AnswerLine is pleased to welcome Jennie Savits as our newest team member. Jennie joined AnswerLine on June 1 and brings a wealth of knowledge and experience to the team. Further, she is no stranger to Iowa State University or Extension and Outreach.
Jennie holds BS/MS degrees in Food Science from Iowa State University and completed 11 years with the Midwest Grape and Wine Industry Institute at Iowa State University. While with the Institute, Jennie held various roles in the lab and in the field. She worked on extension and outreach activities and research projects to support the local grape and wine industry in Iowa and throughout the Midwest. Jennie also has experience with the Department of Food Science and Human Nutrition at Iowa State University as a lecturer, where she taught food science laboratory courses and oversaw laboratory renovations.
Jennie’s interest in food science stemmed from participation in the 4H and FFA organizations. Growing up in rural Boone County, she was a member of the Harrison Happy Hustlers 4-H club and the Boone A&M FFA Chapter. Jennie enjoyed completing 4H projects in the areas of food and nutrition, horticulture, and livestock. Food science became a key area of interest after she competed on a team that won the inaugural Iowa FFA Food Science Career Development Event (CDE). Their team went on to place 2nd nationally and directed Jennie’s career path toward food science.
Jennie says that she really enjoys the opportunity to help people find answers and solve problems, especially on topics related to food safety and food preservation. Jennie has developed strong relationships within the Iowa State University Extension and Outreach organization and looks forward to helping disseminate research based information to those we serve.
Jennie lives with her husband, Paul, and their 5 children on a farm near Ogden. She enjoys spending time with family, helping out around the farm, and gardening.
I am a graduate of the University of Nebraska-Lincoln with a BS in Home Economics Education and Extension and from Colorado State University with a MS in Textiles and Clothing. I enjoy spending time with family and friends, gardening, quilting, cooking, sewing, and sharing knowledge and experience with others.
America’s favorite juice and jelly grape, the Concord, is ripe now. Extracting a clear juice from grapes or any fruit for a jelly or juice can be a daunting task. A steam juicer makes juicing fruit easy and results in a clear juice ready for making jelly or saving the juice. The prep work is minimal; steam does all the work.
Steam juicers are a four-part stacked cooking unit–a water reservoir bottom pan, a middle collection pan with a funnel opening in the center, a steam basket pan, and a lid. Water is placed in the bottom pan and boiled gently. As it boils, steam funnels up through the hole in the middle pan and heats the fruit in the steam basket pan. The lid prevents the steam from escaping. As the fruit heats, the fruit releases its juice which drips down through the holes in the steam basket and collects in the middle pan. As the collection pan fills, the juice begins to run out of the unit through a silicon tube on the front of the middle collection pan into a heatproof vessel placed below the unit. The juice is clear, free of pulp, and is ready to drink, gel, can, or freeze after it comes out of the steamer. So easy!
The steamer saves so much time and effort. For a step-by-step ‘how to’, see Steam Juicing: Extracting the Juice, ucanr.edu, by UCCE Master Food Preservers of El Dorado County, CA. There is no chance of over steaming the fruit; one just needs to be mindful of keeping sufficient water in the lower pot so that it doesn’t boil dry. Extraction is complete when the fruit has completely collapsed; it is a good idea to let the collapsed fruit sit for awhile after steaming as juice will continue to be released. If there is a need to move on with another batch, the collapsed fruit can be placed in a colander on the counter and allowed to drain while steaming goes on with additional batches.
While many internet sites suggest that the juice can be drained right into hot sterilized canning jars, capped, and left to cool on the counter, this is not a safe practice. To be shelf safe, fruit juices need to be processed in a hot water bath. (See directions: National Center for Home Food Preservation, nchfp.uga.edu/how/can_02/grape_juice.html.) Jelly can be made directly from the extracted juice. The juice may also be frozen for future use. Sugar may be added prior to canning or freezing, if desired.
Just about any type of fruit works with a steam juicer; cherries, plums, apricots, blueberries, cranberries, apples, and pears are just some suggestions. Fruits like apples or pears should be cut in half before steaming while all small fruits can be left whole. Steam juicers can also be used to extract juice from vegetables. When not being used for juicing, the bottom pan makes a great cooking vessel and when combined with the steam basket, it becomes a great steamer for steaming vegetables and other food items or steam blanching vegetables before freezing.
Some fruit and vegetable juices do well to sit for a period before using or preserving to allow any sediment to settle. Grapes, in particular, are prone to tartrate crystal formation. To learn more about preventing tartrate crystals, see Preventing Crystals in Grape Jelly, Jam, Syrup, and Juice, blogs.extension.iastate.edu/answerline/?p=10143.
