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[1] 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 (a tube or simply a thin twig); the sap will flow along it because of the surface tension. The wound is then plugged to minimise infection.[2]
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.[2] However, the wounds caused by tapping birches consistently lead to dark staining in the wood.[2] In one study, infection and wood decay had spread from more than half of old tapping holes.[2]
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.[2]
Traditional regions
Ancient Balts, Slavs and Finns regarded birch as one of their most sacred trees[3][4] and made a traditional beverage from it.
It is also widely used among the Pennsylvania Dutch, both as a traditional beverage in its own right, and particularly as a key ingredient in birch beer.[7]
treating skin diseases, source of vitamins, diuretic
against freckles
United Kingdom
tonic, rheumatism, first nourishment for new-born children
prevention of baldness
United States
Poor health
Commercial birch sap and derivative products
Bottle of Russian commercial birch sap
Birch sap may be consumed both fresh and naturally fermented. Fresh birch sap is highly perishable; even if refrigerated, it is stable for only 7 days. Shelf life can be prolonged by freezing or preservation techniques. Existing preservation techniques include:[18]
Nothing i.e. bottled fresh sap (shelf life: 2–5 days refrigerated)
Filtered with a 0.22-μ net (shelf life: 3 weeks refrigerated)
Collected under anaerobic conditions (shelf life: 1 year ambient)
Heat pasteurized, pasteurization should be conducted under specific temperature levels and times (shelf life: 1 year ambient). Although level of Vitamin C is lower than in fresh sap, all other benefits are preserved.
Frozen at −25 °C (shelf life: 2 years)
Birch sap can also be used as an ingredient in food or drink recipes,[19] such as birch beer or wintergreen-flavored candy.
^National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Food and Nutrition Board; Committee to Review the Dietary Reference Intakes for Sodium and Potassium (2019). "Chapter 4: Potassium: Dietary Reference Intakes for Adequacy". In Oria, Maria; Harrison, Meghan; Stallings, Virginia A. (eds.). Dietary Reference Intakes for Sodium and Potassium. The National Academies Collection: Reports funded by National Institutes of Health. Washington, DC: National Academies Press (US). pp. 120–121. doi:10.17226/25353. ISBN978-0-309-48834-1. PMID30844154. Retrieved 2024-12-05.
^Sosa, A (1935). "Un glucoside nouveau de Betula Alba L. Le bétuloside et son aglycone, le bétuligénol". Paris Masson ed.
^Ahtonen, S; Kallio, H (1989). "Identification and seasonal variation of amino acids in birch sap used for syrup production". Food Chemistry. 33 (2): 125–132. doi:10.1016/0308-8146(89)90115-5.
^Kallio, H; Ahtonen, S (1985). "Identification of the Sugars and Acids in Birch Sap". Journal of Food Science. 50 (1): 266–269. doi:10.1111/j.1365-2621.1985.tb13328.x.
