Be filled with the spirit

[The Leaven – exploring the relationship between science and religion (cont)]

The words for wine used in the New Testament are oinos, a Greek term for completely fermented wine, and gleukos, used to denote new or sweet wine with less alcohol content. Gleukos as a reference to wine that has been drunk is only mentioned one time in the New Testament [Acts 2.13]. In the context of this passage the apostles were behaving in an unusual way because they were full of the Holy Spirit. Onlooker’s accused them of behaving as if they were drunk on gleukos because of how their behaviour had changed with no alcohol being present.

Biblical society viewed wine in a similar way to how it is currently perceived. They were aware that over indulgence could be harmful  but generally it was socially accepted. The New Testament attempts to rescue individuals from a drunken abyss by suggesting that they should be filled with a different kind of spirit:

Do not get drunk with wine, which will only ruin you; instead, be filled with the Spirit.
[Eph. 5.18]

In a comparatively brutal manner the Old Testament illustrates and blatantly condemns the consequences of intoxication:

The Lord God said to me, “Jeremiah, tell the people of Israel that every wine-jar should be filled with wine. They will answer that they know every wine-jar should be filled with wine. Then tell them that I, the Lord, am going to fill the people in the land with wine until they are drunk: the kings, who are David’s descendants, the priests, the prophets, and all the people of Jerusalem. Then I will smash them like jars against one another, old and young alike. No pity, compassion, or mercy will stop me from killing them.”
[Jer. 13.12-15]

The Roman’s took wine very seriously, to the extent that they even had a deity assigned to it, Bacchus. Even so some social groups were discouraged from drinking alcohol. For instance, women, in the early day of the Republic, were forbidden from drinking ordinary wine but were permitted to drink those with low alcohol content. There were a number of ways that the alcoholic content of wine could be reduced. Fermentation could be inhibited by increasing sugar content. The Romans called this beverage defrutum. Grape juice with enough sweetness to remain unfermented can be made by pressing dried grapes. Pliny refers to a raisin-wine, made from grapes dried to half their weight. Roman women also drank a wine alternative made of raisins called passum. Another method to reduce wine alcoholic content was to prevent the yeast from growing. Vinous fermentation occurs only within a certain temperature range, the lower limit is about 15°C. If cooled wine were allowed to sit undisturbed, the clear juice could be removed from the sediment and would remain unfermented. Another method of making a nonalcoholic wine was by adding salt, a process favoured by the Greeks and described by several classical authors (Cato, Columella and Pliny), this method was also used to preserve the must. Alcohol evaporates at below 100°C, so could be physically removed from the wine by heating. Pliny describes another drink called adynamon, made by adding water to wine and boiling the mixture until the quantity was considerably reduced. This provided a fortifying drink for invalids.

Bacchus, Roman God of Wine. Caravaggio, 1596

It is believed that the Hebrews were also familiar with preserving wine by boiling down grape juice to a thick syrup like molasses. The boiling process would also remove any microbial contaminants from the grapes. The syrup would be diluted with water as a drink or added to wine must.  Some of the Biblical references to honey debash could be referring to a sweet grape syrup. The Hebrew debash is similar to Arabic dibs, a sweet syrup made by boiling down the juice of grapes, raisins or dates.

In moderate use the social impact of yeast is beneficial but alcoholism is becoming a modern scourge of the 21st century replacing the problems caused by microbial diseases. In a recent study conducted by the World Health Organisation, the long-term health burden of alcohol related disease surpasses smoking and malnutrition. The countries that produce the highest quota of alcohol last century were the USA (beer), China (spirits) and France (wine). The leading exporter of alcohol was Great Britain, which exports nearly twice as much as France in second place. The total consumption of alcohol increased in Great Britain between the 1970’s and 1990’s while in France it decreased. However, in the 1990’s the French were still more likely to consume more alcohol per capita than the British, 14% compared to 9%.  In general, the Bible portrays the message that drinking wine is an acceptable part of every day life  but its increased accessibility by modern preservation and production methods seem to have created new social challenges.