I am a graduate of the University of Nebraska-Lincoln with a BS in Home Economics Education and Extension and from Colorado State University with a MS in Textiles and Clothing. I enjoy spending time with family and friends, gardening, quilting, cooking, sewing, and sharing knowledge and experience with others.
The last things that anyone wants to find in homemade grape jelly or syrup are granular or crunchy bits or a hard crystal formation at the bottom of a jar of juice or intermingled in jelly. After the effort of foraging wild grapes or picking domestic grapes, juicing the grapes, straining the juice, and making and processing juice, syrup, or jelly/jam, these finds are discouraging. The hard formation or crunch bits are crystals—crystals formed from tartrate acid, sugar, or evaporation.
What Are Tartrate Crystals?
Tartrate crystal formed at the bottom of grape juice. Photo by M Geiger.
Grapes differ from many other fruits in that they contain tartaric acid, a unique, natural compound. When juice is extracted from grapes and cooled, the tartaric acid reacts with potassium, the mineral of highest concentration in most grape juices,1 to form harmless potassium bitartrate crystals, also known as tartrate crystals or tartrates. While the crystals pose no food safety risk, they are certainly unwanted when preparing grape juice, syrup, jams, jellies, and even wine. Tartrates in wine are known as wine diamonds and may appear as salt crystals, glass shards, or fine dust in a bottle or glass of wine—visual defects that the wine industry works hard to prevent.2 Tartaric acid is used in the making of cream of tartar.
Preventing Tartrate Crystals
Regardless of the grape variety or color, preventing tartrates is easy to solve with time and filtering materials.
Begin by extracting the juice from the grapes by traditional methods or a steam canner. Let the freshly extracted juice sit undisturbed overnight or for 24 hours in the refrigerator. Oregon State University Extension suggests two to five days. My personal experience is that longer is better if one has the time and space, as crystals have formed in my juices after sitting overnight and even after 24 hours. When the juice is warm, the tartaric acid is suspended; as the juice cools, the tartaric acid binds with the potassium to form solid crystals that sink to the bottom of the container along with any other sediment.
Remove the juice from the refrigerator, being careful not to disturb the juice. Clarify the juice by pouring the juice into a clean container through cheesecloth, a jelly bag, or a fine strainer before beginning any further preparation. As you near the bottom of the container, avoid pouring the sediment and crystals into the container. The sediment and crystals should be discarded. It is also an option to filter the juice a second time, if desired.
Free of tartrates and sediment, the juice is ready to be used for jelly, syrup, or juice. Recipes for jelly, syrup, and juice can be found at the National Center for Home Food Preservation. The juice can also be frozen to be used later for making jelly or enjoying as juice.
What are Sugar Crystals?
Sugar is made up of tiny sucrose crystals which prefer to remain in their dry, undisturbed crystalline state. Even when sugar is dissolved in liquid, as when making jams and jellies, the sugar molecules like to congregate into groups or crystals. All they need to start the process is a “seed,” such as a lone undissolved sugar crystal as a nucleus to draw other sugar molecules towards it. Sugar crystals are not unique to grape sweet spreads. Regardless of the fruit, the sugar must be completely dissolved with no traces of crystals to provide a “seed” when making sweet spreads or syrups.
Preventing Sugar Crystals
Crystals in sweet spreads may be caused by excessive sugar, undissolved sugar sticking to the sides of the kettle, or a mixture cooked too slowly, too long, or too little.3 To prevent crystals from forming:
Follow the recipe exactly. Do not add or decrease the sugar or double the recipe.
Wipe the side of the pan free of crystals with a damp cloth before filling the jars. This will prevent a seed point from forming.
Cook with a rapid boil. Remove from heat immediately when the jellying point is reached.
Cook until the sugar has completely dissolved and mixed with the fruit juice.
Learn additional tips to prevent crystals from this Penn State Extension video. Sweet spreads exhibiting sugar crystals are safe to eat.
Evaporation Crystals
Crystals that form at the top of a jar of jelly or sweet spread that has been opened and allowed to stand are caused by evaporation of liquid. Over time, these crystals may also work their way down through the spread. This is usually due to long-term refrigeration or a poorly capped jar kept in the refrigerator. Fruit spreads exhibiting evaporation crystals are safe to eat. White, fluffy mold on the surface of a sweet spread is a sign of spoilage and should be discarded.
