English Nut Brown Beer
Meistr Madoc Arundel, OL
Beer styles as we know them today are, by our reckoning, a modern determination. We do not see clear definition of classic beer styles until the mid to late 17th century, and then only a few differentiations. This is not to say that there was not an understanding of beer styles within our period of study – there was. It is just to say that the definition of an English Nut Brown style is not a true period example. That being said, the concept of a brown beer is well known if only marginally documented in our period of study. For the purpose of this paper, I am using the generally accepted definitions of beer and ale, whereby ale is a malt beverage made with herbs and spices while beer is a malt beverage made with hops, rather than the modern definitions determined by the use of top or bottom fermenting yeasts.
Ale is made of malte and water; and they the which do put any other thynge to ale than is rehersed, except yest, barme, or goddesgood, doth sophysticat there ale. Ale for an Englysshe man is a naturall drinke. Ale muste have these properties, it muste be fresshe and cleare, it muste not be ropy, nor smoky, nor it must have no wefte nor tayle. Ale shulde not be dronke under .v. dayes olde …. Barly malte maketh better ale than Oten malte or any other corne doth … Beere is made of malte, of hoppes, and water; it is a naturall drynke for a Doche man, and nowe of late dayes it is moche used in Englande to the detryment of many Englysshe men … for the drynke is a colde drynke. Yet it doth make a man fatte, and doth inflate the bely, as it doth appere by the Doche mennes faces and belyes.1
The first English documents cited by the OED in which the term beer signifies the hopped beverage are customs records of the 1390's. One of them, interestingly enough, is for Margery Kempe's town of Lynn, where barrels of beer imported by alien merchants from the low countries were taxed. Margery herself records what must be among the earliest instances of hopped beer consumption in English literature.2
The process of malting grains for brewing was known for centuries.
...the Greeks ascribed the invention of malt to the Egyptians. The art of malting, the key to successful brewing, is thus one of the most ancient of processes. The art found its way from Egypt to Tyre and Sidon and thence to Carthage, Greece, Rome, Germany, Gaul, the Scandinavian countries and to Britain.3
Essentially, malting consists of allowing grains to germinate to a certain point, followed by the application of heat to halt the growth and kill the sprouts. What was left in the grain was a combination of convertible starches, amino acids, and amylase enzymes which enabled the mashing process – the production of fermentable sugars.4 We know that this process was well established by the time of Charlemagne by looking at the plans for construction of the St. Gall Monastery c.820 AD. The plans called for three separate breweries, a granary, a mill, and a kiln for the production of malted grains.5
Kilns used for drying the malt were primarily fired by wood, straw, or peat. Depending on the logistics of the kiln itself, the quality of the fire, and the proximity of the grains to the heat source, the individual grains might be lighter or darker. In earlier periods, these grains would not have been separated out by color, but would simply have been used collectively. This would have resulted in a beer of color anywhere from a pale amber to a rich brown. Since beer styles were not defined to the level of detail they are today, color would have been largely dictated by individual kilns within each locale. However, by the mid to late 17th century, recognition of the differences between various roasts of malt was common. “...it then must be put on the Kiln to dry four, six, or twelve Hours according to the nature of the Malt, for the pale sort requires more leisure and less fire than the amber or brown sorts.”6
“Colored malts resulted from uneven heat control which would have produced pale, amber and brown malts in the same batch, and likely in random distributions. Brown malt was also intentionally produced to reclaim slack malt.”7
For this recipe, I used a combination of 80% pale malt (3L), 15% crystal malt (40L), and 5% chocolate malt (475L) in order to emulate the odd mix of various roasts more common in the 15th and 16th centuries.
Hops was a well known agricultural product in Europe by the 9th century. Records from two French abbeys, St. Germain-des-Pres and St. Remi, both show sizable quantities of hops brought in from a number of estates.8 In this case, it was largely used for medicinal purposes, having a mild analgesic effect as well as being purported to induce sleep.
The first documented link between hops and brewing comes from Picardy in Northern France, in 822, where Abbot Adalhard of the Benedictine monastery of Corbie, in the Somme valley near Amiens, wrote a series of statutes on how the abbey should be run. The many rules covered areas such as the duties of the abbey’s tenants, which included gathering of firewood and also of hops – implying wild hops, rather than cultivated ones. Adalhard also said that a tithe (or tenth) of all the malt that came in should be given to the porter of the monastery, and the same with the hops. If this did not supply enough hops, the porter should take steps to get more from elsewhere to make sufficient beer for himself.9
A German abbess named Hildegaard living in the abbey of Rupertsberg near the town of Bingen-am-Rhein documented hops use in beer in Physica Sacra, published c.1158. Her treatise is the first indication we have of hops being used for its preservative qualities rather than simply for flavoring.
