Birch sap

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Extraction of birch sap

Birch sap, birch water or birch juice is the sap directly tapped from birch trees, Betula alba (white birch), Betula pendula (silver birch), 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[1] as well as parts of northern China.

Harvest[edit]

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[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[3]. However the wounds caused by tapping birches consistently lead to dark staining in the wood[4]. In one study, infection and wood decay had spread from more than half of old tapping holes[5]. 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. [6]

Traditional regions[edit]

Ancient Slavs and Finno-Ugrics worshipped several Pagan gods. One of the most sacred trees was the birch.[7][8] 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[9], Sweden[10] and elsewhere in Northern Europe[1] 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.[11] The United States has a few companies that sell Birch sap, but only one company that is 100% organic.[citation needed]

Composition[edit]

Sap, birch water[12]
Nutritional value per 100 g (3.5 oz)
Energy4.6 kcal (19 kJ)
1.1 g
Sugars1.1 g
Dietary fiber0 g
less than 0.1 g
MineralsQuantity %DV
Calcium
6%
60 mg
Iron
1%
0.1 mg
Magnesium
3%
11 mg
Manganese
52%
1.1 mg
Phosphorus
1%
6.4 mg
Potassium
3%
120 mg
Percentages are roughly approximated using US recommendations for adults.

Birch sap contains heterosides (betuloside and monotropitoside),[13] 17 amino acids including glutamic acid,[14] as well as minerals, enzymes, proteins, betulinic acid and betulin,[15][16][17] antioxidants,[18] sugar (fructose, glucose and small amounts of sucrose) and vitamins (C and B(group)).[18] 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). [19]

Nutritional and medicinal uses[edit]

Folk uses[edit]

Folk uses vary from medicinal use, supplementary nutrition (minerals and vitamins) and cosmetic applications for skin and hair.[1]

Region Medicinal use Cosmetic use
Belarus lung diseases, gout
Bulgaria hair growth
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
Latvia “revitalization” washing hair
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
Sweden scurvy, cholera
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[edit]

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 up to 5–7 days. Shelf life can be prolonged by freezing or preservation techniques. Existing preservation techniques:[20]

  1. Nothing i.e. bottled fresh sap (shelf life: 2–5 days refrigerated)
  2. Filtered with a 0,22μ net (shelf life: 3 weeks refrigerated)
  3. Collected under anaerobic conditions (shelf life: 1 year ambient)
  4. Added sugar (3g per 100ml)[1]
  5. 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.
  6. Frozen at -25C (shelflife: 2 years)

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[21] and Canada, and from several species in Latvia, Russia, Belarus and Ukraine.

References[edit]

  1. ^ a b c d Svanberg, Ingvar; et al. (2012). Uses of tree saps in northern and eastern parts of Europe. Acta Soc Bot Po. doi:10.5586/asbp.2012.036.
  2. ^ https://scholarworks.alaska.edu/bitstream/handle/11122/3198/Some%20impacts%20to%20paper%20birch%20trees%20tapped%20for%20sap%20harvesting%20in%20Alaska.pdf?sequence=1
  3. ^ https://scholarworks.alaska.edu/bitstream/handle/11122/3198/Some%20impacts%20to%20paper%20birch%20trees%20tapped%20for%20sap%20harvesting%20in%20Alaska.pdf?sequence=1
  4. ^ https://scholarworks.alaska.edu/bitstream/handle/11122/3198/Some%20impacts%20to%20paper%20birch%20trees%20tapped%20for%20sap%20harvesting%20in%20Alaska.pdf?sequence=1
  5. ^ https://scholarworks.alaska.edu/bitstream/handle/11122/3198/Some%20impacts%20to%20paper%20birch%20trees%20tapped%20for%20sap%20harvesting%20in%20Alaska.pdf?sequence=1
  6. ^ https://scholarworks.alaska.edu/bitstream/handle/11122/3198/Some%20impacts%20to%20paper%20birch%20trees%20tapped%20for%20sap%20harvesting%20in%20Alaska.pdf?sequence=1
  7. ^ Hopman, Ellen Evert (2008-06-09). A Druid's Herbal of Sacred Tree Medicine. Simon and Schuster. ISBN 9781594777240.
  8. ^ "Birch Juice – Russiapedia Of Russian origin". russiapedia.rt.com. Retrieved 2018-09-24.
  9. ^ Planter og tradisjon: Floraen i levende tale og tradisjon i Norge, Ove Arbo Høeg, Universitetsforlaget, 1974, ISBN 8200089304.
  10. ^ Övre Dalarnes bondekultur 3, Lars Levander, Lund, 1947.
  11. ^ http://www.grouprecipes.com/80154/pennsylvania-birch-beer.html
  12. ^ Kūka, Māra (2013). Determination of Bioactive Compounds and Mineral Substances in Latvian Birch and Maple Saps. Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences. doi:10.2478/prolas-2013-0069.
  13. ^ Sosa, A (1935). "Un glucoside nouveau de Betula Alba L. Le bétuloside et son aglycone, le bétuligénol". Paris Masson Ed.
  14. ^ 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.
  15. ^ http://www2.publicationsduquebec.gouv.qc.ca/essences/arbre.php?id=98
  16. ^ Bouchet, Jérome (2007). "Les Stratégies en Thérapeutique Antivirale": 24.
  17. ^ http://www.santenatureinnovation.com/la-seve-de-bouleau-est-deja-la/
  18. ^ a b Demirci, B; Demirci, F; Hüsnü Can Baser, K; Franz, G (2004). "Essential oil of Betula pendula Roth. Buds". Evid. Based Complement. 1 (3): 301–303. doi:10.1093/ecam/neh041. PMC 538512. PMID 15841263.
  19. ^ 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.
  20. ^ Nicole & Olivier Lhomme, NICOLL-Nature, Le Bio Logis, La sève de bouleau
  21. ^ 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.