Changes

The spontaneous fermentation of lambic is a complex process involving a succession of bacteria and yeasts that progresses along with the chemical changes that occur during fermentation.<ref name=GeuzeKriek>Jef Van den Steen, [[Books#Geuze & Kriek: The Secret of Lambic Beer|Geuze & Kriek: The Secret of Lambic Beer]], 2012</ref> The spontaneous fermentation process has shown considerable variability even among different barrels of beer from the same brewery,<ref name=Spitaels > F. Spitaels, A. D. Wieme, M. Janssens, M. Aerts, H.-M. Daniel, A. Van Landschoot, L. De Vuyst, P. Vandamme [http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0095384 | The Microbial Diversity of Traditional Spontaneously Fermented Lambic Beer], 2000</ref> though all spontaneiously spontaneously fermented beers appear to follow a general sequence of microbes, which can be broken into four distinct stages:<ref name=AWAs>Nicholas A. Bokulich, Charles W. Bamforth, David A. Mills. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0035507|Brewhouse-Resident Microbiota Are Responsible for Multi-Stage Fermentation of American Coolship Ale], PLoS One, 7(4), 2012</ref><ref name=Oevelen77 >D. Van Oevelen, M. Spaepen, P. Timmermans and H. Verachtert, [http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1977.tb03825.x/abstract|MICROBIOLOGICAL ASPECTS OF SPONTANEOUS WORT FERMENTATION IN THE PRODUCTION OF LAMBIC AND GUEUZE], 1977</ref><ref name=Spitaels > F. Spitaels, A. D. Wieme, M. Janssens, M. Aerts, H.-M. Daniel, A. Van Landschoot, L. De Vuyst, P. Vandamme [http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0095384 | The Microbial Diversity of Traditional Spontaneously Fermented Lambic Beer], 2000</ref>

# [[Saccharomyces]] dominance, lasting from 3 to about 30 weeks, in which Saccharomyces cerveciae cerevisiae and other Saccharomyces species dominate the beer's yeast flora.

After the pH falls below ~4.5 and the alcohol content rises over ~2%, [[Saccharomyces| Saccharomyces species]] take over as the dominant organisms in the wort, though Saccharomyces is present in large numbers well prior to the dissapearance disappearance of the enterobacteria. Saccharomyces will remain dominant until at least 6 to 8 months into fermentation, and will maintain a presence, though no longer active, throughout fermentation. Despite Saccharomyces' importance to the fermentation of Lambiclambic, its concentrations remain below 10⁷ cells per mL of wort, which is considerably lower than the 10⁸ cells/mL found in commercial beers.<ref name=Oevelen77 >D. Van Oevelen, M. Spaepen, P. Timmermans and H. Verachtert, [http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1977.tb03825.x/abstract|MICROBIOLOGICAL ASPECTS OF SPONTANEOUS WORT FERMENTATION IN THE PRODUCTION OF LAMBIC AND GUEUZE], 1977</ref><ref name="Guinard">Jean-Xavier Guinard, [[Books#Classic Beer Styles: Lambic|Classic Beer Styles: Lambic]], 1990</ref>

As in controlled fermentation, Saccharomyces is responsible for most ethanol production and attenuation in lambic. The yeasts consume all the major sugars found in lambic wort (glucose, maltose, and some maltotriose). By the end of the Saccharomyces phase around 8 months, the ethanol content of the beer stabilizes at 5 to 7% by volume and will remain around that value until the end of fermentation.<ref name="Guinard">Jean-Xavier Guinard, [[Books#Classic Beer Styles: Lambic|Classic Beer Styles: Lambic]], 1990</ref><ref name=Oevelen77 >D. Van Oevelen, M. Spaepen, P. Timmermans and H. Verachtert, [http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1977.tb03825.x/abstract|MICROBIOLOGICAL ASPECTS OF SPONTANEOUS WORT FERMENTATION IN THE PRODUCTION OF LAMBIC AND GUEUZE], 1977</ref> Attenuation after Saccharomyces fermentation reaches 60 to 65%, which is known as the "attenuation limit" for conventional beers. Despite being responsible for most of the ethanol in Lambiclambic, yeasts of the Saccharomyces genus are not responsible for most of the aroma and flavor compounds that give Lambic lambic its distinct sensory characteristics.<ref name = Witrick1> K. A. T. Witrick [https://vtechworks.lib.vt.edu/handle/10919/19203| Characterization of aroma and flavor compounds present in lambic (gueuze) beer], 2012 </ref>