Sweet spreads that have crystallized due to evaporation can sometimes be saved with a gentle rewarming to melt the crystals, as one might reheat honey that has crystallized. Place the jar in a pan of hot water or carefully microwave until the crystals melt. Stir as needed. If melting is successful, a fresh jar should be used to prevent recrystallization from the crystals that may remain on the walls of the jar. Adding a small amount of lemon juice or corn syrup may also fix it. In all cases, it is usually a temporary fix as the product may crystallize again if not used in a timely manner. A tight-fitting lid is the best prevention.
With just a little patience and careful preparation, crystals of all types can be prevented in grape products.
I am a graduate of the University of Nebraska-Lincoln with a BS in Home Economics Education and Extension and from Colorado State University with a MS in Textiles and Clothing. I enjoy spending time with family and friends, gardening, quilting, cooking, sewing, and sharing knowledge and experience with others.
Tomatoes – peppers – onions – spices! GO! It’s time to make salsa!
Salsa is a great candidate for fresh, frozen, or canned preparations. Any combination of ingredients may be used for fresh or frozen salsa without concern for foodborne illness. Canned salsas, on the other hand, must be made with care to prevent botulism poisoning. Most salsa recipes are a mixture of low-acid foods like onions and peppers and acid foods like tomatoes or fruit. Salsa can only be safely canned in a boiling water bath IF the recipe meets the acidity levels needed to prevent the growth of botulism bacteria.
The following caution about using original salsa recipes is emphasized in the Pacific Northwestern Extension publication, Salsa Recipes for Canning: Because salsas are a mixture of acid and low-acid ingredients, they are an example of an acidified food appropriate for boiling water canning if–and only if–the level of acidity is adequate to prevent the production of the botulism toxin. If the mixture has less acidity, it needs to be treated as a low-acid food, which requires additional laboratory testing to develop the processing recommendations for the elimination of botulism risk. To avoid this serious foodborne illness, follow the directions carefully of tested recipes. Never can salsas that do not follow a tested recipe.
The best way to ensure a safe home-canned salsa is to carefully follow a tested recipe. Below are a few sources for finding a safe canning recipe that suits your taste. A popular recipe is Choice Salsa from the National Center for Home Food Preservation, featuring more flavor from peppers and onions. Links to other recipe sources include:
Corn and black beans are ingredients used in some commercially prepared salsas; currently, there are no research-based recipes for home canned salsas using these ingredients. Add these ingredients and others at the time of use. Tomato-Based Salsas by the University of Minnesota Extension has additional excellent tips for making salsa safely.
While it is important to follow a research-tested recipe, some substitutions or changes can safely be made to tested salsa recipes. Safe substitutions or changes include:
Change tomato variety or color. Any color or variety of tomato can be used. Paste tomatoes such as Roma have firmer flesh and produce thicker salsa than slicing tomatoes. Seeds or juice should not be removed unless the recipe specifies such action. Tomato quantity should not change.
Substitutesweet peppers for hot peppers, and vice versa, measure for measure when preparing home-canned salsa using a tested recipe. The same is true for onions, as red, white, and yellow onions are interchangeable, measure for measure.
Reduce or eliminate the sugar or salt in any tested salsa recipe.
Reduce the amount of low-acid ingredients such as onion, celery, or green peppers in a tested salsa recipe. Do not substitute corn, black beans, or any other low-acid ingredients for an ingredient being reduced.
Substitute tomatillos for tomatoes as long as the total amount remains the same.
Change types and amounts of dried spices and herbs, but do not add extra fresh herbs to recipes.
Replace 5% acidity vinegar with bottled lemon or lime juice but not vice versa.
For safety, you may not:
Add ingredients such as corn or black beans to any salsa recipe, or substitute corn or black beans for other ingredients such as peppers or onions.
Reduce the type or amount of acid, such as lemon or lime juice, or vinegar, in a tested recipe. If it tastes too tart, add a bit of sugar.
Increase the amount of fresh herbs or garlic in a tested salsa recipe. Fresh herbs may be added to the salsa just before serving.
Do not thicken salsa with any thickening agent. If salsa from a tested recipe is thinner than you prefer, strain the salsa before serving or using it as an ingredient.
Freezing is the only safe long-term option for preserving untested or original salsa recipes. A salsa that has been frozen may be watery when thawed. The excess juice may be drained off or thickened with a starch or tomato paste just before serving. Fresh salsas may be kept in the refrigerator for up to 2 weeks. Salsa may only be water-bath canned in pint jars; there are no tested recipes for quarts or for pressure canning.
I am a graduate of the University of Nebraska-Lincoln with a BS in Home Economics Education and Extension and from Colorado State University with a MS in Textiles and Clothing. I enjoy spending time with family and friends, gardening, quilting, cooking, sewing, and sharing knowledge and experience with others.
