A look at the history of yeast
We have had a relationship with yeast for thousands of years, and yet, we have narrowed down and genetically modified single microorganisms to function in specific ways that lead to the development of today’s modern mass bread manufacturing processes. So, how did we get from a natural fermentation process that was understood and used on a daily basis by the general population in biblical times to fast acting commercial yeast that enables the modern mass production of bread today and how do we get back to the way bread used to be?
The word "yeast" comes from a combination of Old English “gist,” or “gyst”, and Indo-European “yes” which meant to "boil" or "foam”, and for thousands of years bakers have understood what it does. There is evidence of the mastery of wild yeast and its use in bread-making 4000 years ago in Egypt. William Sitwell’s “A History of Food in 100 Recipes” discusses early bread making in ancient Egypt including early depictions of bread showing how “people had progressed in agriculture and the techniques of milling, leavening and baking”. Sitwell includes hieroglyphs from tombs near Luxor illustrating bread making and he notes that there is evidence of “bread being left to rise near ovens”. Beer making in the same hieroglyphs suggest that the Egyptians had found though the air-borne yeast spores that “the baker enjoyed the resulting fluffier loaf” although “the products of this early baking were most likely like modern day pitta bread”.[caption id="attachment_1925" align="alignleft" width="702"] Yeast by William Jago[/caption]
Move forward 2000 years and the use of wild yeast was an everyday occurrence. There are innumerable references to leaven in the Bible (Matt.13.33) “The kingdom of heaven is like yeast that a woman took and mixed into a large amount of flour until it worked all through the dough”. The use of yeast and leaven in parables as a tangible metaphor for the explanation of the idea of God clearly demonstrates just how everyday the art of fermentation had become.
Although yeast had been used for thousands of years, the science of its mechanics wasn’t understood until 1680 following brewer’s son, Antonie van Leeuwenhoek’s devotion to the manufacture of microscopes and his first observation of yeast globules.[caption id="attachment_1926" align="alignright" width="230"] Yeast Advert 1930[/caption]
By the 18th century, the relationship between bakers and brewers was firmly established, and the main source of yeast for almost all professional bakers was beer barm. As the title of James Stone’s 18th century pamphlet suggests, barm (the yeasty froth on the top of fermenting beer) was considered precious, and yet it was not always well understood, “The Complete Baker; or a Method of effectually raising a Bushel of Flour, with a Tea-Spoonful of Barm: Intended to obviate the great Difficulties Bakers are often put to, for want of a Quantity of Barm, that very necessary Ingredient in making of Bread. In which is likewise shewn, that the Cause of Bread being close and heavy is entirely owing to the Baker being unacquainted with the Nature of Barm and Flour”. The term “barm” was applied equally to yeast-leavened bread, without implying the use of sourdough or barm leavens. The relationship between bakers and brewers had been going on for hundreds of years, but by the early 19th century there was a move away from beer barm (its unpredictability gave us the expression “barmy”) and reliance upon the local brewer declined. In “A New System of Domestic Cookery” (1824) there is a recipe for Mrs Rundell’s yeast. Rundell wrote for the housewife and published this recipe for yeast to enable women to make their bread with homemade yeast.[caption id="attachment_1927" align="alignleft" width="200"] Microscope[/caption]
MRS RUNDELL’S YEAST
Thicken two quarts of water with fine flour, about three spoonfuls; boil half an hour, sweeten with near half a pound of brown sugar; when near cold, put into it four spoonfuls of fresh yeast in a jug, shake it well together and let it stand one day to ferment near the fire without being covered. There will be a thin liquor on the top, which must be poured off; shake the remainder, and cork it up for use. Take always four spoonfuls of the old to ferment the next quantity, keeping it always in succession.
A half-peck loaf [based on 7lb of flour] will require about a gill [i.e. ¼ pint].
Despite homemade yeast being readily achieved, the use of beer barm for proving bread did not fade entirely. Beer barm was well documented as the main source of yeast in the Canadian Settler Guide (1855). With detailed advice on curing brewers yeast for bread making purposes and instructions on how to alleviate the bitterness from the residual hop oil, the use of leaven was no longer well understood by everyday folk. One such story in the Settler Guide confirms this telling the tale of a neighbour who was “astonished at the ignorance of both a mistress and her maid” and whom she showed how to make yeast remarking that “this valuable piece of knowledge stood them in good stead: from that time they were able to make light bread: the girl shrewdly remarking to her mistress that a little help was worth a great deal of pity”.
