and the fermenting mixture may support the growth of hazardous microorganisms. If too much salt is used, there will be no fermentation, just shriveled cucumbers sitting in salt water. Either case is obvious: the recipe is not good. In quick pack pickles the amount of salt is not critical. Salt may be omitted, or a reduced sodium salt-type product used. The flavor and texture may be noticeably different, and probably less acceptable but, the product will be safe. All pickle products should be processed in a boiling water bath to reduce the likelihood of mold or yeast spoilage. Old recipes for whole or sliced pickles that have been used for generations without processing and without spoilage should at least be given a 10 minute process. Pickle relish products must also adhere to the USDA proportions and process times. Quantities of vegetable and vinegar, heating prior to packing, and process time must be similar to a USDA recipe. An old, tested and trusted recipe may be used if the 10 minute process time is used. Other recipes may be changed, or the product refrigerated. For comparison of quantities, note the following equivalencies: 1 lb 5" cucumbers = about 5 cucumbers 1 lb mushrooms = about 6 cups chopped = 1 1/2 cups sauteed 1 lb onions = about 3 cups chopped = about 4 medium 1 lb green peppers = about 3 C chopped = 8-9 peppers 1 lb sweet red peppers = about 3 cups chopped = 6-7 peppers 1 lb celery = about 4 cups chopped) 1 lb tomatoes = about 3 medium = about 1 1/2 cups chopped 22-23 lb tomatoes = about 7 quart or 28 cups cooked juice Other Ingredients: The use of alum is unnecessary. The slight increase in crispness that it provides is lost after about 2 months of storage. Few pickles are consumed within 2 months of processing. However, since alum is usually used in very small amounts, its use does not constitute a safety problem. The use of grape leaves might contribute slightly to flavor. They have no significant effect on safety. Lime does cause a significant increase in the crispness of pickles. If it is used, all excess lime must be rinsed away before the vinegar is added since it will neutralize the vinegar. After the soak in lime water, the cucumber slices should be soaked in fresh water then drained, re-soaked and drained two more times (3 rinses in fresh water). Honey may be used safely, but quantities will need to be adjusted for taste, and color may be darker. One cup of sugar is equivalent to 3/4 C + 1 T honey (or 1 C less 3 T). Tomato Products Tomatoes and tomato products are very hard to categorize. Tomatoes are borderline acidic. Lemon juice or other acid (vinegar, citric or ascorbic acid) must be added to all tomato products to insure adequate acidity. Added acid is necessary whether the product will be pressure canned or boiling water bath processed. Bacteria and spores die faster in an acidic environment, and the recommended process times for pressure canning assume that the tomatoes are acidic. The times would not be reliably adequate to insure safety if the tomatoes were low-acid. Green tomatoes are more acidic, and may be used safely in any recipe calling for red tomatoes. Overripe and frosted tomatoes are less acidic and can not be safely home canned. They can be frozen. Addition of salt, while optional, does give an extra margin of safety. For dietary information, one teaspoon of salt added to 1 quart of juice or sauce adds about 526 mg sodium per cup. Addition of low-acid vegetables to tomatoes decreases the acidity. The amount by which the acidity is lowered depends on which vegetables, how much, how finely they are chopped, if they are boiled in the tomatoes or not, if seeds and skins remain in or are removed, and if the chunks of vegetable and tomato remain, if they are ground together or sieved out. The initial acidity of the vegetables and tomatoes depends on maturity, growing conditions, post-harvest holding conditions, and soil/location of growth. It is impossible to test every recipe. It has so far been impossible to develop a set of proportions or an equation that would take into account all the variables and give a reliable assessment of the acidity or the necessary process times. The only safe recommendations can be made by comparing the recipe in question with the USDA guide recipes. If more vegetable or less acid (vinegar or lemon juice) is added than the USDA recipe, the recipe in question can be changed or the product should be processed according to the process times for the vegetables. Alternatively the product may be frozen or refrigerated. These proportions of vegetables have processing times in the USDA Home Canning Guide: Tomato-vegetable juice 22 lb tomato : 3 C chopped vegetable Spaghetti sauce 30 lb tomato : 8 C vegetable : no acid Ketchup #1 24 lb tomato : 3 C onion : 3 C vinegar Ketchup #2 24 lb tomato : 1 C peppers : 2.6 C vinegar Ketchup #3 24 lb tomato : 9 C vegetables : 9 C vinegar Use the equivalencies above to convert the amount of vegetables to cups before a recipe is evaluated for safety. The tomato-vegetable juice recipe specifies "chopped vegetables". Up to but no more than 3 cups of mixed vegetables may be safely added to tomatoes to make 7 qts of juice. Which vegetables are used is not important, the margin of safety is large enough to tolerate the variations in this recipe. BUT, after boiling, this recipe is pressed or sieved, so the chunks are removed, and a smooth juice is canned. These proportions can not be used for a chunky sauce. The spaghetti sauce is pressure processed, so the proportions can be different. The tomato acid and the long boiling prior to canning are sufficient. These proportions and procedures can be used with different spices to make a taco or barbecue sauce type products. Ketchups 1 and 2 are pressed or sieved so skins and seeds are removed. The proportions are similar, #2 with less added vegetable has a little less added vinegar. Ketchup #3 is a blender ketchup, skins are not removed prior to canning. The amount of added vegetable and of added acid is much greater relative to the amount of tomato. If these proportions are maintained, the amounts of sugar and spices may be varied