The dictionary defines ‘conditioning’ as a means to change a behavior or strengthen muscles. In the realm of food preservation safety, ‘conditioning’ is the process used to equalize moisture left in food after dehydrating to decrease the chance of spoilage or mold growth. While conditioning could be used for all dried foods (herbs, vegetables, and fruits), conditioning is most important for fruit including tomatoes.
The moisture content of home dried fruit should be about 20 percent1 or less when removed from the dehydrator or oven. However, due to the size of the pieces, location in the dryer, or uneven drying, the remaining moisture may not be evenly distributed among the pieces. Even drying can be hard to obtain in a home dehydrator and naturally some pieces will likely have more than a 20% moisture. Because there is no sure way to test for moisture at home, conditioning becomes necessary and is the last step before final storage. Conditioning is not necessary if the fruit is dried for immediate snacking rather than storage; dried fruit for snacking should be stored in the fridge and eat within 3-4 days.
Conditioning is easily done following these steps:
Cool foods on trays and test for dryness. Dried fruits should be leathery and pliable when cool. Squeeze a handful of the fruit. If no moisture is left on the hand and pieces spring apart when released, they are dry.2
Place the food into non-porous, food grade containers (glass or clear plastic jars work great) filling about two-thirds full. Seal the container with a lid.
Shake or stir the contents daily for 10-14 days. During this time, the drier pieces will absorb the excess moisture of the less dried pieces.
Check for condensation on the lid or sides of the container or food pieces sticking together. Also, look for signs of spoilage. If condensation is noted, return the food to the dryer for additional drying time followed by another conditioning. If there is any sign of mold, discard the product.
If drying the same food in successive batches, freshly dried fruit may be added to a conditioning batch within the first five days with conditioning time lengthened to accommodate the additional food.3 Conditioning is also recommended for fruit leathers.
What about conditioning vegetables and herbs? It is easier to tell when vegetables and herbs are thoroughly dry. Dried vegetables should be hard and brittle. For more information on individual vegetables, check out Drying Vegetables – 9.308 to help determine dryness. Herbs are dry when they are crisp and crumbly. Conditioning of vegetables and herbs is an option to reduce concern.
Once fruit is conditioned, it is ready for packaging in glass jars, food-grade plastic containers or plastic food-storage bags. The packaging used should provide an airtight seal. An oxygen or moisture absorber may be added but is not necessary. Packaging in smaller amounts is recommended as once the package is opened, quality begins to deteriorate; the food may lose flavor or absorb moisture and odors from the air. Storing in a cool, dry, dark location is best. The same packaging recommendations apply to vegetables and herbs.
So while the dictionary doesn’t define the conditioning of dried foods, perhaps a third definition should be added. Conditioning is an essential step in the safety of dried foods, particularly fruits and tomatoes.
Sources:
1Andress, Elizabeth L and Judy A Harrison. So Easy to Preserve, 6th edition. Page 341. University of Georgia Cooperative Extension.
2Kendall, P and J Sofos. June 2012. Drying Fruit – 9.309. Colorado State University Extension. https://extension.colostate.edu/topic-areas/nutrition-food-safety-health/drying-fruits-9-309/#:~:text=Select%20fresh%2C%20fully%2Dripened%20fruits,in%20a%20cool%2C%20dry%20place.
Kendall, P, P DiPersio, and J Sofos. Drying Vegetables – 9.308. Colorado State University Extension. https://nchfp.uga.edu/how/dry/csu_dry_vegetables.pdf
I am a graduate of the University of Nebraska-Lincoln with a BS in Home Economics Education and Extension and from Colorado State University with a MS in Textiles and Clothing. I enjoy spending time with family and friends, gardening, quilting, cooking, sewing, and sharing knowledge and experience with others.
Fermentation workshops will soon be offered to Iowa residents. Human Science Food and Health Specialists with Iowa State University Extension and Outreach (ISUEO) gathered at Iowa State University for a pilot fermentation workshop lead by Specialist Jill Weber to train and prepare.
Workshop participants shred cabbage. Photo by Jill Weber.
The workshop offered a broad overview of fermentation, potential health benefits of fermented foods, and how to conduct a successful workshop. Using a small-batch method, participants engaged in the making of their own quart jar of sauerkraut to ferment at home.
Consumer interest in home fermentation has grown in recent years with specific interest in fermenting vegetables and kimchi for the beneficial bacteria fermented products may provide for gut health. The biggest trend in fermentation is small-batch fermentation—small amounts made regularly using quart (or larger) jars. Small-batch fermentation goes more quickly and allows one batch to be fermenting while a previous batch is eaten fresh deriving all the benefits of a fresh ferment. The consumer market has responded with an assortment of fermentation kits designed to make fermentation fun and 1-2-3 easy. Small-batch fermentation is an excellent workshop activity for learning and engaging.
