Around 800 species of yeast have been described by science (Boekout and Samson), this is thought to be a tiny fraction of the total number of living species. In FF, yeasts are used primarily in alcoholic F. These include beer, wine, mead, sake, mirin as well as distilled alcoholic beverages such as vodka or schnapps. Leavened bread is also made using yeast. Yeast feed on sugars, principally glucose, when feeding in the presence of oxygen (aerobic conditions) producing energy (which they use) and carbon dioxide and water (which are discarded).
Glucose + O2 (arrow) CO2 + H2O + Energy
When without oxygen (anaerobic conditions) they can still (although less efficiently), produce chemical energy (ATP) but this time they produce CO2 and alcohol as products. In alcoholic fermentation of beverages, the liquids are denied oxygen using airlock systems to ensure alcoholic fermentation. In bread, the yeasts first use up available oxygen then begins its anaerobic respiration where it produces CO2 and ethanol, the CO2 accounts for the bubbles in the bread and the ethanol evaporates during cooking.
Glucose (arrow) CO2 + Ethanol + Energy
A certain amount of this happens in nature without intervention. Most of the skins from sugary fruits, grapes, apples, plums etc, are covered in a thin layer of wild yeasts (and other microorganisms). This means that as the fruit ripens, these yeasts will be using the available sugar. If we want to make a naturally fermented alcohol we can just leave the juices of sugar rich fruits in contact with their skins for a little while, and this small amount of contact should be enough to initiate alcoholic fermentation. The only thing to ensure if you want to use this natural fermentation method, that once the must starts to bubble, i.e. the yeasts take hold and begin transforming the sugars, that you attach an airlock system, so that the CO2 can escape without allowing oxygen to enter the container.
Airlocking systems which can easily be used are: (A) a classic shop bought airlock, not good for very vigourous fermentation (B) a tube leaving the top of the bottle enters into a container of water, good for vigorous fermentation (C) A balloon attached to the top of the bottle, bad for vigousous fermentation, but useful for slow fermentations, especially as the quantity of gas produced can be seen visually in the size of the balloon.
To look at this from a global perspective it is fascinating to remember that animals not only drink and enjoy alcohol, but some may even have something of a ‘culture’ of making it.
“There are many monkeys in Haung Shan. In the spring and summer they collect miscellaneous flowers and fruits and store them in a rocky crevice. In time they would ferment into a wine. The fragrant aroma would be detectable hundreds of steps away. A woodcutter venturing deep into the woods may come upon it. But he should not drink too much lest the monkeys discover the reduction of the amount of fluid left. If so, they would lie in wait for the thief and playfully torture him to death” (Huang, 2000, 245)
It is evident from fossils that fruit has played a major role in primate diet for at least the last 45 million years (Dudley and Stephens, 2004). As ripe fruits commonly contain yeasts it is expected that alcohol concentrations can be high enough to make plumes of alcohol in the air, which, when detected by aroma, can lead a primate to the fruit food source. It is argued that this is a possible basis for a genetic predisposition by humans toward alcohol as a hunger stimulant and indicator of nutritional value (Dudley, 2004). Indeed around 1/3 of the enzymes found in the human liver are involved in creating energy from alcohol (McGovern, 2010). Indeed it has been shown, especially in societies with lower hygiene, that drinking alcohol provides many functions, including the killing of pathogenic microorganisms in the gut. In all alcohol consuming societies, alcohol has been known to increase relaxation and social cohesion as well as uninhibiting libido, thus causing proliferation of alcohol consuming communities.
It is a popular opinion (although certainly not a definitive one) of archaeology and other humanities that populations gave up their nomadic lifestyles to take advantage of newly emerging innovative food production systems that evolved during the Neolithic revolution. Intentional and encouraged FF may have been one of them. Taking the earlier accounts of brewing monkeys and alcohol searching frugiverous primates as a starting point, it is easy to imagine humans developing alcoholic fermentation very early on in their cultural evolution.
Fermented foods are faster to cook, saving both time and fuel, have more accessible nutrients, provide interesting tastes to otherwise monotonous grain staples and can be more microbiologically safe. In the 1950’s a debate flared amongst archaeologists over which came first in human society, bread or beer. It was even argued that man might have lived on beer alone (Braidwood, 1953). The truth of the matter is much more likely to be that the two evolved together with prototypes being much more a slurry than the clarified beer or well-kneaded bread that we know so well today. It should be noted that a primitive beer could be much more nutritious than early man’s bread (McGovern, 2010).
It is thought that wild barley (Hordeum spontaneum) and other grains were first domesticated around 10,000 BP on the ‘Hilly Flanks’ between the Tigris and Euphrates rivers.. This was the birth of western agriculture and also a time when a series of new food preparation techniques such as soaking, heating and spicing first appeared. During times of plenty, grains from wild or cultivated grasses, or juices from fruits that had been collected would have, in a matter of a couple of days, started to ferment on their own. This process, which would have been unpredictable at best, was slowly developed as early peoples began to work out the complex relationships between the ingredients of a mixture and the time and conditions in which it was left.
The Neolithic revolution was possibly the single most important period in the history of humanity; Neolithic peoples in the Fertile Crescent (11,000 BP); the Yangtze and Yello River Basins (9000 BP); the New Guinea Highlands (9000-6000 BP); Sub-Saharan Africa (5000-4000 BP) and Eastern USA (4000-3000 BP) and possibly other places (Diamond and Bellwood, 2003) are credited with the invention of agriculture and of many foods, which continue to be consumed as staple foods to the present day, such as bread and beer. To start with, wet, and especially germinated grain would have started to ferment on its own, boiled grains and the juice of overripe fruits starting to bubble away – it would not have taken long for people to realize that those which turned alcoholic could give them an exciting and desirable psychological journey as well as social and medical benefits. Successful fermentation techniques spread between neighboring communities, and were developed in terms of available resources.