It was not until 1857 with the work of French scientist, Louis Pasteur, that the fermentation process was understood. Pasteur believed that the agents responsible for fermentation were yeasts and it was Pasteur who established that yeast was alive and is the microorganism that plays the key role in fermentation. Hansen in 1888 then went on to confirm that that yeast could be isolated and propagated in pure culture. This was a turning point in the history of yeast, and shift began from the use of wild yeast and beer barm as the main source of yeast by bakers in the UK.[caption id="attachment_1928" align="alignleft" width="205"] Yeast by William Jago 1895[/caption]
In the late 19th century, with the Industrial Revolution well underway, the logical next step was for large-scale, consistent yeast manufacture for mass production. Rapid scientific advancements lead to huge strides in the understanding of yeast and in 1876 two brothers, Charles and Max Fleischmann, used the Centennial Exposition in Philadelphia to introduce their new manufactured yeast to an audience of over 10 million visitors. Their innovation was an immediate success and by 1900 they added a state-of-the-art research laboratory to their New York plant.
In the 1930s yeast was discovered to be an excellent source B vitamins, and there is plenty of evidence that yeast manufacturers extolled the heath benefits and virtues of using yeast and baking at home – with some creativity. From curing hair loss to helping with constipation, the yeast manufactures encouraged people to use it to bake with in place of baking powder. Commercial yeast was firmly established as a household essential and new yeast hybrids were developed through conventional cross breeding began. Winge and Laustsen (1938) were the first to produce new yeast types by recombination of existing variations between commercial strains.
In the 1940s as the US entered the war, Fleischmann Laboratories still lead the way in developing yeast. They discovered and then manufactured Active Dry Yeast®, specifically to ensure that the troops could enjoy home-baked bread. Until this point, all yeast was fresh. Unlike compressed fresh yeast, the new yeast did not require refrigeration and was activated quickly with warm water. It was a revolution in baking. As laboratories started to develop yeast further, new highly active dried yeasts were developed capable of raising dough up to 50% faster than regular active dried yeasts. In 1961, this leap lead to what is now considered by many to be the low point of bread making - the high volume Chorleywood bread making process. The Chorleywood Process is a continuous industrial method for making bread in a factory, where speed and cost is of the essence, leaving flavour and texture far behind.
Elizabeth David in “English Bread and Yeast Cookery” (1977) noted that “Bakers’ yeast as we now know it is manufactured only in factories specializing in production of this particular type of yeast on a massive scale. Originally, when the distillation of baking yeast was first developed in the mid nineteenth century, the basis was a wort or infusion of grain – wheat, rye, malted barley – or of potatoes and sugar. Nowadays bread yeast is nearly always grown on a solution of molasses and water, the process by which it is produced being highly automated and controlled from the laboratory rather than in the distillery itself”.[caption id="attachment_1934" align="alignright" width="200"] Ambrose heath on cooking with Fresh yeast[/caption]
Modern day yeast is now big business. It is a microbe with annual worldwide consumption exceeding 1 million tons. The applications for yeast have gone far beyond brewing and bread making as yeast is being used in the pharmaceutical industry and beyond. In 2008, US scientists developed a way to produce a group of medically important plant compounds in yeast. The findings showed how certain strains of yeast could be used to manufacture drugs including painkillers and new cancer treatments inexpensively.
Today, commercial yeast manufacture for bread making is divided into four basic steps: the use of molasses and other raw material preparation; culture or seed yeast preparation; fermentation and harvesting and filtration and packaging which sounds straight forward, until you ask yourself, which yeast stains are being made and how does that yeast affect the bread that I bake and eat? Fast rising bread gives no time for flavour to develop naturally. As the development of fast acting commercial yeasts were manipulated to satisfy the demands of the modern baking industry, there have been numerous and extensive programmes for strain development of S.cerevisiae (Baker’s yeast), many of which have taken place using genetic manipulation technology. As laboratories have advanced and developed commercial strains, many have been patented and several yeasts using DNA modification are registered with the National Collection of Yeast Cultures in Europe.