To help Iowans safely preserve foods, Iowa State University Extension and Outreach also offers Preserve the Taste of Summer 101 food preservation classes or workshops at various locations throughout the state covering topics such as jams and jellies, salsa, pickles, canning, freezing, and dehydrating. The classes and workshops are helpful for beginning home food preservers as well as experienced preservers who wish to stay current with safe practices.
Food preservation and fermentation workshops are a great way to learn about the science that goes into preparing a safe product. However, the classes and workshops go beyond learning about preservation, fermentation, or making salsa or sauerkraut. Workshops bring people together as they create their own ‘make and take’ product; it is also an opportunity to broaden social and cultural experiences as strangers share in a common adventure that may be new to them.
To find out when a Preserve the Taste of Summer 101 workshop will be offered, check the Preserve the Taste of Summer webpage for class or workshop offerings. Fermentation workshops are planned around the state beginning this fall; to indicate interest in attending a fermentation workshop, email Jill Weber (jweber@iastate.edu) with your name, phone, and county in which you live. Jill will help you find a workshop near you.
I am a graduate of the University of Nebraska-Lincoln with a BS in Home Economics Education and Extension and from Colorado State University with a MS in Textiles and Clothing. I enjoy spending time with family and friends, gardening, quilting, cooking, sewing, and sharing knowledge and experience with others.
Calcium Chloride is a firming agent that can be used in quick-processed pickles for crispness. It works by firming the natural pectin of the vegetable. It should not be confused with table salt, which is sodium chloride.
Currently, calcium chloride is available to consumers as a granular product under the labels of Ball Pickle Crisp® and Mrs. Wages Xtra Crunch®. Regardless of the label, both are pure, certified food-grade calcium chloride. (Non-food-grade calcium chloride should not be used for home canning.) Calcium chloride is a safe, non-toxic food additive that has been tested and approved by the Food and Drug Administration (FDA), World Health Organization (WHO), Canadian Food Inspection Agency, and European Food Safety Authority (EFSA).
Calcium chloride may be used in place of food-grade lime (calcium hydroxide) to firm pickles. However, it does so with less fuss and offers the same great taste and crispness. Firming with lime is traditionally done by soaking fresh cucumbers in a lime-water solution before pickling them; during the soaking, the calcium hydroxide binds with the pectin in the cucumber making it stronger. Excess lime absorbed by the cucumbers must be removed by additional rinsing to make pickles safe; pickling lime raises the pH (more alkaline) and has been linked to botulism. Because calcium chloride does not have the hydroxide component of lime, it does not change the pH (acidity) of pickled food or pose a food safety risk. No soaking and rinsing is involved when calcium chloride is used. Rather, a small amount of the calcium chloride granules is added to each jar of pickles before sealing, following the manufacturer’s directions. (Calcium chloride should not be added to a vat during brining or fermentation of pickles.)
Calcium chloride will not replace the crispness that is lost from fresh produce. That crispness comes from the vegetable’s natural pectin, so starting with fresh-picked, top-quality produce is best.
There are other uses for calcium chloride beyond pickle crispness. It is used by brewers, cheese- and wine-makers and has been found to improve the texture of canned apple slices, pears, and peaches. Consumers report using it when canning whole tomatoes to hold the tomatoes together. Calcium chloride may impart a bit of a salty taste but adds no sodium.
Calcium Chloride products have an indefinite shelf life but are sensitive to moisture and will clump and become hard when exposed to humidity, so it is important to keep the granules as dry as possible; store the products tightly sealed in a cool, dry location.
Reference to any commercial product, process, or service, or the use of any trade, firm, or corporate name is for general informational purposes only and does not constitute an endorsement, recommendation, or certification of any kind. Persons using such products assume responsibility for their use and should make their own assessment of the information and whether it is suitable for their intended use in accordance with current directions of the manufacturer.
I am a graduate of the University of Nebraska-Lincoln with a BS in Home Economics Education and Extension and from Colorado State University with a MS in Textiles and Clothing. I enjoy spending time with family and friends, gardening, quilting, cooking, sewing, and sharing knowledge and experience with others.
Tomatoes can be preserved by freezing, canning, or drying with good results. For best results, remove the skins of all varieties of tomatoes before preserving them.
Removing tomato skin, sometimes called peeling or skinning, means removing the outer covering or skin from a fruit or vegetable, usually with a knife—like peeling an apple or a potato. My grandma said, ‘slip the skin,’ which seems more appropriate for removing the skin from a tomato. The process is simple:
Dip tomatoes in boiling water for 30 to 60 seconds until the skins split or wrinkle.