After the changing environment of the wort ends the growth of the enteric bacteria around 30 to 60 days, bacteria of the pediococcus come to dominate the bacterial flora. Lactobacillus can also be found in the wort in large numbers at this time, and both genuses are responsible for most of the [[Lactic acid|lactic acid]] in Lambiclambic. Collectively these bacteria are known as the lactic acid bacteria.

Interestingly, lactic acid bacteria have been implicated in racemizing amino acids in beer, causing Lambic lambic (and other beers which make use of lactic acid bacteria such as Berliner Wiesse) to have a high percentage of right-handed amino acid stereoisomers relative to both their starting materials and other beers.<ref name=Erbe >T. Erbe and H. Brückner, [http://www.sciencedirect.com/science/article/pii/S0021967300002557|Chromatographic determination of amino acid enantiomers in beers and raw materials used for their manufacture], 2000</ref>

Brettanomyces has been implicated in producing most of the aroma compounds in Lambic.<ref name="Guinard">Jean-Xavier Guinard, [[Books#Classic Beer Styles: Lambic|Classic Beer Styles: Lambic]], 1990</ref> Sensory-significant quantities of ethyl acetate and ethyl lactate form at this time from ethanol entering into an ester bond with [[Acetic acid|acetic]] and [[lactic acid]], respectively. The esterization process is greatly helped by the enzyme esterase provided by Brettanomyces. However, the enzymatic esterization is highly reversible and esters found in high concentrations in the lambic prior to the presence of the esterase will achieve a lower equilibrium. This is the case with iso-amyl acetate, which is produced by Saccharomyces and is a characteristic odor compound in many other beers. Tetrahydropyridines (THPs) produced by Brettanomyces (as well as some Lactobacilli) have a wide variety of odors and give Lambic lambic much of its "mousey" aroma, as well as cider- and horse-like aromas, though the concentrations and thus smells of THPs are variable.<ref name=Heresztyn1> T. Heresztyn [http://ajevonline.org/content/37/2/127.short| Formation of Substituted Tetrahydropyridines by Species of Brettanomyces and Lactobacillus Isolated from Mousy Wines], 1986</ref> Other important odor and flavor compounds produced by Brettanomyces include 4-ethylphenol, 4-ethylguaiacol, and isovaleric acid. 4-ethylphenol produces barnyard and horsey flavors which can taste like Band-aids in higher concentrations. 4-ethylguaiacol lends spicier flavors of bacon and cloves and can be smoky, while isovaleric acid gives Lambic lambic its sweaty and cheesy flavors and odors.

Gueuze and other lambic bottled with either some residual sugar left unfermented at the time of bottling or added priming sugars will undergo significant fermentation in the bottle, though all unpasteurized lambic will continue to ferment to some degree there. For lambic bottled after about 8 months without additional sugar, the fermentation in the bottle progresses much as an extension of the Brettanomyces stage of fermentation and negligible carbon dioxide and ethanol production occurrsoccurs, leaving most of this lambic still. For lambic bottled younger and those with additional fermentable sugars added at bottling, considerable fermentation by Saccharomyces occurs in the bottle, causing marked increases in ethanol and the production of carbon dioxide, leading to a carbonated product.<ref name=Oevelen77 >D. Van Oevelen, M. Spaepen, P. Timmermans and H. Verachtert, [http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1977.tb03825.x/abstract|MICROBIOLOGICAL ASPECTS OF SPONTANEOUS WORT FERMENTATION IN THE PRODUCTION OF LAMBIC AND GUEUZE], 1977</ref>

The reactivation of Saccharomyces fermentation at the addition of additional sugar indicates that the dominance of Brettanomyces is brought about by Brettanomyces' ability to ferment sugars that Saccharomyces cannot. Once Saccharomyces has consumed most of the available glucose and other simple sugars in the wort, it goes dormant, though does not die completely, and Brettanomyces is free to assume the role of primary yeast in the wort. Upon the re-introduction of the simple sugars, the faster-growing Saccharomyces once again flourishes, until the again the fermentable sugar is again consumed and Brettanomyces and its other associated yeasts can once again resume the slow procress process of the final fermentation.

