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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 collected only at the break of winter and spring when the sap moves intensively. Birch sap collection is done by drilling a hole into its 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.
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 are considered far less tolerant to the wounds caused by tapping, and so more conservative harvesting practises have been recommended by trade bodies such as the Alaska Birch Syrupmakers Association. 
Ancient Slavs and Finno-Ugrics worshipped several Pagan gods. One of the most sacred trees was the birch. Birch sap is a traditional beverage in the Russian Federation (Russian: берёзовый сок, translit. byeryozovyi sok) as well as Latvia (Latvian: bērzu sula), Estonia (Estonian: kasemahl), Finland (Finnish: mahla), Lithuania (Lithuanian: beržo sula, beržų sula), Belarus (Belarusian: бярозавы сок, translit. biarozavy sok, Byarozavik), Poland (Polish: sok z brzozy, oskoła), Ukraine (Ukrainian: березовий сік, translit. berezovyi sik), France, Scotland, Norway, Sweden and elsewhere in Northern Europe as well as parts of Northern China as well as 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. The United States has a few companies that sell Birch sap, but only one company that is 100% organic.
|Nutritional value per 100 g (3.5 oz)|
|Energy||4.6 kcal (19 kJ)|
|Dietary fiber||0 g|
less than 0.1 g
|†Percentages are roughly approximated using US recommendations for adults.|
Birch sap contains heterosides (betuloside and monotropitoside), 17 amino acids including glutamic acid, as well as minerals, enzymes, proteins, betulinic acid and betulin, antioxidants, sugar (fructose, glucose and small amounts of sucrose) and vitamins (C and B(group)). Contrary to popular belief, there is no xylitol in birch sap (xylitol is a sugar alcohol that is industrially produced using high temperature and sulfuric acid, or through fermentation). 
Nutritional and medicinal uses
|Region||Medicinal use||Cosmetic use|
|Belarus||lung diseases, gout|
|Czech Republic||poor health, infertility||against freckles|
|Estonia||(prevention of) eye diseases, skin diseases, source for vitamins||washing hair, against freckles and to bleach the skin|
|Hungary||stomach and lung diseases||against freckles|
|Poland||“revitalization”, kidney stones||washing hair in order to strengthen it|
|Romania||kidney stones, jaundice, as milk-rennet, scab, diuretic||hair colouring, to remove sunspots and moles|
|Russia||externally against sores, to help children during teething||washing face|
|Ukraine||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
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 to 5–7 days. Shelf life can be prolonged by freezing or preservation techniques. Existing preservation techniques:
- Nothing i.e. bottled fresh sap (shelf life: 2–5 days refrigerated)
- Filtered with a 0,22μ net (shelf life: 3 weeks refrigerated)
- Collected under anaerobic conditions (shelf life: 1 year ambient)
- Added sugar (3g per 100ml)
- Heat pasteurized; pasteurization should be conducted under specific temperature levels and time spans (shelf life: 1 year ambient). Although level of Vitamin C is lower than fresh saps', all other benefits are preserved.
- Frozen at -25C (shelflife: 2 years)
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.
|Wikimedia Commons has media related to Birch sap.|
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- Övre Dalarnes bondekultur 3, Lars Levander, Lund, 1947.
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- 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.
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- Nicole & Olivier Lhomme, NICOLL-Nature, Le Bio Logis, La sève de bouleau
- Alaska Birch syrupmakers association Petition to US Food and Drug Administration for establishment of Standard of Identity for birch syrup, including the Alaska Birch Syrupmakers' Association Best Practices. July 18, 2005.