Category: Food Safety

Safe Food Storage Containers

Marlene Geiger
Vegetables stored in glass storage containers

Safe storage practices are just as important as knowing how to safely prepare, serve, or preserve food. Most kitchens contain an assortment of containers, wraps, and bags for storing food either short- or long term. These items may be glass, plastic, silicone or metal. How do we know if a container is appropriate and safe for storing our foods?

To begin, all food products should be stored in food-grade containers. Food-grade is a regulatory term used to specify materials and products that are suitable and safe to come into contact with food and beverages at any point in the field-to-consumer chain. To be certified as a food-grade, food-safe material, the material undergoes extensive testing to insure that the material does not affect the color, odor, taste, or safety of the food or leach substances into the food. The Food and Drug Administration (FDA) is the regulatory agency responsible for determining the safety of materials for food use. It is important to note that a food-grade material is only considered food-safe if it is utilized per its intended use.

Safe Food-Grade Container Options

Glass, stainless steel, and ceramic – These materials are non-reactive and non-toxic. They are easily sanitized and offer the most longevity. These materials are sturdy and heat-tolerant and do not release chemicals or toxins into food. Further, they are inert and do not react with natural chemicals or dyes found in food. Food and beverages stored in these containers stay fresh longer. Glass and ceramic can be microwaved; all three can be heated in the oven and placed into the dishwasher. These materials are eco-friendly; glass is especially so being 100% recyclable. Some cons of these materials include weight, breakability (glass and ceramic), cost, bulk, and lack of portability. 

Plastic – There are many reasons to use plastics: inexpensive, lightweight, hard to break, stackable, and readily available. While there are many plastic choices, one must choose wisely. Experts caution us against using plastics in general, and in particular older plastics, or re-using one-time-use plastics from purchased foods. Although plastic containers are convenient, many may contain BPA (Bisphenol A), a chemical that blocks and interferes with hormones leading to health issues. BPA is a big concern in older plastics or plastics that are scratched or heated in the microwave.

Any plastic used should be microwave safe, dishwasher safe, and BPA-free. Plastic products are typically labeled with a number surrounded by the recycling symbol. These numbers and labels identify both the type of resin used to make the plastic and the product’s recyclability. Associated with the different types of resin are potential health risks. The Smart Plastics Guide provided by the Public Broadcasting System (PBS) summarizes seven different types of commonly used plastics, product examples, recyclability, and potential health risks.

Safe plastic numbers include 2, 4, and 5. These containers can store food without any toxic chemical infiltration and include the HDPE, LDPE, and PP materials. Containers with the number 7 are made of polycarbonate (the category that includes BPA), so should not be used with food. Plastics bearing numbers 1, 3, and 6 are single-use-only containers or bottles.

So what about those easy-to-pick-up plastic containers available at retailers or our long-held Tupperware®? Check to make sure they are labeled with one of the safe plastic numbers, BPA-free, and dishwasher and microwave safe. According to its website, Tupperware® items sold in the US and Canada have been BPA-free since March 2010; containers prior to 2010 should be disposed of as should any other older containers that do not display numbers 2, 4, or 5, contain BPA, and are not dishwasher and microwave safe.  

Since plastic does not have the longevity of glass or stainless steel, food safety experts encourage swapping out plastic containers frequently and especially if there is any discoloration, odor, or a change in taste when using the container. When plastic containers become scratched, stained, or damaged, they begin to pose a food safety risk by harboring bacteria and other harmful microorganisms that can contaminate food.

Silicone – Per the FDA, food grade silicone is safe and will not react with other materials or release hazardous compounds or fumes when heated. Food-grade silicone is safe to store food, put in the microwave, freezer, oven, and dishwasher without hardening, cracking, peeling, or becoming brittle as it is resistant to extreme temperatures. It is made without petroleum-based chemicals, BPA, BPS, PVC, latex, lead, phthalates, or fillers. It will not leak, break down, or degrade over time.  Silicone containers are available in many forms, lightweight, easy to transport, and considered a non-hazardous waste.

Cautions with silicone storage containers include limited studies on the long-term health effects of using silicone products as they are fairly new to the market. And while silicone is not a hazardous waste, it can only be recycled at special recycling centers.

All containers should provide a secure, air-tight seal.

As we strive to provide fresh, flavorful, and safe food for our families, it is important to store our food properly. Make choosing an appropriate food-grade storage container a priority to keep your food safe and fresh in the pantry, freezer, or refrigerator.

Sources:

Marlene Geiger

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.

More Posts

Consumer Management, Equipment, Food Safety , , , ,
Leave a Comment on Safe Food Storage Containers

Welcome Jennie Savits to AnswerLine!

Marlene Geiger 2 Comments

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.

Marlene Geiger

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.