Dip into cold water, slip off the skins, and remove the cores.
It is recommended that the skin of all varieties of tomatoes be removed before canning, including cherry tomatoes. If you have a lot of tomatoes and time is short, they may be frozen with skins on (or removed). When the tomatoes are thawed, the skins will slip right off. Tomatoes that have been frozen and thawed may be used in place of canned tomatoes in any recipe or canned following a tested recipe.
Removing the skins is important for these reasons:
Most tested recipes for tomato products were prepared and tested with skins removed. Therefore, the processing time is based on a peeled tomato unless stated otherwise. Skins may interfere with the necessary uniform heat penetration in the canning process resulting in underprocessing and an unsafe product.
The skins of fruits and vegetables are sources of bacteria, yeasts, and molds. Some of these contaminants are removed when produce is washed with cool water, but removing it all is impossible. The bacterial load is reduced by peeling or slipping the skins, resulting in a safer final product.
The texture of the skin may be undesirable in the finished product. Tomato skins do not break down well, often leaving chewy bits in the product.
The flavonols in tomato skin impart a bitter taste.
So bite the bullet and slip those tomato skins. While skinning the tomatoes might take time, it is an important step when canning tomatoes. That extra time ensures that the product is safe to consume when the jar is opened and tastes good.
I am a graduate of the University of Nebraska-Lincoln with a BS in Home Economics Education and Extension and from Colorado State University with a MS in Textiles and Clothing. I enjoy spending time with family and friends, gardening, quilting, cooking, sewing, and sharing knowledge and experience with others.
Consumers have unlimited resources for canning recipes—cookbooks, websites, family recipe boxes, friends sharing recipes, magazines, and more. How does one know if the recipe will result in a safe product? Iowa State University Extension and Outreach recommends following scientifically researched and tested home canning recipes to ensure a safe, quality product.
The biggest concern with home canning is the prevention of botulism, a deadly toxin produced by the Clostridium botulinum bacteria, which can thrive in an oxygen-free, vacuum-sealed jar if the product has not been prepared or processed correctly. To avoid the potential of botulism, it is important to determine if the recipe is safe before gathering the ingredients and proceeding.
Considerations to ponder before using a recipe
Generational or Historic Recipe? Home food preservation is an ever-evolving science. While Great Grandma’s recipe may be a family favorite, it may have been developed by trial and error or not meet today’s safety standards. Open kettle canning (heating the food to boiling, pouring it into jars, applying lids, and allowing the heat within the jar to seal the lid) was common practice in bygone years and is no longer recommended. Further, a sealed jar does not indicate that the product is safe if proper techniques have not been used. Oven canning and jar flipping are other unsafe practices of yesteryear. The only safe home canning methods recognized today are processing in a boiling water bath, atmospheric steam canner, or pressure canner for a specified time. When used properly, these methods provide adequate heat to destroy harmful or spoilage organisms and drive air out of the jar for a strong vacuum seal. Using an old cookbook or the recipe book that came with a canner purchased many years ago may also be out of date with current standards. Recipes or instructions before 1994 are considered outdated unless formulations match new research-tested formulations.
Testing Source? Who did the testing? A great deal goes into scientifically testing a recipe; testing should be done in a laboratory where pH (acidity) and processing time/product density are measured and considered. Testing involves measuring the temperature of a product inside the jar with thermocouple sensors to derive a safe product based on the pH and the time it takes to heat the product to the proper temperature throughout the entire jar while still maintaining product quality.
Processing Procedure? Any food placed in a jar to be vacuum-sealed must be processed in a boiling water bath, atmospheric steam canner, or a pressure canner, unless it is dried or to be frozen, to destroy microorganisms that can cause spoilage or illness. It is not acceptable to pour hot jam or pickles into a jar and allow the jar to seal while cooling, open-kettle can, or use paraffin wax as a sealant. High acid foods (most fruits, pickled vegetables, preserves) with a pH of less than 4.6 can be processed in a boiling water bath or atmospheric steam canner because botulism does not grow in an acidic environment. Low acid foods (vegetables, meats, soups) with a pH greater than 4.6 must be processed in a pressure canner to raise the temperature from boiling (212⁰F) to 240-250⁰F to destroy Clostridium botulinum spores that cause botulism.
Starch Additions? Thickeners such as flour, starches, gelatin, pectin and even Clear Jel®, should not be used in canning recipes unless the recipe has been tested for such. Thickeners slow the rate of heat penetration into the product and may result in under processing and an unsafe product. Flours and starches also tend to clump and break down in the canning process; Clear Jel® is an exception and can successfully be used for pie fillings and some jams. Adding more processing time to accommodate the use of added thickeners is unsafe. Thickeners should be added to the product at time of use.