The Blood of Christ

[The Leaven – exploring the relationship between science and religion (cont)]

In the molecular era, it is now known that fermentation is not only responsible for the leavening of bread but it is also the principle process in brewing and wine making. It ‘s worthwhile taking time to consider how wine was perceived in the biblical era and how its use is viewed in current religious ceremony. Present society now understands that the intoxicating agent of wine is alcohol, a by-product of the yeast fermentation process. It is also understood that unfermented fresh grape juice, or must, is relatively free from alcohol. These principles were not understood by ancient societies, as the knowledge behind the biology of fermentation did not exist. When leaven is used in making bread it is viewed as an impurity and therefore omitted from many sacrificial ceremonies. In contrast wine, which is also produced by a similar fermentation process involving yeast, was not only permitted in sacrifices but was sometimes a principal component.

Monk drinking wine. Grod c1800.

Wine production occurs naturally in the environment. Grape skins are covered with yeasts and bacteria, mainly members of  the yeast family Saccharomyces. When grapes are crushed they ferment, especially in warm climates as yeast fermentation occurs between 20 and 40°C with an optimum growth temperature of around 30°C. The main fermentation is aerobic and takes a few days. It then  continues anaerobically at a slower rate for some time. When fermentation is complete the resulting wine is racked from the sediment, a substance containing precipitated organic matter and yeast. In the biblical era wine is produced in animal skins or in jars designed specifically for the fermentation process. In the New Testament the fermentative characteristics of wine were well recognised as is evident in some of the passages. The following parable uses the properties of fermentation to describe how a flexible way of thinking was needed to accept new and fresh ideas:

Nor does anyone pour new wine into used wineskins, for the skins will burst, the wine will pour out, and the skins will be ruined. Instead, new wine is poured into fresh wineskins, and both will keep in good condition
[Matt. 9.17; Mk. 2.22; Lk. 5.37]

Wine is not referred to in the Bible as leaven or unleavened although it does feature in sacrifices and rituals. In the Old Testament it is used in large quantities as part of a daily sacrificial offering that also included animals and unleavened bread [Ex.29.38-46; Num. 28.1-8]. Wine is also offered on the Sabbath and on the first day of the month, where the quantity varies depending on the type of animal used in the sacrifice . Most notably, wine was offered in the daily sacrifice during the festival of the unleavened bread:

The proper wine-offering is two measures of wine with each bull, one and a half measures with the ram, and one measure with each lamb.
[Num. 28.9-15]

It does seem, in respect to sacrifices, that leaven was not associated with wine in the same way as it is associated with bread. Perhaps this is because the process of wine production was not as accessible to the overall population as bread making, therefore it is less likely to be used in domestic ceremonies due to lack of availability. Also as wine is intoxicating and bread is not,  perhaps fermentation in bread was simply thought of as a different process. In addition wine is rarely associated with food poisoning although it is possible for some microbial toxins to be found in wine. Generally if wine becomes contaminated during fermentation it is undrinkable and becomes cloudy, perhaps at this stage it might have been viewed as impure and corrupt. Pathogenic microbes usually require an optimal pH similar to that found in animals, this is why ethanol with a high pH is normally used in sterilisation. In fact this could be the reason why alcohol, similarly to salt, is used in these sacrifices, for its ability to sterilise and remove contamination.

… the man who turned vinegar in to wine: Louis Pasteur

[The Leaven – exploring the relationship between science and religion (cont)]

Mendel and Darwin worked in a parallel universe. They were both theologians whose discoveries emerged at the same time and resulted from a similar method of meticulous observations. Mendel’s work did not cause an upheaval equivalent to that of Darwin’s, as it described the laws of nature and did not directly threaten orthodox beliefs. Attention was focused mainly on the findings of Darwin and Wallace and, as a consequence the significance of Mendel’s results remained unappreciated until the beginning of the 20th century. The integration of Mendel’s findings with those of Darwin’s led to a greater understanding of inheritance and evolution but digressed from the common belief that Earth evolved only a few thousand years ago and that each species was created within a similar time-scale. Simarly, Pasteur’s research  eradicated the idea that organisms could spontaneously generate. Using sophisticated apparatus, he prevented microbe-contaminated air from passing into a nutrient broth. This demonstrated that microbes could not be generated spontaneously under sterile conditions.

Louis Pasteur made great advances in microbial research especially when it had industrial connotations. His doctorate thesis was in researching the crystalline structure of two compounds found in fermenting wine, these were tartaric and paratartaric acids. The structures of these two compounds were identical but in solution they rotated polarised light in different ways. Pasteur established that this was due to chirality; he discovered that one structure was the exact mirror image of the other, rather like a left and right shoe. Science has now established that all living organisms only synthesise left-hand amino acids and can only utilise right-hand carbohydrates, left-hand carbohydrate compounds are synthesised artificially. Pasteur suspected that one of the molecules in wine was artificial while the other had been synthesised by a living organism; it was this organism that was responsible for wine fermentation.