The ongoing process of Lambic lambic aging after its maturation is a very complex process and has both purely chemical as well as biochemical aspects. Much of the present literature is general to all beer.

The decomposition of the yeast progresses primarily through the action of their own enzymes in a process called autolysis. Autolysis releases a large number of other enzymes, which has the secondary effect of breaking down many other components of the beer.<ref name=Vanderhaegen1> B. Vanderhaegen, H. Neven, H. Verachtert, G. Derdelinckx [http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCAQFjAA&url=http%3A%2F%2Fwww.researchgate.net%2Fprofile%2FGuy_Derdelinckx%2Fpublication%2F222839054_The_chemistry_of_beer_aging__a_critical_review%2Flinks%2F0c960523339c4b25a6000000.pdf&ei=Tq3IVKmfFcGyogSs_YLQCA&usg=AFQjCNFaBrvqDGjqEV2I9uQ73dYh_ParXg&sig2=Z8dY4iDHozbT1eb9JeAdrw&bvm=bv.84607526,d.cGU| The chemistry of beer aging – a critical review], 2006</ref> The release of esterase leads to the increased destruction of iso-amyl acetate and other esters, causing a loss of its light, fruity odor. Not all esters are broken down by this process, and a number of esters are formed during aging. These include ethyl 3-methyl-butyrate and ethyl 2-methyl-butyrate which contribute a light floral or even tropical fruit odor.<ref name=Bohmann2> J. J. Bohmann [http://www.brewingscience.de/index.php?tpl=table_of_contents&year=1985&edition=0004&article=56947| Zum Alterungsverhalten des Bieres. 4 Teil, Kombinierte Alterungsversuche durch Begasung mit Kohlendioxid, Stickstoff, Luft und Sauerstoff], 1985</ref><ref name=Bohmann1> J. J. Bohmann [http://www.brewingscience.de/index.php?tpl=table_of_contents&year=1985&edition=0003&article=56946| Zum Alterungsverhalten des Bieres. 3. Teil, Der Einfluß der Strahlungsbelastung, dargestellt am Beispiel 2-Methyl-2-buten und Isopren], 1985</ref> The release of proteases by autolysis causes a breakdown of long protein chains, with its concordant thinning of mouthfeel and reduction in head. While autolysis is often seen as undesirable, it can contribute to a pleasant mouthfeel as well as some of the characteristic flavors found in very old Lambiclambic.<ref name="Oxford pg 54">J. Robinson (ed) ''"The Oxford Companion to Wine"'' Third Edition pg 54 Oxford University Press 2006 ISBN 0-19-860990-6</ref>

While oxidation can occur rapidly due to a break in the fidelity of the seal at the cork, oxidation can still occur without the passage of oxygen through the cork or significant oxygen gas in the headspace due to the transfer of oxygen from an oxidizing coumpound compound in the wort to others. The act of losing an oxygen, or more generally, of losing electrons, is called reduction.

The Mailard Maillard reaction, also responsible for the browning of toast and steak among many other things, occurs in the unfermented reducing sugars left in the beer during extended aging, leading to a darker brown color as well as a slight burnt toast flavor.<ref name=Vanderhaegen1> B. Vanderhaegen, H. Neven, H. Verachtert, G. Derdelinckx [http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCAQFjAA&url=http%3A%2F%2Fwww.researchgate.net%2Fprofile%2FGuy_Derdelinckx%2Fpublication%2F222839054_The_chemistry_of_beer_aging__a_critical_review%2Flinks%2F0c960523339c4b25a6000000.pdf&ei=Tq3IVKmfFcGyogSs_YLQCA&usg=AFQjCNFaBrvqDGjqEV2I9uQ73dYh_ParXg&sig2=Z8dY4iDHozbT1eb9JeAdrw&bvm=bv.84607526,d.cGU| The chemistry of beer aging – a critical review], 2006</ref>

Many other reactions occur as Lambic lambic ages that are not elaborated upon here in the interests of brevity.