More Posts

Adult Learning, Child Development, Cleaning, Consumer Management, Food Preparation, Food Preservation, Food Safety
2 Comments on Welcome Jennie Savits to AnswerLine!

Preventing Crystals in Grape Jelly, Jam, Syrup, and Juice

Marlene Geiger 2 Comments
jars of grape jelly and grapes

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.
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, 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. 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. 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.

References

Marlene Geiger

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.

More Posts

Food Preservation, Food Safety , , , ,
2 Comments on Preventing Crystals in Grape Jelly, Jam, Syrup, and Juice

It’s Salsa Time!

Marlene Geiger 5 Comments

Tomatoes – peppers – onions – spices! GO! It’s time to make salsa! 

jars of home canned 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.
  • Substitute sweet 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. Frozen salsa containers should be opened upon removal from the freezer to create an aerobic (with oxygen) environment to deter the potential growth of Clostridium botulinum.  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.

Additional sources

Marlene Geiger

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.

More Posts

Food Preservation, Food Safety , , ,
5 Comments on It’s Salsa Time!

Conditioning Dried Foods

Marlene Geiger

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:

  1. 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
  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.
  3. 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.
  4. 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:

Marlene Geiger

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.

More Posts

Food Preservation, Food Safety , ,
Leave a Comment on Conditioning Dried Foods

Calcium Chloride for Crispness

Marlene Geiger

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.

Sources:

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.

Marlene Geiger

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.

More Posts

Food Preservation, Food Safety , ,
Leave a Comment on Calcium Chloride for Crispness

Peel Tomatoes Before Preserving

Marlene Geiger 8 Comments

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: 

  1. Dip tomatoes in boiling water for 30 to 60 seconds until the skins split or wrinkle.
  2. 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.

For more information on freezing, canning, and drying tomatoes, check out How to Preserve Tomatoes and Preserve the Taste of Summer, Canning and Freezing Tomatoes. When canning tomatoes or tomato products, remember to acidify with commercially bottled lemon juice or citric acid to prevent the possibility of botulism.

Updated 8 June 2023.

Sources:

Marlene Geiger

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.

More Posts

Food Preservation, Food Safety , , ,
8 Comments on Peel Tomatoes Before Preserving

Preserving by Home Freeze Drying

Marlene Geiger

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 Go and Let’s Preserve:  Freeze Drying offer 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!

Sources:

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.

Marlene Geiger

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.

More Posts

Equipment, Food Preservation, Food Safety, Food Science
Leave a Comment on Preserving by Home Freeze Drying

Canning Season Readiness – Time to Test Pressure Canner Dial Gauges and Check Out the Canner

Marlene Geiger

A pressure canner is the only safe method for canning low acid foods—red meats, seafood, poultry, and low acid vegetables.  Ensuring your pressure canner is working properly and in good condition is critical to producing unquestionably safe products every year.

Two pressure canners, one with dial gauge (rear) and one with a weighted gauge (front). Canner in front shows a cutaway to inside the canner. Image source: National Center for Home Food Preservation.

Dial Gauges Must be Tested Annually for Accuracy

Most of today’s pressure canners have either a dial gauge or weighted gauge for indicating and regulating the pressure.  There is one exception; the All American brand has both a dial and weighted gauge. For canners having a dial gauge, safe canning beings with getting the gauge checked for accuracy yearly or before the start of the canning season.  A dial gauge has movable parts which can go out of calibration. Gauges that read high cause under-processing and may result in unsafe food.  Clostridium botulinum bacteria are the main reason why low-acid foods must be processed with the correct pressure and time to be safe.  Gauges with low readings may cause over-processing which is not a food safety issue, but rather a food quality issue.  Pressure adjustments can be made if the gauge reads 2 pounds high or low.  Gauges testing more than 2 pounds of difference, should be replaced. The dial gauge should also be checked if any of the following conditions exist: cover has been submerged in water or dropped, gauge lens is broken or has fallen out, parts are rusty, pointer is not on “0”, or for any reason you believe the gauge may not be accurate. The dial should be replaced if it is cracked, rusted, or the glass is missing.  Gauges on new canners and replacement gauges should be tested before use.

Weighted gauges do not require testing for accuracy because they cannot go out of calibration.

Dial Gauge Testing Services

There are several services that provide dial gauge testing.

Local County Extension Office – Many County Extension Offices have the equipment and trained personal for testing the National (National Pressure Cooker Company), Magic Seal (sold by Montgomery Ward), Maid of Honor (sold by Sears, Roebuck and Company), or Presto® brands. Check with you local office for availability or to find out about testing events in your area. AnswerLine (800-262-3804 or 515-296-5883) can help residents of Iowa and Minnesota find a location for testing in your area.

Presto – National Presto Industries will test dial gauges at no charge provided it is one of the following brands: National (National Pressure Cooker Company), Magic Seal (sold by Montgomery Ward), Maid of Honor (sold by Sears, Roebuck and Company), or Presto®. Check out the Care and Maintenance Guide at Go.Presto.com for information on how to send a gauge for testing.