During the time Pasteur was researching chirality, alcohol production was thought to be a chemical reaction. Lavoisier had demonstrated that if a sugar solution was dropped on to heated platinum it produced carbon dioxide, water and alcohol. It was therefore reasonably assumed that the production of wine, beer and vinegar was simply caused by a destabilising chemical chain reaction. By transferring some of this destabilised solution to a vat of sugar and grape juice the momentum of the chain reaction would continue. Yeast cells were known to exist in fermenting wine but were just thought to be an incidental byproduct. Around about this time, French wine production was inconsistent because spoilt wine contributed to great economic loss. Pasteur was asked to research a problem concerning lactic acid contamination in beetroot fermentation. Pasteur noticed that whenever fermentation took place yeast cells were present. He also noticed that when lactic acid was produced smaller rod shaped microbes appeared. In addition he observed that compounds other than those formed through the degradation of glucose were present and these tended to be asymmetric.

Louis Pasteur by Albert Edelfelt (1885)

Pasteur deduced that living cells were responsible for wine fermentation and contamination. He also established that if the wine was heated before fermentation commenced then the microbes were killed and the wine remained free from contamination. The procedure of heating to sterilise came to be known as pasteurisation and is today applied to many foodstuffs. One of its most notable applications, and perhaps most beneficial as far as health management is concerned, has been in sterilising milk. Milk as a rich source of protein, was at one time infected by many pathogenic bacteria, including those responsible for common diseases such as tuberculosis and brucellosis. It was through continual development of his knowledge in microbiology and sterilisation methods, that allowed Pasteur to disprove the spontaneous generation theory. Using sophisticated equipment he found that he could physically exclude air-borne microbes from a vessel containing boiled meat thereby preventing contamination His many contributions to science did not finish here he also went on to develop vaccinations against anthrax and rabies infections. The French government funded the Pasteur Institute to allow him to treat rabies victims. His fame transcended the Atlantic were another three Pasteur Institutes were set up.

In 1818 slightly prior to the spontaneous generation experiments conducted by Pasteur, Erxleben put forward a theory that a biological interaction was responsible for fermentation. Renewed interest in this theory led to a number of experiments, in the 1830’s, by Cagniard de la Tour, Schwann and Kützing. They proposed that fermentation was caused by a biological organism that used sugar as a food excreting waste substances in the form of alcohol and carbon dioxide. Many chemists of this period disagreed with this theory, they thought that the fermentation process was entirely physical and did not involve any biological activity. Von Liebig proposed that fermentation was completely mechanical involving a substance that continually processed a chemical transformation causing sugars to degrade into ethanol and carbon dioxide. This argument was resolved by the work of Louis Pasteur. In 1876 Pasteur published a book, Études sur la bière, in which he proposed that microorganisms obtained energy in anaerobic conditions by fermentation. His theories were supported by experimental evidence later supplemented by the work of Meyerhof. The fundamental metabolistic behaviour of yeast is now known as the Pasteur-Meyerhof reaction. There was a brief return to von Liebig’s chemical theories following the discovery that the cell-free juice of yeast extracted by a mechanical press could initiate fermentation. This cell-free juice was called zymase and is now known to consist of enzymes. In fact, the word enzyme, derived from the Greek term for yeast, originates from this discovery. This extract was unstable but still allowed the chemical and catalytic reaction that turn sugar into alcohol and carbon dioxide. It eventually, became generally accepted that this reaction was only sustainable in yeast cells. It was a chemical reaction that provided the yeast cell with the energy of life, life in one of its most simple forms but with a huge impact on the evolution and culture of mankind.

…every living thing is a package of consumable energy

[The Leaven – exploring the relationship between science and religion (cont)]

Although it’s meaning still remains a mystery, Life, in itself, is hard work and requires a lot of energy. It’s now well established that the initial source of this energy is provided by the Sun in the form of light, which is absorbed by a photosensitive pigment called chlorophyll found in plants and other photosynthetic organisms. The energy is then trapped in molecules of glucose, a carbohydrate compound composed by a series of chemical reactions involving carbon dioxide and water. Plant consumers then transfer the energy stored within the glucose carbon source along the food chain. When the glucose is broken down it produces adenosine triphosphate (ATP), the compound required to release the energy that powers most cellular functions. The most efficient way for an organism to synthesise ATP, thereby releasing energy, is by an oxygen requiring process called cellular respiration. In humans oxygen is transferred into the body from the surrounding atmosphere by respiring, it is extracted from air in the lungs by haemoglobin, which is then circulated around the system in the blood.