The microbes found in Lambic lambic may come from a variety of sources, as nearly every surface and even the air found in the brewery are teeming with life. While the air above the [[koelschip]] is often cited as the source of the microorganisms in Lambiclambic, other sources are now known to play a significant role.

Each reservoir potentially contributes different organisms to the Lambiclambic. Samples taken from a Lambic lambic brewery indicate that the air above the [[koelschip]] and in the cellar is the primary source of the bacteria in the Lambiclambic, while the barrels host much of the yeast, though some yeasts are found in the air and some bacteria come from the barrels as well. <ref name=Spitaels > F. Spitaels, A. D. Wieme, M. Janssens, M. Aerts, H.-M. Daniel, A. Van Landschoot, L. De Vuyst, P. Vandamme [http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0095384| The Microbial Diversity of Traditional Spontaneously Fermented Lambic Beer], 2000</ref>

The rapid reproduction of the microorganisms found in Lambic lambic also lends to them the ability to evolve on much shorter timescales than those of macroorganisms. Combined with the flora found in Lambic lambic (and other spontaneous fermentations) being largely resident inside each brewery,<ref name=AWAs> Nicholas A. Bokulich, Charles W. Bamforth, David A. Mills. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0035507 | Brewhouse-Resident Microbiota Are Responsible for Multi-Stage Fermentation of American Coolship Ale], PLoS One, 7(4), 2012</ref><ref name=Oevelen77 >D. Van Oevelen, M. Spaepen, P. Timmermans and H. Verachtert, [http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1977.tb03825.x/abstract|MICROBIOLOGICAL ASPECTS OF SPONTANEOUS WORT FERMENTATION IN THE PRODUCTION OF LAMBIC AND GUEUZE], 1977</ref> it is reasonable to assume that even the slight geographic separation found between the facilities within the Pajottenland will lead to markedly different strains of the bacteria and yeasts after several years of operation. Thus, it is reasonable to assume that at least part of the distinct flavors found in the Lambics lambics of each brewery are due to divergent evolution in their respective microbiomes,<ref name = Witrick1> K. A. T. Witrick [https://vtechworks.lib.vt.edu/handle/10919/19203| Characterization of aroma and flavor compounds present in lambic (gueuze) beer], 2012 </ref> though little literature currently exists in this area. For other breweries, "house strains" developed by propagating favorite yeasts often over a period of years and even decades is commonplace, and often accounts for much of a brewery's specific taste.

Conversely, it has been found that spontaneous fermentations in similar worts in other parts of the world follow similar overall trends.<ref name=AWAs> Nicholas A. Bokulich, Charles W. Bamforth, David A. Mills. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0035507 | Brewhouse-Resident Microbiota Are Responsible for Multi-Stage Fermentation of American Coolship Ale], PLoS One, 7(4), 2012</ref> Yeasts such as Saccharomyces and Brettanomyces and bacteria such as the enterobacteria and Pediococcus are cosmopolitan throughout the world, and all are similar enough to be classified into the same genus by both phenotype and genotype. However, the large degree of geographic separation coupled with the rapid evolutionary rates of these organisms will still lead to measurable changes in both. This is highlighted in the fact that while many Lambiclambic-like beers have been brewed in other parts of the world, and are often very similar to Lambic lambic itself, they still posess noticably possess noticeably different sensory characteristics. This can be likened to terrior terroir in wine, as the local microbiome in one location will produce a similar, but not identical, product to that in another location.

