The ratios play a very important role in brewing. They define the proportions between the raw materials and the finished beer, or between the raw materials and the intermediate products needed for brewing. These grains-to-beer proportions vary according to the type of beer, its density and the nature of the raw materials used. Schematically, the brewing ratios are as follows:
|Volume of raw material||Volume of brewed beer||Ratio||King of beer|
|100 liters||50 liters||2:1||Strong beer|
|100 liters||100 liters||1:1||Average beer|
|100 liters||200 liters||1:2||Weak beer|
The industrial brewery is based on the setting, measuring and strict control of extremely detailed ratios. This reproducible process approach makes it possible to brew ranges of beers whose sensitive characteristics fluctuate very little.
Nowadays, thousands of beer recipes are circulating among amateur brewers. They are based on proportions whose values characterise a type of beer, in addition to the nature of the ingredients.
The technique of brewing ratios appeared very early in the history of beer. Mesopotamian, Egyptian, Chinese or Indian brewers mastered this technical approach. From the beginning of the 3rd millennium BC, Sumerian brewers wrote the technical details of their brews on clay tablets. The oldest written documents are relatively complex accounts drawn up by brewers, more precisely managers of beer-making workshops. They are responsible for the volume of grain or brewing ingredients (malt, beer breads, baked loaves) supplied to them to brew beer and the volumes of beers of various qualities that they have to deliver. Example: with 500 litres of grain, the brewery manager can deliver 100 litres of top beer, 200 litres of standard beer and 200 litres of lower quality beer according to the ratios given above.
This arithmetic seems extremely simple. In brewery practice, the management of ratios is more complex. Not all brewing ingredients are equal, even if they are all counted with the same volume measure. A litre of barley and a litre of starch wheat do not provide the same amount of starch. The same is true if you compare raw grains, malt or beer breads.
These specialised managers scrupulously record the volumes of raw grain, wafers, beer bread and malt used to produce such and such a volume of such and such a beer. The raw materials (raw grains), as well as the intermediate products (malt, loaves, beer bread), are perfectly defined and quantified. The quality of the beers, of about 4 or 5 kinds, is specified. The brewed volume of each is given. We have brewery accounts that are based on explicit ratios. Because from one tablet to another, certain grains-to-beer proportions are repeated. This is the major innovation of this ancient age.
5000 years ago, the novelty was no longer knowing how to make beer, nor how to calculate the volumes of this or that brewing product. The novelty is the invention of the control of each brew by means of ratios. Mesopotamian brewers developed recipes to reproduce, day after day, the same kinds of beer. The study of these ratios and the brewing techniques that go with them allows us to understand the logic behind this invention. It is, as often happens, the technical answer to a question of an economic and social nature. How can different kinds of beer for different social categories be produced with regularity?
One of these uses is the highlighting of social hierarchy. The social rank of each person should be read in the category of beer he or she drinks. This social quality is expressed precisely by a ratio between the volume of grains and the volume of beer. At the bottom of the social hierarchy is a ratio of 0.5:1, which reads half as many grains as beer. For a middle social rank, a 1:1 ratio means as many grains as beer. The higher you go up the social hierarchy, the higher the proportion of grains used per volume of beer, 2:1 to sometimes 3:1.
Another use, economic this time, is the system of maintenance in kind of persons subordinate to a temple, a palace or any economic entity. It is based on the distribution of the bare necessities of food, beverage and clothing. Beer was at that time the main beverage in the rations, which were all calculated according to their gross grain equivalent. The brewer must produce strictly calibrated beers: this volume of beer = this volume of grain. This means that the brewer must control the ratio of his brews for this type of beer.
These social logics are translated into controlled brewing methods in various cultures. The logic of ratios is general enough to adapt in antiquity to different technical brewing schemes. To date, there are 4 files available to describe and verify the logic of the brewing ratios:
- the Mesopotamian records: from the 3rd millennium B.C. onwards, it consists of several chronological sub-folders up to the end of the 2nd millennium.
- the Egyptian records: brewing ratios and mathematical exercises from the Middle Kingdom.
- the Indian records: beer recipes in India from the Maurya empire founded around 322 BC.
- the Chinese records: beer management in Dunhuang between the 7th and 10th centuries AD under the Tang dynasty (618-907).
These studies are currently being published.