Elderberry bushes are native to North America, and they are also a popular home landscaping shrub, with plants readily available at nurseries. Elderberries have a long history of medicinal use in various cultures, and many people make elderberry preserves, fruit leathers and other tart treats. However, elderberry products may be unsafe if prepared improperly. Here’s what to know about elderberries and how to safely preserve them.
Researchers have found that many varieties of elderberries contain toxic compounds called cyanogenic glycosides. People consuming improperly prepared elderberry products have been poisoned. Because raw elderberry products may contain elevated levels of toxic compounds, you should always cook elderberries before eating them.
Preservation instructions also vary by type of elderberry, depending on the acid content of the fruit. There are four major types of elderberries. Some species have a pH above 4.6, which makes them unsafe for water bath canning except in specifically formulated, high-sugar recipes. You can safely preserve all varieties by freezing or drying, but you always need to cook them before consuming to reduce the level of toxic compounds.
Types of elderberries
Blue elderberry (Sambucus nigra ssp. cerulea)
Blue elderberries are native to the western United States and can be found in the wild as well as in home gardens. Ripe blue elderberries are a dusky blue with a powdery appearance that distinguishes them from other elderberry varieties. All available data indicates that blue elderberries are high in acid, with a pH of less than 4.6. These berries can safely be processed using recipes for any other high-acid berry, such as blackberries, blueberries, or strawberries. Blue elderberries are safe to can as juices, syrups and fruit spreads using standard canning recipes. They can also be frozen or dried.
American elderberry (Sambucus nigra ssp. canadensis)
American elderberries are native to the eastern United States. They have been domesticated, and many different cultivars are available at nurseries. Cultivar names include Alesso, Bob Gordon, Golden, Johns, York, Netzer, Norma, Nova, Samdel and Scotia. Goldbeere is a variety of American elderberries that is greenish yellow when fully ripe. The American elderberry plant is shrublike and can grow up to 10 feet high. The berries are a dark purple, and they lack the powdery coating distinctive to the blue variety.
Research in both Oregon and Missouri has shown American elderberries vary in acid content and are not consistently below 4.6, so they are considered a low-acid food. These berries are safe to freeze and dehydrate, but they should not be canned using standard recipes for high-acid berries. Researchers have published one safe recipe for canning that uses a high sugar ratio to achieve a safe product (see below).
European elderberry (Sambucus nigra ssp. nigra)
This subspecies of elderberry is native to Europe but has also been domesticated and is available in the U.S. The European black elder is a small tree up to 20 feet high. Cultivars include Haschberg and Korsor. The berries of this variety are dark purple, like the American elderberry. Limited published data available on European elderberries indicates that these are high acid. Since European elderberries are difficult to distinguish from American elderberries, follow recommended recipes for American elderberries using high-sugar ratios when canning (see below). European elderberries are safe to freeze and dehydrate.
Harvesting
To harvest the flowers of elderberry shrubs, pick whole clusters (cymes) when they are white and open. Place the clusters on a piece of parchment paper and dry at a low temperature (80ºF or less) to preserve the best flavor. Remove the flowers by rubbing them in a bowl, being careful to discard any stray pieces of leaf or stem, which contain higher levels of toxins.
Harvest elderberries when the fruits are fully ripe. Ripe berries have a deep, rich color or, in the case of blue elderberries, a waxy bloom. Not all berries on the plant will ripen at the same time, so you may have to harvest multiple times.
Elderberries spoil quickly. Harvest them during the cooler part of the day and process the fruit as soon as possible. Refrigerate berries at 35–40ºF for short-term storage or freeze them if you cannot process your harvest immediately.
Stems and leaves contain higher levels of toxins, so it is important to remove these before processing. Hand-picking the berries off the stems can be tedious and time-consuming.
One fast way to separate the berries is by “screening.” Place a wire cooling rack over a baking pan and gently rub the berries over the rack. The berries will drop from the stems into the pan below. It can help to freeze the berries before screening.
Preserving elderberries
Elderberries can be preserved in several ways, but not all varieties of elderberries can be used in all canning recipes because of differences in their acid content. Blue elderberries are naturally higher in acid and can be preserved using standard recipes for high-acid berries and fruits. Because blue elderberries are naturally low in pectin, adding regular or low sugar pectin is recommended. American and European elderberries are not high in acid, and you must use only specific high-sugar ratio recipes for water bath canning these berries. If unsure of the type of elderberries, use only the high sugar ratio recipes or freeze or dehydrate for preservation.
Freezing and drying elderberries
Caution: All varieties of raw elderberries should be cooked before consuming.
Elderberries can safely be frozen and dried raw but must be cooked before being consumed to prevent risk of cyanide poisoning. The cooked elderberry pulp can be dried and made into fruit leather. Elderberries are very tart, so they are often combined with a sweeter fruit such as peaches and apples to make into leathers. You can also freeze elderberry juice and syrups for long-term storage.
Acknowledgments
The authors would like to thank Jill Bushakra, Ph.D., and the USDA National Clonal Germplasm Repository for allowing us to collect berry samples from their collection, as well as the OSU North Willamette Research and Extension Center for allowing us to harvest blue elderberries. Lastly, the authors are grateful to Sam Kilgore of Oregon State University for harvesting and transporting samples.
References
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