It is warm and dry, and has a moderate moisture, and is not very useful in benefiting man, because it makes melancholy grow in man and makes the soul of man sad, and weighs down his inner organs. But yet as a result of its own bitterness it keeps some putrefactions from drinks, to which it may be added, so that they may last so much longer.10
There is a reference to continental ale appearing in England in the city of Norwich as early as 1289 AD, albeit in extremely small quantities. “Of Richard Somer because he sells Flanders ale privily, whereby the bailiffs have lost custom, 2s.”11 Many early references to the import of continental hopped beer do not appear in England until nearly a century later.
Henry Vandale bought four barrels of “beere” in London in 1372. A ship’s captain named Clays Johanson arrived in London in July 1384 with a cargo that included earthenware dishes, Holland linen cloth and beer. Other records of beer imports in the late 14th century come from Newcastle, Scarborough, Lynn, Ipswich, Winchelsea and Sussex. At the end of the 14th century Great Yarmouth was importing 40 to 80 barrels of beer a month, while in 1397-8 Colchester imported 100 barrels of beer.12
There are numerous anecdotal claims of when the first hops cultivation was established in England. Sources range from 1511 to 1569 as the 'accepted' start date. We know that Henry VI brought over experts from the low countries as early as 1549 to advise English farmers about the cultivation of hops. The privy council of England determined on “Tewsday, the xviijth of February, 1549...Warrant to <name> for cxlli to <name> for charges in bringing over certain hopsetters.”13
We can also be reasonably certain that hops cultivation was well established in the areas around Kent and Sussex by 1589. A very detailed explanation of the best time to plant hops and the best methods for ensuring a good crop are described in his treatise on planting and grafting of agricultural products.14 Mascall goes on to explain how to prepare the hops for use in the brewery.
When your Hoppes be well tossed and turned on boorded floores, and well dryed (as I haue afore shewed) ye shall put them into great sackes according to the quantitie of your Hoppes, and let them be troden downe hard togither, which will kéepe their strength longer, and so yée may reserve them, and take at your pleasure. Some doe use, (which have but small store) to treade them into drie fattes, and so reserve them for their use, which is counted the better way and the lesse portion doth serve, and will longer kéepe their vertue and strength.15
The town of Buxted in Sussex has a church dedicated to Saint Margaret the Queen, where “Hop flowers decorate the sides of this ceiling, which is said to have been installed in 1600 by the rector of the day, in gratitude for a fine crop of hops.”16
Hops contain two types of acid – alpha and beta. The alpha acids contain the chemical agents Humulone, Cohumulone and Adhumulone and are used to impart bitterness. Alpha resins are not very soluble and must be boiled extensively to impart bitterness in the beer. Beta acids are used to impart flavor and aroma. Unlike the alpha acids, these oils are water soluble and will quickly boil off. Typically, hops will impart flavor if boiled between 5-15 minutes and aroma if boiled for 1-3 minutes.17
For this beverage, I used Kent Golding hops (~6% Alpha) for bittering, and Fuggle hops (~4% Alpha) for both flavor and aroma. Both strains of hops are cultivated in the Kent/Sussex area of England.
Although yeast as a microbe was not known until the early 19th century, yeast itself was known earlier than the days of the Roman empire. Recognized as both the froth that rose to the top of the fermenting vat and the sludge that fell to the bottom, its cause may not have been well known but its effect was certainly common knowledge among both brewers and bakers.
The traditions of brewing were carried on and thrived under the Catholic Church. Nearly every major monastery in medieval Europe contained a brewery that served not only the monks but also pilgrims and the surrounding villages (perhaps as an inducement for attending mass). One large monastery in Switzerland had three breweries, each adjacent to a bakery. Brewing and baking, in fact, were closely related activities in ancient and medieval times.18
The presence of an agent for fermentation was known at least in France in the 13th century. In a comprehensive law enacted by Louis IX in 1268, numerous strictures to ensure the quality of fermented beverages are laid out, including regarding the sale of yeast barm. “No beer yeast shall be hawked about the streets, but shall be all sold in the brew-houses to bakers and pastry cooks, and to no others. Beer yeast brought by foreigners shall be inspected by a jury before it is exposed to sale.”19
Spontaneous fermentation was undoubtedly the result of natural yeasts found in the atmosphere, or exigent on the leaves and skins of various ingredients added to provide flavor. Dominant strains of wild yeast in any locale would have been the primary means by which yeast made it into the fermenting vessel.20 Wild yeasts by their very nature are aggressive, highly tolerant of a hostile brewing environment (able to survive in more extreme temperatures or in a high-alcohol beverage), and more likely to produce what we would today call 'off flavors'.