Frederick T. Vine “Practical Breadmaking” (1897), wrote “The flavour and sweetness of your bread depends in so great a measure upon the yeast used in its manufacture that I must claim your indulgence if I seem to treat it at undue length.’
I agree with Fred. Fresh yeast gives better flavour than dried. Despite dried yeast having the practical advantages of keeping for months or even years, I keep coming back to fresh yeast for flavour. It is fresh yeast’s connection to the past that also appeals to me, and there is a romance in baking bread the way it used to be. Yet, accounts of bread and how used to taste suggest that really good bread was, in some parts of Britain, a rare thing. Owen Simmons “The Book of Bread” (1886) analysed various breads from bakeries across the whole of England, Scotland and Wales. The reports on bread in my home county of Northamptonshire showed that the standard of my local bread was appalling. A bread made with 8oz of malt extract and 8oz of yeast Simmons described as “A miserable loaf – to be guarded against. Worst seen for a long time. Poor flour, poor process, poor skill”. Another local baker’s bread was likewise described as “Poor loaves, overworked. Bad flavour, bad smell and cold oven largely contributed. Sponge too long”. Other loaves ranged from atrocious, sour, pasty and discoloured. Fortunately elsewhere some were described as beautiful or excellent, but finding good bread at the end of the 19th century was hit and miss.
With no regulation of any kind until 1875 there were few effective controls on the content or quality of food and drink on sale to the public. Some of the commonly used additives added to bread in the 19th century were actually poisonous. To whiten bread, bakers sometimes added alum and chalk to the flour, while plaster of Paris (calcium sulphate), mashed potatoes, pipe clay and even sawdust could be added to increase the weight of loaves. Dried, powdered beans were commonly used to replace wheat flour and the sour taste of stale flour was then disguised with ammonium carbonate and “by the beginning of the 19th century the use of such substances in manufactured foods and drinks was so common that town dwellers had begun to develop a taste for adulterated foods and drinks”, Royal Society of Chemistry, “The Fight Against Food Adulteration” (2005). I think it is fair to say that the idea of trying to get back to the way bread used to be is rather dependent on which bread it used to be. In truth the idea that all traditional old bread was good is a myth, so perhaps trying to get back to the way bread used to be is not the way forward.
So in the end does it matter in the end what kind of yeast I use? Yes. The kind of yeast I use certainly does matter. I make bread because I love taking control of something fundamental in my life. I like the connection to the past and to feel, touch and taste bread that is mine, so the idea of using genetically altered chemically altered yeast doesn’t appeal to me as a home baker. I can see it has an important role in industrialised bread making, but in my home I want to use natural strains of yeast that haven’t been manipulated to behave in a way that suits commercially produced bread.
What it comes down to in the end is that the smell of fresh yeast is good. It is lively and slightly fungal, and I love to feel the yeast between my fingers, and like many bakers I feel more in touch with my bread when I bake with fresh yeast. Fresh yeast brings out the artisan in me, but not all fresh yeasts are equal; so I prefer to bake with organic yeast, where the fermentation process uses natural organic ingredients for my bread. The longer slower natural fermentation process develops full flavoured traditional bread that has all the advantages of modern ingredients. It is bread at its best, which, I think, is what every artisan bread maker wants.
- William (2012), A History of Food in 100 Recipes Sitwell. Collins.
- David, Elizabeth (1977), English Bread and Yeast Cookery. Allan Lane.
- Vine, Frederick (1897), Practical bread-making. Published in London.
- Stone, James (1770), The Complete Baker; or a Method of effectually raising a Bushel of Flour, with a Tea-Spoonful of Barm: Intended to obviate the great Difficulties Bakers are often put to, for want of a Quantity of Barm, that very necessary Ingredient in making of Bread. In which is likewise shewn, that the Cause of Bread being close and heavy is entirely owing to the Baker being unacquainted with the Nature of Barm and Flour. Salisbury.
- Trail, CP (1855), Canadian settlers guide. Published in Toronto.
- Sturely and Young (2005), Genetic Manipulation of Commercial Yeast Strains,
- Royal Society of Chemistry.
- Rundell, Marie (1808), A New System of Domestic Cookery. John Murray, J. Harding, and A. Constable and Co., London.
Simmons, Owen (19