McDonald pointed to statistics from the Centers for Disease Control and Prevention, stating that home-canned vegetables are the most common cause of botulism outbreaks in the United States. From 1996 to 2014, there were 210 outbreaks of foodborne botulism reported to the CDC. Of the 145 outbreaks that were caused by home-prepared foods, 43 outbreaks, or 30 percent, were from home-canned vegetables.
The CDC reports that these outbreaks often occurred because home canners did not follow canning instructions, did not use pressure canners, ignored signs of food spoilage, or did not know they could get botulism from improperly preserved vegetables.
"Failure to use correct methods of processing and preserving food can lead to foodborne illness, with botulism being of greatest concern as shown by the CDC," McDonald said. "Techniques and recipes passed down from generation to generation might not align with modern-day food safety knowledge, and it takes just one misstep to lead to dire consequences. At Penn State Extension, we want to help consumers have a safe experience."
For those new to home food preservation, there are three primary methods: freezing, drying and canning. Of the three, freezing is the easiest, safest and most used, McDonald said.
"If you are just dabbling in home food preservation, you can start by freezing food, especially if you already have a freezer,” she said. "It requires less investment of time in preparing the food and is a great way for beginners to learn the basics of food preservation."
Vegetables and meats are the food products most commonly frozen. McDonald said there are some foods that are not good for freezing due to their high-water content, such as celery, lettuce, cabbage, cucumbers and watermelon.
McDonald explained that there are four factors responsible for most of the quality losses when it comes to frozen foods — enzymes, air, large ice crystals and evaporation of moisture. To prevent these issues, McDonald advises people to inactivate enzymes that cause color and flavor loss over time, to freeze foods as quickly as possible and to use packaging materials specifically recommended for freezing.
These storage materials — which should be moisture-vapor resistant, leak-proof and easy-to-seal — can include flexible freezer bags or wraps and rigid containers. She also suggested placing labels on the items noting the content and date frozen.
Another tip — and this applies to all methods of preserving food — is to make sure foods are thoroughly washed prior to processing, and keep raw meats separate from other foods during preparation to prevent cross-contamination.
Detailed information about freezing techniques can be found at extension.psu.edu/lets-preserve-freezing-vegetables.
Drying foods is gaining popularity too, McDonald said. While there are times one can use an oven to dry foods, many people prefer to use a food dehydrator, an investment that can range from $30 to $200, depending on the size and features available.
Herbs are perhaps the easiest foods to dry, followed by fruits and vegetables such as apples, pears, peaches, plums, apricots, bananas, cantaloupe, strawberries, blueberries, carrots, celery, corn, green beans, potatoes and tomatoes. Meats can be dried as jerky.
Drying inhibits the growth of bacteria, yeasts and molds through the removal of water. However, if too much moisture remains, the food will become moldy. Conversely, overly dried foods can be too hard to eat and can lack flavor. To avoid these problems, McDonald suggests following tips provided at extension.psu.edu/lets-preserve-drying-fruits-and-vegetables.
Finally, there is canning, which is the more labor-intensive way to preserve foods. While most people are familiar with home-canned offerings such as tomatoes, jelly and jams, and pickles, some might not be aware that meats also are canned. In home canning, food is heated or processed in a mason jar at a specific temperature for a certain amount of time to destroy microorganisms, resulting in a vacuum-sealed container that can be safely stored at room temperature.
"Some might think of canning as an art because of pretty jars on the shelf, but there is actually a lot of science behind producing a quality and safe product," McDonald said.
She strongly advises beginners to take a workshop — based on the current USDA recommendations on canning — either in-person or via online videos before making the investment in necessary equipment, which can include canning jars and lids, utensils, water bath canners, and pressure canners. She also recommends using recipes that have been vetted by food scientists.