Birch sap


Birch sap, birch water or birch juice is the sap directly tapped from birch trees, Betula alba, Betula pendula, Betula lenta, Betula papyrifera, and Betula fontinalis.
Birch sap may be consumed both fresh and naturally fermented. When fresh, it is a clear and uncoloured liquid, often slightly sweet with a slightly silky texture. After two to three days, the sap starts fermenting and the taste becomes more acidic.
Birch sap is a traditional beverage in boreal and hemiboreal regions of the Northern Hemisphere as well as parts of northern China.

Harvest

Birch sap is collected only at the break of winter and spring when the sap moves intensively. Birch sap collection is done by drilling a hole into the tree trunk and leading the sap into a container via some conduit ; the sap will flow along it because of the surface tension. The wound is then plugged to minimise infection.
Birch sap has to be collected in early spring before any green leaves have appeared, as in late spring, it becomes bitter. The collection period is only about a month per year. No published evidence exists to quantify the long-term impacts of sap harvest on birch tree and birch forest health, or birch timber quality. However, the wounds caused by tapping birches consistently lead to dark staining in the wood. In one study, infection and wood decay had spread from more than half of old tapping holes. In comparison to maples, birch trees are considered far less tolerant to the wounds caused by tapping, so more conservative harvesting practises have been recommended by trade bodies such as the Alaska Birch Syrupmakers Association.

Traditional regions

Ancient Balts, Slavs and Finno-Ugrics regarded birch as one of their most sacred trees. Birch sap is a traditional beverage in Russia, as well as Belarus, Bulgaria, Estonia, Finland, Latvia, Lithuania, Poland, Ukraine, France, Scotland, Norway, Sweden and elsewhere in Northern Europe as well as parts of northern China and both Hokkaido and Aomori as parts of northern Japan. It is also widely used among the Pennsylvania Dutch, either as a traditional beverage in its own right, but particularly as a key ingredient in birch beer.

Composition

Birch sap contains heterosides, 17 amino acids including glutamic acid, as well as minerals, enzymes, proteins, betulinic acid and betulin, antioxidants, sugar and vitamins. Contrary to popular belief, there is no xylitol in birch sap.

Nutritional and medicinal uses

Folk uses

Folk uses include medicinal use, supplementary nutrition, and cosmetic applications for skin and hair.
RegionMedicinal useCosmetic use
Belaruslung diseases, gout, sicknesswashing hair
Bulgariahair growth
Czech Republicpoor health, infertilityagainst freckles
Estonia eye diseases, skin diseases, source for vitaminswashing hair, against freckles and to bleach the skin
Hungarystomach and lung diseasesagainst freckles
Latvia“revitalization”washing hair
Poland“revitalization”, kidney stoneswashing hair in order to strengthen it
Romaniakidney stones, jaundice, as milk-rennet, scab, diuretichair colouring, to remove sunspots and moles
Russiaexternally against sores, to help children during teethingwashing face
Swedenscurvy, cholera
Ukrainetreating skin diseases, source of vitamins, diureticagainst freckles
United Kingdomtonic, rheumatism, first nourishment for new-born childrenprevention of baldness
United StatesPoor health

Commercial birch sap and derivative products

Birch sap may be consumed both fresh and naturally fermented. Fresh birch sap is highly perishable; even if refrigerated, it is stable for only up 7 days. Shelf life can be prolonged by freezing or preservation techniques. Existing preservation techniques include:
Birch sap can also be used as an ingredient in food or drinks, such as birch beer or wintergreen-flavored candy.
Concentrated birch sap is used to make birch syrup, a very expensive type of syrup mainly made from paper birch in Alaska and Canada, and from several species in Latvia, Russia, Belarus, and Ukraine.