As an example, Brettanomyces shows significant genomic variation between strains, as well as a corresponding variability in their metabolisms, indicating that different strains of Brettanomyces bruxellensis will lend markedly different sensory characteristics to Lambiclambic.<ref name = Conterno1> L. Conterno, C. M. L. Joseph, T. J. Arvik, T. Henick-Kling, and L. F. Bisson [http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CC0QFjAB&url=http%3A%2F%2Fwww.researchgate.net%2Fprofile%2FC_M_Joseph%2Fpublication%2F236843438_Genetic_and_Physiological_Characterization_of_Brettanomyces_bruxellensis_Strains_Isolated_from_Wines%2Flinks%2F0c960528eb2e4a0513000000.pdf&ei=t6HKVJbHJZWyoQT2qoCYBg&usg=AFQjCNFMfoISmHrGfWtGfDHJWJI4w25vOw&sig2=u9Loxwy3zVWXK4gy8vn_2g&bvm=bv.84607526,d.cGU| Genetic and Physiological Characterization of Brettanomyces bruxellensis Strains Isolated from Wines], 2006</ref><ref name=Borneman1> A. R. Borneman, R. Zeppel, P. J. Chambers, C. D. Curtin [http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1004161| Insights into the Dekkera bruxellensis Genomic Landscape: Comparative Genomics Reveals Variations in Ploidy and Nutrient Utilisation Potential amongst Wine Isolates], 2014</ref><ref name = Yakobson> [http://www.brettanomycesproject.com/dissertation/ Brettanomyces Project Dissertation], Chad Michael Yakobson</ref><ref name = Curtin> C. D. Curtin, J. R. Bellon, P. A. Henschke, P. W. Godden, and M. A. de Barros Lopes [http://www.pubfacts.com/detail/17233769/Genetic-diversity-of-Dekkera-bruxellensis-yeasts-isolated-from-Australian-wineries.| Genetic diversity of Dekkera bruxellensis yeasts isolated from Australian wineries], 2007</ref><ref name = Agnolucci> M. Agnolucci, I. Vigentini, G. Capurso, A. Merico, A. Tirelli, C. Compagno, R. Foschino, M. Nuti [http://www.researchgate.net/publication/222660112_Genetic_diversity_and_physiological_traits_of_Brettanomyces_bruxellensis_strains_isolated_from_Tuscan_Sangiovese_wines| Genetic diversity and physiological traits of Brettanomyces bruxellensis strains isolated from Tuscan Sangiovese wines], 2009</ref>

Little research exists correlating the season of brewing to changes in the microbiology and chemistry of Lambiclambic; however, a delay in the appearance of the late-fermentation bacterial flora in Lambic lambic was observed when fermentation started earlier in the brewing season, leading to cooler fermentation temperatures.<ref name=Spitaels > F. Spitaels, A. D. Wieme, M. Janssens, M. Aerts, H.-M. Daniel, A. Van Landschoot, L. De Vuyst, P. Vandamme [http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0095384| The Microbial Diversity of Traditional Spontaneously Fermented Lambic Beer], 2000</ref> The flora were indistinguishible after 18 months.

Similarly, a study on spontaneously fermented ales in the United States revealed marked differences between ales brewed in the spring versus those in the winter.<ref name=AWAs>Nicholas A. Bokulich, Charles W. Bamforth, David A. Mills. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0035507| Brewhouse-Resident Microbiota Are Responsible for Multi-Stage Fermentation of American Coolship Ale], PLoS One, 7(4), 2012</ref> The flora broadly follow the same pattern of succession regardless of the season of innoculation, although genetic analysis showed distinct differences between the flora responsible for fermentation arriving in the spring and winter. The differences between the organisms found in the wort innoculated at different seasons were smaller than the differences arising from the elapsed time after brewing at sampling. By 36 weeks, there was no longer a noticable noticeable difference in the flora of ale brewed in the winter versus in the spring.

Spontaneous fermentation is important to a wide variety of foodstuffs other than Lambiclambic, ranging from very similar modern beers brewed in other parts of the world to cheeses and pickled vegetables.

Spontaneously fermented beers from the United States (and occasionally other parts of the world) form a group of beers referred to as American Coolship Ales (or ACAs), American Wild Ales (or AWAs), among other names.<ref name=AWAs>Nicholas A. Bokulich, Charles W. Bamforth, David A. Mills. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0035507|Brewhouse-Resident Microbiota Are Responsible for Multi-Stage Fermentation of American Coolship Ale], PLoS One, 7(4), 2012</ref> ACAs vary in their intended similarity to Lambiclambic, with some American producers even going so far as to label their beers "Lambicslambics", while other ACAs bear little in common with Lambic lambic besides spontaneous fermentation. Due to the geographical separation between the United States and Belgium and the large variations in yeast and bacteria genetics between these different populations, even an ACA wort carefully prepared to be very similar to that of Lambic lambic will yield notably different results after fermentation, even if the overall experience of the two styles of beer is similar.<ref name=AWAs>Nicholas A. Bokulich, Charles W. Bamforth, David A. Mills. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0035507|Brewhouse-Resident Microbiota Are Responsible for Multi-Stage Fermentation of American Coolship Ale], PLoS One, 7(4), 2012</ref> <ref name=sour> J. Edwards and A. DiCaprio. [http://www.process-nmr.com/pdfs/Edwards%20-%20SMASH%202014%20-%20MNova%20Users%20Meeting%20-%209-7-14.pdf| When Beer Goes Sour: An NMR Investigation], Mestrelab