Chloroplasts visible in the cells of Thyme-moss. Image by Kristian Peters.

As it contains the oxygen required for anaerobic energy production humans cannot survive without blood. Blood was therefore considered of extreme importance in the Biblical era, as it was the substance thought to contain an animal’s character and life force.

Every living thing is a package of consumable energy but not every organism can boast a sophisticated circulatory system that enables cellular respiration. Microbes and other lower life forms have to adopt fairly basic means to generate their energy. The energy generating processes of yeast produces by-products that have been exploited by human civilisations for centuries. One of the ways yeast requires its solar produced energy is by fermentation; a biochemical transformation that converts carbon sources such as glucose or sucrose into energy, producing alcohol, giving off carbon dioxide as a by-product.

Fermentation is not as efficient in producing ATP as aerobic respiration but enables yeast to convert glucose into energy without the aid of oxygen. Scientifically defined, fermentation is a catabolic process that makes a limited amount of ATP from glucose without an electron chain (supplied by oxygen) producing a characteristic end product, such as, ethyl alcohol or lactic acids. During fermentation, yeast not only generates energy from the carbon source but it also breaks it down into an industrially and socially important commodity, namely alcohol. Yeast also has the ability to perform aerobic respiration to give off carbon dioxide but this process does not produce alcohol. Being able to live with or without oxygen is undoubtedly ecologically advantageous to this microbe. Certainly explaining why it inhabited the Earth long before humans did and why it will still be here long after our fragile species has disappeared.

The mysteries surrounding fermentation were once, and to some extent still are, the subject of great scientific endeavour. It was mainly assumed that the reaction was chemically induced because investigators were unaware that miniscule creatures unseen by the human eye could exist. The yeast commercially responsible for transforming carbohydrate rich ingredients, like flour and fruit juice, into loaves of bread or alcoholic drinks is predominately Saccharomyces cerevisiae also known as baker’s, brewer’s or budding yeast. When sugar is plentiful the metabolic route that this type of yeast chooses is fermentation. During fermentation cells multiply rapidly by budding, when all carbon resources are depleted cells either enter a stationary phase of non-division or produce spores. Budding yeasts can also reproduce sexually. Adjacent cells of opposing mating types fuse together, in response to pheromones, by forming protruded structures called shmoos. The end product is a slightly larger round diploid cell that contains two sets of chromosomes; this is a way in which genetic variability is introduced into the cell. This diploid cell can either continue budding or enter meiosis to produce four ascospores.

Performing meiosis is a risky business to budding yeast as it has to temporarily stop increasing population size therefore it only faces this challenge when nutrients are low and its survival is threatened. In this state cells become resistant to stress and can remain dormant for several months, years, decades or even centuries. While dormant they lie at the bottom of the fermenting vessel to form a thick layer of pale brown sediment. Some yeast cells die but many retain the ability to begin dividing again when conditions improve, for instance when more sugar becomes available. This mode of survival allows them to remain viable in the face of adversity.  They are well suited to harsh industrial conditions and, also,  the arid  environment that forms the backdrop of the Biblical Testaments.

…yeast symbolically represents both purity and corruption

[The Leaven – exploring the relationship between science and religion (cont)]

The term leaven originates from the latin word levere, the French equivalent being the noun levure meaning to rise. The English term yeast, probably originates from the Greek term for fermenting which was zestos. Derivatives from later European influences resulted in the medieval English terms zeest, which eventually became yest.

Fermentation procedures and the art of making leavened bread was first introduced by the Egyptians over 4000 years ago. In ancient Egypt, brewing and baking were practiced together on the same premises. Wooden and plaster models depicting Egyptians working in a brewery and bakery have been recovered from a tomb dated around 1975 BC during the reign of Amenemhat I. Egyptian hieroglyphs that show pictures of dough rising next to bread ovens have also been found. The Egyptians were therefore aware that both processes used the same substance.