Added Ingredients? It is not safe to add extra ingredients to a recipe; adding beans or corn to a canned salsa recipe is not safe. It is also not safe to add extra vegetables to low-acid products, like extra onions, chilies, or peppers to tomato products or salsas. Additions may decrease the acidity and/or increase the density of the product resulting in an unsafe product. Some safe substitutions or exchanges may be allowed for dietary reasons, preferred taste, or spiciness.
Acidification? Tomatoes are borderline +/-4.6 on the pH scale due to several factors. Therefore, tested recipe sources will specify bottled lemon juice or citric acid use to provide adequate acid levels. The recommended amount is 2 tablespoons of bottled lemon juice or ½ teaspoon citric acid per quart or half the amount for pint jars. Tomatoes that are not acidified could harbor the botulism toxin, whether processed in a boiling water bath, atmospheric steam canner, or pressure canner.
Using current, researched-based recipes from reliable sources is the best advice. The most recent USDA updates to home canning were made in 2015. Additional research has shown that elderberries and white peaches should not be canned due to safety concerns. Recipes from the following sources have been carefully tested in university laboratories. When recipes from these sources are prepared as directed and processed as recommended, the product will be safe and of the highest quality possible.
Choose your recipes prudently. Follow the recipe carefully and adjust for elevation. Preserving food using the most updated research-based methods is imperative for your safety and the safety of those you feed. If you have questions about a recipe or the canning procedure, call or email AnswerLine to receive help from a trained professional.
I am a graduate of the University of Nebraska-Lincoln with a BS in Home Economics Education and Extension and from Colorado State University with a MS in Textiles and Clothing. I enjoy spending time with family and friends, gardening, quilting, cooking, sewing, and sharing knowledge and experience with others.
Canning, pickling, freezing, drying, and fermenting are well-known methods of preserving fruits and vegetables for future use. These processes have been used for generations and made simpler and safer over time with the help of science and innovation. Freeze drying (lyophilization) is a more recent option for home food preservation due to the advent of home freeze dry units. HarvestRight, a company in Salt Lake City, Utah, introduced a freeze drying unit for home use in 2018, opening new opportunities for home food preservation. Early in 2023, a second company, Prep4Life, introduced a slightly different freeze drying unit for home use known as THE CUBE; Prep4Life is also a Utah-based company.
Freeze drying is not a new process. The process may date back to the 13th century, with the Incas using a simple process to preserve potatoes in the Andes. The first patent was issued in 1934. During World War II, it was used to safely transport blood serum and penicillin to the battlefield. In the 1950s–1960s, freeze drying was viewed as a multi-purpose tool for pharmaceuticals and food processing and became a major component of space and military rations. Freeze drying has been widely used in the food industry for some time to extend the shelf-life of food while maintaining quality (think berries in commercial cereals that feature real berries) and offer consumers fast meal prep, emergency preparedness, and portable food. Freeze-dried foods also offer convenience as some foods can be eaten “as is” (except for raw meat, poultry, seafood, and eggs), added directly to recipes, or rehydrated and used as fresh food.
In a nutshell, freeze drying works by dropping the product temperature to <-40F, then reducing the pressure and adding heat to allow the frozen water in the product to change directly to a vapor (sublimate). Per HarvestRight, the process removes 98-99 percent of the moisture in food yet retains 97 percent of the nutrients, natural enzymes, and original flavor and color, making it a superior method for preserving food [1]. Additionally, freeze-dried foods are easy to use; food returns to its original pre-freeze dried state by just adding water. Since nearly all water has been removed, freeze-dried food is light, making it a favorite for camping and backpacking. A 10-pound bag of fresh apples weighs about one pound after freeze drying. Further, freeze dried foods supposedly have a 25-year shelf-life under proper storage conditions.
To date, very little university research has been done on in-home freeze drying; specifically research on how long the food retains quality and nutritive characteristics [3]. Utah State Extension staff has been experimenting with the HarvestRight dryers. In a recent webinar, they stressed that freeze drying produces high quality foods that are safe as long as they are handled properly prior to freeze drying, dried thoroughly, packaged appropriately, and used or prepared correctly once the packaging is opened. It is important to note that freeze drying does not kill bacteria or other microorganisms; they remain viable, but dormant, despite the extreme conditions of freeze drying. Any bacteria or microorganism on raw foods prior to freeze drying will reactivate upon rehydration. Therefore, food items that are traditionally cooked before eating must also be cooked before eating as a freeze-dried food.