Hardware Stores – some hardware stores also offer this service. Call before you go.

All-American – For testing of All-American dial pressure gauges, contact Wisconsin Aluminum Foundry, 920-682-8627. The weight is more accurate than the gauge and customers should use the weights to attain the correct pressure. If the weight begins to rock at the desired pressure and the gauge is off by more than 2 psi the company recommends replacing the gauge. The gauge is primarily used as a reference to know when the unit is at 0 psi and can safely be removed and the canner opened.

Canner Manufacturers – For pressure canner brands not aforementioned, contact the manufacturer of the unit.

After testing is complete, you will get a Canner Dial Gauge Testing Report or similar. It is a good idea to keep the reports for reference.

In addition to getting dial gauges checked, there are a number of other items to check out to make sure that the canner is in good working order for canning season.  If any of the following do not check out, they should be replaced or cleaned as needed.

Replacement Parts

Replacement parts are available at some hardware stores or stores that also sell food preservation equipment.  Parts may are also be purchased directly from some of the manufacturers. The Pressure Cooker Outlet has replacement parts for many makes and models of canners. Parts can also be found at Amazon.com. Be sure to know the canner model number and part number of the needed item (may be found in the canner manual). The model number can be found on the bottom of the canner, the handle, or the lid. 

Start the canning season off right. Get the gauge tested and make sure that your canner meets all check marks. 

Sources:

Marlene Geiger

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.

More Posts

Consumer Management, Equipment, Food Preservation, Food Safety , , ,
Leave a Comment on Canning Season Readiness – Time to Test Pressure Canner Dial Gauges and Check Out the Canner

Safe Frosting for Iowa 4-H Fairs

Marlene Geiger 5 Comments

The recently released Foods for Iowa 4-H Fairs – Quick Reference Guide (2023) lists “traditional vanilla buttercream made with butter, powdered sugar, extract, and milk” as an acceptable homemade frosting for baked goods exhibited or displayed at Iowa 4-H fairs. Identifying a safe “traditional buttercream frosting” recipe for exhibit has been a source of confusion for 4-H members and their families as well as County Extension Educators and fair judges. Store-bought, commercially prepared frostings that are shelf stable are acceptable for food product exhibits. 

Food products exhibited at 4-H Fairs must be shelf stable or stable (non-perishable) at room temperature and not require refrigeration to be safe. Due to the various ingredients and quantities that may be incorporated into a homemade frosting, many frostings require refrigeration to be unquestionably safe. Three factors play a role in determining the safety of a frosting: acidity (pH), water activity (Aw), and percent of soluble solids (%Brix).

The acidity (pH) of a frosting is affected by the ingredients used. Traditional frostings made with dairy or eggs tend to increase pH making them more basic than acidic and susceptible to spoilage. Therefore, frosting made with cream cheese, whipped cream, or eggs requires refrigeration to inhibit spoilage and molding despite the fact that frostings are laden with sugar, known for its ability to inhibit microbial growth.  

Water activity (Aw) is the measure of available water in a food product that can support microbial growth and affect the quality and safety of food. This differs from moisture content which refers to water bound to ingredients within the food. The FDA has established that a water activity (Aw) value greater than 0.85 on a scale of 0 (bone dry) – 1.0 (pure water) indicates a high-risk food product capable of facilitating the growth of microorganisms in the product. Sugar may lower the Aw while water or dairy can increase the Aw; fat has no effect on Aw. 

Percent soluble solids (%Brix) in a frosting is determined by the amount of sugar available to bind up the available water to reduce bacterial growth. As %Brix increases, Aw decreases.

Due to these factors, frostings are considered TCS, foods that require either temperature or time control for food safety. TCS foods may allow pathogens to grow and possibly produce toxins when held at temperatures between 41-135 degrees F. (For additional information see: Food Safety of Frostings and Fillings by K-State Research and Extension.) To be considered a non-TCS food, the percent soluble solids (%Brix) must be above 65% and the Aw value less than 0.85.1

There are numerous recipes for buttercream frosting. It is not a given that all buttercream frostings meet the %Brix and Aw requirements to be a non-TCS food or safe without refrigeration. To determine the safety of a vanilla buttercream frosting for Iowa 4-H exhibits, three members of the AnswerLine team prepared an adapted version of the Simple Buttercream Frosting tested and considered stable at room temperature by K-State Research and Extension. Milk (dairy) was substituted for heavy cream in the K-State recipe. The frostings were prepared at the individual homes of the team members using the same butter and powdered sugar; the percent of milk fat and vanilla extract were the two variables. The three samples were submitted to the Iowa State University Food Quality and Safety Laboratory for analysis of water activity and %Brix with results shown in the table below.