In the Nordic tradition perhaps the most interesting of ancient alcoholic beverages were derived from mixes of ingredients – an archaeological approach allows us the analysis of a Bronze Age burial in Egtved, Denmark. In this grave, which dates approximately from 1400 BC, was found a coffin containing a 20-year-old girl clutching a burnt child and, interesting for our purposes, a birch-bark (Betula sp.) container. Upon close inspection analyst Bille Gram ascertained the vessel originally contained cowberries (Vaccinium vitus-idaea), wheat grains, filaments of bog myrtle (Myrica gale) and pollen from lime tree (Tilia sp), meadowsweet (Filipendula ulmaria) and white clover (Trifolium repens), indicating the presence of honey. All of these ingredients have a history of being used in alcoholic beverages: the conclusion that can be drawn is that this pot once contained a mixed alcoholic beverage, of cowberry fruit wine, wheat beer and honey mead. This practice of mixing many fermentable ingredients is typical of prototypical beverages that archaeologists have unearthed from ancient burials from around the world (McGovern, 2010). They have frequently found remnants of alcoholic beverages, which more often than not, have been made form a mixture of different ingredients. (McGovern, 2010, 144).
Mead is perhaps known as the Nordic brew of choice. Famously in the English poem Beowulf, the Danish warriors drank mead in great quantities. The drink appears numerous times in Nordic mythology (Sturluson, 1220). Mead has been developed over the years with countless variants available and text being readily available for the interested reader (for example Schramm, 2003).
One curiosity of the area is the Ancient Sami culture of fermenting sap from the birch tree (Betula L.) to make a weak alcoholic beverage (approx 0.5-1% vol). The sap of the tree gives a marvelous bittersweet and floral flavour (similar but different to maple syrup) and is used in the brewing of Noma’s house beer.
Beer is well established in Nordic culture, Copenhagen being the birthplace of Carlsberg and other major breweries. A number of small, Danish artisan breweries, such as Fanoe Bryghus and Mikkeller are gaining market strength. Far from the purist influence of the German ‘Reinheitsgebot’ all sorts of extra spices and aromatics are being used, not only to increase the wealth and diversity of rich and aromatic finished beverages, but also to give expression of tradition and territory to the products (Fanoe brewery visit, 19/10/2011). In reality it can easily be argued that this is in fact a return to the origins of beer, originally a highly diverse culture of home brewing where many plants were added to the homemade brews, in the Nordic Countries; for example bog myrtle (Myrica gale) and labrador tea (Rhododendron groenlandicum) (Behre, 1999). 
As many people have dedicated their lives to experimenting with alcohol, most of our experiments have used alcohols, tinctures and distillates prepared by others. Which have come in diverse flavours such as tinctures made with the lichen, Iceland moss (Cetraria islandica). A typical Danish bitters, Gammel Dansk now appears on the Noma desert menu, it contains a mixture of 29 herbs and spices, and is comparable to the Italian Fernet Branca or German Jagermiester.
Behre, K.E. (1999) The history of beer additives in Europe – a review, Vegetation History and Archaeobotany 8: 35.
Boekout, T. and Samson, R. (2005) Fungal diversity and food, in Nout, M.J.R., De Vos, W.M., Zwietering, M.H. (eds) Food Fermentation pp. 29-44, Wageningen Academic Publishers, The Netherlands.
Braidwood, R.J. (1953) Symposium: did man once live by beer alone?, AmericanAnthropologist New Series 55 : 515.
Diamond, J. and Bellwood, P. (2003) Farmers and their languages: the first expansions, Science 300 : 597.
Dudley, R. (2004) Ethanol, fruit ripening, and the historical origins of human alcoholism in primate frugivory, Integrative & Comparative Biology 44: 315.
Dudley, R. and Stephens, D. (2004) The drunken monkey hypothesis, NaturalHistory 113 : 40.
Huang, H.T. (2000) Biology and biotechnology, in Needham, J. (ed) Science and Civilisation in China: Volume 6, Biology and Biological Technology, Part 5, Fermentations and Food Science, p. 245, Cambridge University Press, Cambridge, UK.
Sturlson, S. (1220) Edda ,Translated by Faulkes, A (1995) Everyman, London
Watson, P.J. (2005) Robert John Braidwood, Proceedings of The AmericanPhilosophical Society 149: 233.
About the author
My Name is Ben Reade, I’m a chef from Edinburgh, Scotland, and for the past 3.5 years I have been studying at The University of Gastronomic Sciences in Pollenzo, Italy. For my final thesis, I came to Nordic Food Lab to research many subjects where my varied interests inerlaced with those of the Lab. The research arose out of time spent at the Nordic Food Lab between 29 September and 22 December 2011. The aim is to describe NFL’s current research to both chefs and non-specialized readers, explaining and coding the creative and scientific methodologies employed during the research at NFL, exploring their application in food experimentation and innovation. Over the next month or so I will be breaking down this thesis into manageable blog-style chunks, this is chunk 6ish of around 25 I hope you find it interesting. If you want to ask me any questions directly, I’m contactable on Twitter @benreade.
 The Hilly Flanks were first described by Robert Braidwood in 1948 as the area in the fertile crescent where agriculture was born. (Watson, 2005)
 Sami are an indigenous reindeer herding population of Northern Scandinavia
 For more information on practical aspects of beer brewing, readers are referred to Palmer (2006).