Nearly any food item can be freeze dried—fruits, vegetables, herbs, meats (cooked and raw), eggs, dairy, meals, casseroles, desserts. Utah State recommends that vegetables be blanched prior to freeze drying to prevent discoloration. Food high in fat content, high in sugar content, and baked goods such as breads, cakes, muffins, etc do not freeze dry well and should be avoided. Sugar causes foods to expand.
To ensure the safety and quality of freeze-dried foods, basic food safety principles must be used in preparation, product must be completely dried (crisp), and product must be stored properly. Proper packaging is crucial to extend the shelf life of freeze-dried foods and prevent contamination or spoilage. The storage container must eliminate oxygen, light, and moisture. In order of long-term to short-term storage, the following containers may be used: Mylar® bags, vacuum-sealed canning jars, #10 cans, vacuum sealed bags, and PETE re-sealable containers. An oxygen absorber must be enclosed in the container to remove or decrease the available oxygen in the package to help maintain product safety, quality, and extend shelf life. Foods should be stored in a cool, dark place.
For long-term storage, PET or PETE (Polyethylene terephthalate) food grade, non-toxic plastic pouches, also known as “mylar bags” are excellent. The opaque (silver) Mylar® bags are preferred; they block out air and light during storage, can be resealed once opened and take up less space than glass jars or cans. Mylar® bags with a clear side are not long-term air tight [3]. Mason canning jars can be used if they are vacuum sealed with a vacuum sealing machine capable of using a jar sealing device. Metal cans have a zero oxygen transfer rate and are great for long-term storage [4]. However, a #10 can contains a large amount of dried food which must be used at the time of opening or resealed in another container. Vacuum bags and re-sealable containers have short-term oxygen barrier qualities.
Oxygen absorbers do not have a long shelf life; as soon as they are exposed to air (oxygen), they start to absorb and are spent when they become hard. They are available in different sizes (measured in cc’s); contents and container size should be considered when purchasing absorbers. The smaller the container the less cc’s needed. There is no harm in using a larger than needed absorber and would be preferred to one that is too small [3]. When a container is opened, the absorber should be replaced before resealing.
A freeze dryer is not a fancy food dehydrator. While a freeze drying unit and a dehydrator both remove moisture from food so that microorganisms cannot grow and enzyme action is slowed down, a dehydrator uses low heat and a fan to remove 80-90 percent of the moisture content from food[5]. While dehydration is a very acceptable means of food preservation, it differs from freeze drying in several ways: – foods shrink up and develop a leathery feel and appearance; – foods do not return to their natural state; – foods retain less of their nutritional value; – foods have a 4 months to 1 year shelf life; – fewer foods are successfully dehydrated; – foods rehydrate slowly.
There are many advantages to freeze drying. Besides holding nutritive value, it allows one to utilize garden produce at the peak of harvest, buy in bulk, save money over commercially prepared freeze-dried foods, offers a long shelf life, preserve foods that cannot be typically preserved, and offers compact, lightweight storage. Some disadvantages pointed out by Utah State Extension include unit size, noise, time for drying and allowing freezer to unthaw, cleaning, sanitation, and maintenance, small batch sizes, and cost—cost of the machine as well as machine accessories, packaging supplies, sealers [10], and electricity. In addition, reconstituting freeze-dried foods is somewhat experimental. Utah State Extension specialists suggest starting with a small amount of water and giving ample time to reabsorb; there is no need to rehydrate herbs, onions, or bell peppers as they can be added directly to foods and will absorb moisture from the food. Buying a Home Freeze-Dryer: What to Know Before You Goand Let’s Preserve: Freeze Dryingoffer more information.
The options for food preservation are many.Each method offers pros and cons to preservation and storage. If long-term food storage or portable food storage is the goal, freeze-drying is an option to consider. HarvestRight machines are available at several retail outlets. The Cube is available from the Prep4Life company. Imagine rehydrating lasagna on a camping trip!
Schmutz, Andrea and Callie Ward. 2 May 2023. Freeze Drying. Utah State University. Preserve the Harvest Webinar.
Reference to any commercial product, process, or service, or the use of any trade, firm, or corporate name is for general informational purposes only and does not constitute an endorsement, recommendation, or certification of any kind. Persons using such products assume responsibility for their use and should make their own assessment of the information and whether it is suitable for their intended use in accordance with current directions of the manufacturer.
I am a graduate of the University of Nebraska-Lincoln with a BS in Home Economics Education and Extension and from Colorado State University with a MS in Textiles and Clothing. I enjoy spending time with family and friends, gardening, quilting, cooking, sewing, and sharing knowledge and experience with others.