A funerary model of a bakery and brewery, dating the 11th dynasty, circa 2009-1998 B.C. Painted and gessoed wood, originally from Thebes. Image by Keith Schengili-Roberts

To the Egyptians, bread was an important commodity used as a type of currency for trading and for the payment of services. In fact, the workers who built the pyramids were believed to have been paid in bread. Bread was also used to pay homage to Osiris the God of grain. The Egyptians believed that Osiris had given them the gift of leavened bread to make it lighter to carry, especially in the journey to the afterlife.

In contrast to the Egyptians who revered fermented dough, the ancient Palestinians were extremely suspicious of it. Perhaps this could be due to the different methods by which the bread was leavened. Palestinians would reserve a piece of leavened dough from a previous baking to make the next batch of bread. This dough could easily have been contaminated by harmful microbes which may not have been completely destroyed by the baking processes. If a person died all leaven was thrown out of the house and from all neighbouring houses because Palestinians thought that it may have contributed in some way to the individual’s demise, they believed that the angel of death may have thrust his sword into it.

In Britain during the 15th century, as in ancient Egypt, brewing also took place on the premises where bread was baked. The thick layer of dormant yeast cells that sank to the bottom of the brewing or wine vessel was usually referred to as the lees, while froth from the top of beer was known as barm. Barm from a good batch of beer would be reused to make more beer and to ferment bread dough. Barm, the brewer’s equivalent of leaven, used to be referred to as Godisgoode because it was thought to be a gift from God. Yeast used in brewing and baking seemed to be received in a different manner to leaven that was used to make sourdough. In fact during the 17th century the Paris Faculty of Medicine tried to ban leaven because in the New Testament St. Paul had signified that it was a substance that denotes corruption.

So it seems that fermentation generated through leaven was not viewed in the same way or as a similar process to the fermentation that produced wine. It is clear from passages in the Bible that leaven is used figuratively to symbolise the permeating influence of certain types of human behaviour, especially corruption. Traditionally unleavened bread is used to symbolise the purity of Christ’s body whereas wine symbolises the blood of Christ. This is not without some irony, as wine is made in a similar process and perhaps more likely to lead to acts of sin and corruption when consumed than is bread. Indeed, some religions do recognise this and at the beginning of the 20th Century, alcohol became prohibited for a time in a number of Nordic countries and North America due to Protestant led objections. Alcohol is also prohibited in some countries that follow Islamic laws. The contradictory views relating to fermentation in wine and bread will be discussed at greater length in a later chapter.

The molecular, vegetative animalcule

[The Leaven –  exploring the relationship between science and religion (cont)]

Yeast is a domesticated organism that has become almost indispensable in modern society. Although unessential to the staple diet, supermarket shelves are crammed with products that require yeast fermentation. Bread, chocolate and alcohol production all involve the metabolic activity of these simple single-celled microbes. Restaurants, bars, clubs and many aspects of social behaviour revolve around yeast products.

Throughout the centuries yeast has been the focus of domestic and industrial life. While it’s fermenting ability has  been the focus of many different hypotheses and paradigm shifts. Fermentation was once thought to be the consequence of a chemical reaction by some kind of substance and not the metabolic activity of a living organism. During the Biblical era there would have been no conception that the metabolic pathway of a microscopic bug was the source of fermentation.

Yeasts are naturally abundant in the environment especially in the soil where they are transferred, by insects or other means, on to the skins of fruit and animals, including humans. The environment contains many different types of yeast, from those that cause fungal infection (Candida spp.) to others that are used in the baking industry and in wine-production (Saccharomyces spp.). Yeast belongs to the kingdom Fungi and the division Ascomycota. In recent times it has become a major player in biological research and is now one of the most studied organisms on Earth. It was the first eukaryotic organism to have a fully sequenced genome. The majority of its genes have been researched and functionally analysed and, as many of these have analogues in other multicellular organisms, it is therefore possible to study molecular processes from mammalian systems within a unicellular model eukaryote. It is also well established as a favourable alternative to animal model systems.

Large-scale experiments involving computers, robotics and new molecular techniques, such as polymerase chain reaction (PCR) to amplify genes and DNA micro-arrays, that arrange hundreds of these genes onto a small grid, have generated such a large amount of data that new scientific disciplines, eg., genomics, transcriptomics,  have evolved in order to process it all into meaningful results. The simplicity of the yeast life-cycle has made it invaluable to medical and biotechnological research. Certainly, yeast has had a great impact on 21st century society that has inflicted on social behaviour and medical research. Anthropology would have evolved differently if this organism ceased to exist.