to suit one's taste without endangering the safety of the product, and processing times given in the USDA Guide can be used. If other proportions are used, if the product is canned chunky instead of sieved smooth, or blended raw (uncooked) or any other variation, the processing times are not valid: the recipe must be changed, or the product must be frozen or held refrigerated. Fruits and Vegetables These products may be safely canned only according to USDA guidelines. Piece size, packing density and process times must be followed. Grated carrots can not be safely processed according to times for carrot chunks. Pumpkin puree can not be safely canned. The density varies too much, according to variety and preparation method, to give safe recommendations. Only pumpkin chunks may be canned. Addition of aspirin, salt, or "canning powders" will not increase the safety or allow for reduced process times. Deviations from the specified procedures might not be safe. The only safe recommendations that can be given for other procedures is to freeze or refrigerate the product. Fruits and vegetables may be pickled. In this case the guidelines for pickled products should be used. Jar Sizes For all products, if the USDA Home Canning guide only offers processing times for pint jars, then the product should not be canned in quarts. Usually this occurs for dense or tightly packed products such as cream style corn, or for heat-sensitive products such as jelly, mushrooms or pickle relishes. In all cases, the extra processing time that would be required to insure an adequate temperature for an adequate time in the coldest part of the jar would be so long that the quality of the product would be lost. Relishes would be soft and mushy, corn would be tough, jelly would be syrupy. Packing food for canning in irregularly-shaped jars such as ketchup bottles or honey bears is not acceptable. The irregular shape and size might not allow for normal circulation and heat penetration, and cold spots might exist that would allow for the survival of bacteria. If the product has all ready been packed and processed within the last 24 hrs, it may be repacked and reprocessed in smaller jars, or refrigerated. If it has been longer than 24 hrs since the processing, the product should be discarded to ensure safety. Food may be packed and processed in smaller jars, half pint instead of pint if desired, but the processing time to be used should be that specified for pints. There is no formula to determine how much less processing would still be adequate. Mayonnaise or other straight sided, regularly shaped, commercial packer jars may be used for boiling water bath canning only. They should not be used for pressure canning, due to the danger of breakage, particularly when the canner is opened. Flying glass is dangerous. SUMMARY 1. SWEET FRUIT SPREADS If it was made with regular pectin, high sugar recipe: Did it jell? If it jelled, it has enough sugar, so is safe. Was it processed? If not processed, it should be refrigerated for added safety. Is there visible mold? If so, discard the entire contents of the container. If it was made with a low sugar or no sugar pectin product: Were the directions on the box, particularly the processing or refrigeration, followed exactly? If the directions were not followed, but there is no visible spoilage, the product may be refrigerated, or possible frozen. If there is mold, if there are bubbles rising, or other signs of spoilage, the product must be discarded. 2. PICKLED VEGETABLE OR FRUIT: Find a recipe that has similar ingredients and procedures, ie. presoak, size of pieces, maturity and size of vegetables, treatment in brine. If there is no similar recipe, you can make no judgement on the recipe. If it is an old recipe that has been used successfully for generations without spoilage, a 10 minute processing should be added. If there is a similar recipe, compare the amount of acid to vegetable between the two. If the recipe in question has less acid, either the acid can be increased or vegetable decreased to fit the USDA recipe. If acid is increased, sugar may be increased to adjust the flavor. If the product is all ready made and the recipe is unsafe: If it was made less than 24 hrs previously, it may be refrigerated. If it was made more than 24 hrs previously, it should be disposed of in a safe manner. If the recipe is safe but the product was not processed: If it was made less than 24 hrs previously, it may be processed, with new lids. If it is cold, either empty the jars, heat product, repack, and put into hot water, or put cold, filled jars in cold water, heat together; process for full time. It may be refrigerated, or frozen if feasible. If it was made more than 24 hr previously, and has not been refrigerated, it should be disposed of in a safe manner. 3. TOMATO-VEGETABLE BLEND: Find a similar recipe in the USDA Guide. Check ingredients, proportions, and procedures. If there is no similar recipe, no processing times can be estimated. To err on the side of safety, do not using the recipe, or freeze the product. If there is a similar recipe, check proportions of tomato to vegetable, and be sure there is added lemon juice or vinegar. Minor adjustments to quantities of ingredients may be made to fit the USDA recipe. USDA recipes for juice can not be used to judge chunky sauce recipes, or vice versa. Spices and seasonings are not crucial to the safety of a recipe and can be adjusted. 4. FRUIT OR VEGETABLE: Only USDA procedures and processing times may be considered safe. Products improperly processed less than 24 hours previously may be reprocessed, with new lids, or refrigerated or frozen. Products improperly processed more than 24 hrs previously should be discarded as potentially unsafe. 5. Wrong JAR OR JAR SIZE: If a larger jar or an irregularly shaped jar was used, and the food was processed less than 24 hours previously, it may be reprocessed, with new lids, in smaller jars. If more than 24 hours have passed, the food should be discarded. Prepared by Mary A. Keith, Foods and Nutrition, September, 1991 Revised by M. Susan Brewer, Foods and Nutrition, June, 1992 EHE - 705