13,591
edits
Changes
no edit summary
Upon learning about cyanogenic glycosides, brewers often question the toxicity of cherry pits or apricot kernels in beer. Cherry pits have traditionally been used in [[lambic]] kriek beers in Belgium. However, the dilution of HCN from cherry pits in beer results in benign levels. Assuming full breakdown of these glycosides, and that none of the HCN boils off (25.6°C boiling temperature), levels of HCN introduced from cherry pits are too low to cause harm to adult humans. The EU regulates that alcoholic beverages cannot exceed 1 mg of HCN per ABV percentage (v/v%) per liter <ref>[http://ec.europa.eu/food/fs/sfp/addit_flavor/flav09_en.pdf COUNCIL DIRECTIVE of 22 June 1988 on the approximation of the laws of the Member States relating to flavourings for use in foodstuffs and to source materials for their production (88/388/EEC). The European Food Commission, Food Safety. Retrieved 08/26/2016</ref>. Luk Daenen, a glycoside researcher, calculated that for a 4% ABV alcohol beer, 4 mg of HCN per liter is allowed. With 200 grams of cherries per liter, and the pits being 10-14 grams of that weight, there is 22 - 30.8 amygdalin per liter of beer. Around 6% of the weight of amygdalin is converted into HCN. Assuming maximum extraction of HCN from the amygdalin glycoside, which is unlikely because the pits are not ground up when used in beer, this equates to 1.3 - 1.82 mg of HCN per liter of beer, which is less than the 4 mg of HCN per liter that the EU regulation states. Considering that ~42 mg of HCN is required to kill a person that weighs 70 kilograms (154 pounds), that person would need to drink around 23 liters of beer <ref name="daenen">[https://www.uclouvain.be/cps/ucl/doc/inbr/documents/presentation-luk-daenen.pdf "Use of beta-glucosidase activity for flavour enhancement in specialty beers," slideshow by Luk Daenen. 2012. Retrieved 08/26/2016.]</ref>. 350 mL of alcohol would kill a 70 kilogram adult <ref>[http://www.alcohol.org.nz/alcohol-its-effects/health-effects/alcohol-poisoning "Alcohol Poisoning". NZ Health Promotion Agency. Retrieved 08/26/2016.]</ref>. The amount of 4% ABV beer required to kill a 70 kg adult from alcohol poisoning is around 8.75 liters. Alcohol would kill such a person far before cyanide poisoning would become a concern. In general, the potential cyanide in most foods will become too dilute to have any health problems, however there might still be plants that are extremely high in HCN content that they should be avoided in beer.
Some cyanogenic foods can have their cyanogenic glycosides reduced by cooking them at 230°C for 15 minutes (flaxseed, for example) <ref name="Chaouali"></ref><ref name="flax"></ref>, however some amygdalin based cyanogenic plants may have their amygdalin content reduced to about 25% by cooking alone (apricot seeds, for example). Fermentation by certain species of microbes can have a greater effect on reducing amygdalin to HCN than cooking alone. Microbes that have been shown to break down amygdalin include some species of lactic acid bacteria including ''Lactobacillus plantarum'', and fungi such as ''Endomyces fibuliger'', ''Pichia etchellsii'', and ''Hanseniaspora valbyensis''. Some strains of ''Brettanomyces'' that have high beta-glucosidase activity might be able to break down amygdalin by around 5064%, and some strains of ''S. cerevisiae'' might be able to break down up to around 10% of amygdalin, but this needs to be verified by science. Once hte amydalin is broken down into HCN, the HCN can then be volatilized off by cooking in a ventilated space <ref>[Simple screening procedure for microorganisms to degrade amygdalin. L. Brimer, G. Tunçel, M. J. R. Nout. 1993.]</ref><ref>[http://www.ncbi.nlm.nih.gov/pubmed/7710917 Microbial degradation of amygdalin of bitter apricot seeds (Prunus armeniaca). Nout MJ, Tunçel G, Brimer L. 1995.]</ref><ref name="Daenen1"></ref>. In normal brewing procedures, however, the beer is not cooked nor ventilated, so any HCN that is produced by the breakdown of cyanogenic glycosides should be presumed to remain in the beer.
{| class="wikitable sortable"