Extraction of birch sap

Birch sap, birch water or birch juice is the sap directly tapped from birch trees, Betula pubescens (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

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.

Slavic regions

In Slavic regions the sap is known as birch juice as in Russia (Russian: берёзовый сок, romanized: byeryozovyi sok), Belarus (Belarusian: бярозавы сок, romanized: biarozavy sok, Byarozavik), Bulgaria (Bulgarian: брезов сок, romanized: brezov sok), Poland (Polish: sok z brzozy, oskoła), Slovakia (Slovak: brezová šťava), Ukraine (Ukrainian: березовий сік, romanized: berezovyi sik).

Baltic regions

Estonia (Estonian: kasemahl), Finland (Finnish: mahla), Latvia (Latvian: bērzu sula), Lithuania (Lithuanian: beržo sula, beržų sula).

Other regions

France, Scotland, Norway,[5] Sweden (Swedish: björksav)[6] and elsewhere in Northern Europe[1] 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, both as a traditional beverage in its own right, and particularly as a key ingredient in birch beer.[7]

Composition

Sap, birch water[8]
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),[9] 17 amino acids including glutamic acid,[10] as well as minerals, enzymes, proteins, betulinic acid and betulin,[11][12][13] antioxidants,[14] sugar (fructose, glucose and small amounts of sucrose) and vitamins (C and B(group)).[14] 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).[15]

Nutritional and medicinal uses

Folk uses

Folk uses have been documented which include medicinal use, supplementary nutrition, and cosmetic applications for skin and hair.[1]

RegionTraditional medicinal useCosmetic use
Belaruslung diseases, gout, sicknesswashing hair
Bulgariahair growth
Czech Republicpoor health, infertilityagainst freckles
Estonia(prevention of) eye diseases, skin diseases, source of 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

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:[16]

  • 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)
  • Added sugar (3 g per 100 ml)[1]
  • 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 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[17] and Canada, and from several species in Latvia, Russia, Belarus, and Ukraine.

References

  1. 1 2 3 4 Svanberg, Ingvar; et al. (2012). "Uses of tree saps in northern and eastern parts of Europe". Acta Soc Bot Pol. 81 (4): 343–357. doi:10.5586/asbp.2012.036. hdl:10278/3694733.
  2. 1 2 3 4 5 Trummer, Lori; Malone, Tom (May 2009). "Some impacts to paper birch trees tapped for sap harvesting in Alaska" (PDF). Us Forest Service. R10-S&PF-FHP-2009-3.
  3. ↑ Chepaitis, Barbara (14 April 2016). "Tapping Trees, Drinking Lighting: Baltic Birch Juice". Deep Baltic. Retrieved 24 September 2018.
  4. ↑ Hopman, Ellen Evert (2008-06-09). A Druid's Herbal of Sacred Tree Medicine. Simon and Schuster. ISBN 9781594777240.
  5. ↑ Planter og tradisjon: Floraen i levende tale og tradisjon i Norge, Ove Arbo Høeg, Universitetsforlaget, 1974, ISBN 8200089304.
  6. ↑ Övre Dalarnes bondekultur 3, Lars Levander, Lund, 1947.
  7. ↑ "Pennsylvania Birch Beer Recipe". www.grouprecipes.com.
  8. ↑ 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. 67 (4–5): 437–441. doi:10.2478/prolas-2013-0069. S2CID 49739804.
  9. ↑ Sosa, A (1935). "Un glucoside nouveau de Betula Alba L. Le bétuloside et son aglycone, le bétuligénol". Paris Masson ed.
  10. ↑ 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.
  11. ↑ "Bouleau à papier (BOP)". www2.publicationsduquebec.gouv.qc.ca.
  12. ↑ Bouchet, Jérome (2007). Les Stratégies en Thérapeutique Antivirale. p. 24.
  13. ↑ "Cure de sève de bouleau et ses bienfaits multiples". 10 March 2014.
  14. 1 2 Demirci, B; Demirci, F; Hüsnü Can Baser, K; Franz, G (2004). "Essential oil of Betula pendula Roth. Buds". Evidence-Based Complementary and Alternative Medicine. 1 (3): 301–303. doi:10.1093/ecam/neh041. PMC 538512. PMID 15841263.
  15. ↑ 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.
  16. ↑ Nicole & Olivier Lhomme, NICOLL-Nature, Le Bio Logis, La sève de bouleau
  17. ↑ 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.
Wikimedia Commons has media related to:
Birch sap
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.