Table 1.  Average water activity and % soluble solids of frostings tested.

SampleWater Activity% Soluble Solids
Sample 1 – Skim milk0.788± 0.00368.60 ± 0.30
Sample 2 – 2% Milk0.812 ± 0.00467.83 ± 0.23
Sample 3 – Whole Milk0.808 ± 0.00667.17 ± 0.35

All three samples met the requirements of a non-TCS food as recommended by K-State Research and Extension exhibiting an average Brix of 67.87% and an Aw value of 0.803.

Tested Vanilla Buttercream recipe ingredients. Photo credit: Rachel Sweeney

Tested Vanilla Buttercream Recipe
 Required for use with Iowa 4-H Fair Food Product Exhibits.
(All Iowa 4-Hers must reference and attach this blog to their
write-up for full credit if a homemade frosting is used in the exhibit. Any change or addition of ingredients will be unacceptable and will result in disqualification.)

1 cup unsalted butter, slightly softened
4 cups powdered sugar
¼ teaspoon salt
1 teaspoon vanilla extract
2 Tablespoons dairy milk (skim, 2%, or whole)

Beat the butter, salt, and vanilla together until fully combined on medium speed. Reduce speed and add the powdered sugar and milk. Add the milk a teaspoon at a time to achieve the right consistency for the way you want to use the frosting. DO NOT use more than 2 tablespoons of milk.  Slowly increase the speed of the mixer and beat until the frosting is light and fluffy. 

What Does This Mean for Iowa 4-H Food Products?

  • It is highly suggested that exhibits be presented without frosting unless the frosting is part of the exhibit goal.

Example 1:  My goal is to bake an angel food cake for exhibit at the fair.
No frosting is needed for this exhibit. Cake recipe should be included with the exhibit.

Example 2*: My goal is to bake and frost a chocolate cake for my Dad’s birthday. I will also exhibit a similar cake and frosting at the fair.
Cake should be frosted with the tested vanilla buttercream frosting or with a commercially prepared frosting to assure that it is not a TCS food. No chocolate, cocoa, or other ingredient should be added to the tested recipe or commercial frosting. Recipe for cake and frosting (if homemade) should be included with the exhibit, along with this blog. 

Example 3*: My goal is to learn to make a cake and a frosting for exhibit at the fair.
Cake should be frosted with the tested vanilla buttercream frosting; no chocolate, cocoa, or other ingredient should be added to the tested recipe. Cake and frosting recipes, along with this blog, should be included with exhibit. 

*For examples 2 and 3, another option is to prepare the product using any frosting desired; before serving, take pictures of the frosted product. Exhibit the product without frosting at the fair and note in the write up that the product is being exhibited without frosting due to food safety concerns. Add pictures of the frosted product to the write up and include the product recipe with the exhibit.

  • Homemade Cream Cheese, German Chocolate or Coconut-Pecan, Ganache, or 7-Minute frostings or fillings are not to be exhibited at the fair. They are potential TCS foods due to the range of water activity (Aw) in various recipes and should be stored in the refrigerator.
  • Decorator frostings of any type may be used when the goal is to decorate a cake. The cake may be food, cardboard, or Styrofoam and will be judged on design, neatness, originality, skill, and technique; the cake will not be tasted or judged on product characteristics. 
  • Fresh or canned fruit, vegetable, or zest should not be used as decoration or garnish on a baked product or decorated cake.
  • When a glaze is desired, it should be made with powdered sugar and water only. No fruit juice or zest should be added.

Plan ahead for a successful fair experience. 4-H members are encouraged to call or email AnswerLine with questions about their food project prior to exhibit. 

Call:  1-800-262-3804 or 515-296-5883, M-F 9-12, 1-4
Relay Iowa (hearing impaired) 1-800-735-2942
Email:  answer@iastate.edu

_________________________________
Food Safety of Frostings and Fillings – MF3544, K-State Research and Extension

By Shannon Coleman, Associate Professor and State Extension Specialist, Department of Food Science and Human Nutrition, Iowa State University; Terri Boylston, Associate Professor, Department of Food Science and Human Nutrition, Iowa State University; Marlene Geiger, Beth Marrs, and Rachel Sweeney, Consumer Specialists AnswerLine, Iowa State University Extension and Outreach;  Karen Blakeslee, Extension Associate, Kansas State University Research and Extension.  February 2023.

Marlene Geiger

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.

More Posts

Child Development, Food Preparation, Food Safety , , ,
5 Comments on Safe Frosting for Iowa 4-H Fairs

AnswerLine

Connect with us!

AnswerLine's Facebook page AnswerLine's Pinterest page
Email: answer@iastate.edu
Phone: (Monday-Friday, 9 am-noon; 1-4 pm)
1-800-262-3804 (in Iowa)
1-800-854-1678 (in Minnesota)

Archives

Categories

Meta