Other spontaneous fermentations exist as well, such as Chicha, a corn-based lightly alcoholic drink indigenous to the Andes. Much like the spontaneous fermentation of Lambiclambic, Chicha posesses possesses its own set of yeasts, dominated by strains of Saccharomyces responsible for its unique characteristics.<ref name=Vallejoa >J. A. Vallejoa, P. Mirandaa, J. D. Flores-Félixb, F. Sánchez-Juanesc, J. M. Ageitosa, J. M. González-Buitragoc, E. Velázquezb, T. G. Villaa, [http://www.sciencedirect.com/science/article/pii/S0723202013001513| Atypical yeasts identified as Saccharomyces cerevisiae by MALDI-TOF MS and gene sequencing are the main responsible of fermentation of chicha, a traditional beverage from Peru], 2013</ref>

Brettanomyces and other wild organisms, despite often being spoilage organisms in wine, are responsible for some major sensory characteristics of some wine styles.<ref name=Tristezza> M. Tristezza, C. Vetrano, G. Bleve, G. Spano, V. Capozzi, A. Logrieco, G. Mita, F. Grieco [http://www.sciencedirect.com/science/article/pii/S0740002013001408 | Biodiversity and safety aspects of yeast strains characterized from vineyards and spontaneous fermentations in the Apulia Region, Italy], 2013</ref><ref name=Medina> K. Medina, E. Boido, L. Fariña, O. Gioia, M.E. Gomez, M. Barquet, C. Gaggero, E. Dellacassa, F. Carrau [http://www.sciencedirect.com/science/article/pii/S0308814613005025 | Increased flavour diversity of Chardonnay wines by spontaneous fermentation and co-fermentation with Hanseniaspora vineae], 2013</ref> Other minor yeasts found in Lambiclambic, such as Pichia and Kloeckera, have also been found in unspoiled wine.<ref name=Tristezza> M. Tristezza, C. Vetrano, G. Bleve, G. Spano, V. Capozzi, A. Logrieco, G. Mita, F. Grieco [http://www.sciencedirect.com/science/article/pii/S0740002013001408 | Biodiversity and safety aspects of yeast strains characterized from vineyards and spontaneous fermentations in the Apulia Region, Italy], 2013</ref><ref name=Medina> K. Medina, E. Boido, L. Fariña, O. Gioia, M.E. Gomez, M. Barquet, C. Gaggero, E. Dellacassa, F. Carrau [http://www.sciencedirect.com/science/article/pii/S0308814613005025 | Increased flavour diversity of Chardonnay wines by spontaneous fermentation and co-fermentation with Hanseniaspora vineae], 2013</ref>

Spontaneous fermentation is a complex process compared to the cultured fermentations of other beers. Several genera of both yeast and bacteria are involved in making the final product. The order in which these organisms dominate the flora allows us to divide the fermentation process into several distinct stages. We have chosen to divide the process into four distinct parts. First, colonization by enteric bacteria, which is responsible for production of acetic acid in the wort, followed by the growth of the yeasts Kloeckera and then Saccharomyces, which ferment most of the simple sugars and produce the majority of the ethanol in Lambiclambic. During the Saccharomyces dominanace of the yeast flora, the bacterial flora switch to primarily lactic acid bacteria, which do exactly what you'd expect something with that name to do. At the end of fermentation, Brettanomyces comes to dominate the yeast flora, and the slow fermentation by these organisms is responsible for many of the odors and flavors associated with Lambiclambic. The aging process then continues well after the beer is bottled. Geographic and seasonal variation, coupled with the "wild" nature of spontaneous fermentation in general, conspires to make Lambic lambic a truly unique product.