Spontaneous fermentation—what I am hereby referring to as nothing short of “immaculate”—is an age-old practice, first by accident and then by intention, that truly puts Mother Nature at the helm of brewing magic. This type of fermentation takes place when ales are fermented with wild yeasts—from an open window, for instance, or already residing in a barrel...21
Before the advent of refrigeration and advances in the science of fermentation in the mid-nineteenth century, almost all beer was, to varying degrees, sour. The culprits were pre-modern sanitation and poorly understood, often naturally occurring bacteria including Lactobacillus and Pediococcus, as well as Brettanomyces yeasts, which can contribute a hint of tartness and characteristic 'funky' flavors and aromas, sometimes compared to leather, smoke, and 'horse blanket.'22
Relying on airborne yeasts, brewers virtually never got a distinctly high or low fermentation variety but rather something mixed. The method worked but was haphazard and raised the risk of infection from unwanted yeast strains which could ruin the beer.23
However, the same bed of yeast may be cultured from batch to batch in an effort to modify the yeast to recognize and react to the ingredients of a particular recipe. In this rudimentary culturing process, the yeast will evolve slowly with each new batch, producing a predictable set of qualities in the finished beverage. The medieval brewer would facilitate this culturing by scraping the foam layer from a currently fermenting batch or by setting aside the lees from the bottom of the fermenter in order to use it to 'start' the next batch.
When flowers and other leafy herbs or fruits were added to the brew it almost certainly provided necessary yeasts; for yeast, as such, was not an ingredient of itself. The people of the Middle Ages knew that yeast was necessary but didn’t quite understand where it came from. The barm (yeast froth) was scraped off the top of the fermenting beer, saved and used to make bread or promote the next batch of brew.24
Some brewers did, it seems, recognize the possible infection of their brews by airborne yeast, a situation first mentioned at Munich in 1551. The realization was slow in coming, however. As early as the mid-fourteenth century a Flemish recipe book mentions adding yeast to beer, and it seems likely that already by 1300 brewers were using some of the foam skimmed off the top of the fermenting beer of the last brew to start fermentation with the next one. By the sixteenth century, brewers commonly added yeast to wort from cultures which they kept separate and which they controlled and maintained. Regulations in Harlem in 1519 and 1550 leave no doubt that brewers added yeast once the wort was in the fermenting troughs.25
The greatest example of culturing yeast from batch to batch comes to us from the Trappist breweries of Belgium – coincidentally the same regions that provided most of the first hopped beers to be imported to the British Isles. Of the remaining ten Trappist abbeys that produce beer, two date to our period: the Brasserie d'Orval in the Gaume region of Belgium, and the Abbey of Notre Dame de Saint-Remy near Rochefort. The Rochefort beers have been brewed with the same strains of yeast being cultured forward batch-to-batch since 1595.26 Although the current Orval brewing facility only dates to 1931, the original brewery dates back to at least 1628, based on writings from the abbot at the time.27
On a side note, in addition to the boiling of water for the mashing process and the natural contrabacterial qualities of hops, the yeast itself contributes something to the sanitary nature of beer.
If the beverage contains viable yeast cells these will ensure that anaerobiosis is maintained and so inhibit the growth of aerobic contaminants. Further antiseptic qualities are introduced by many of the supplementary flavouring agents, for example, hops... In historical times, therefore, beer was a useful source of dietary calories, minerals and vitamins but could also be viewed as sanitised water. In medieval times this property was of no small significance when one considers the number of potentially fatal diseases which could be contracted after imbibing polluted water. This is illustrated by the story of Saint Arnold,the patron saint of Belgian brewers, who reportedly saved the inhabitants of a village gripped by a cholera epidemic, by blessing the local brewery and advising them to eschew water and from then on drink only beer.28
For this particular batch, I pitched yeast that I have been carrying forward from multiple batches. The original strain I used was a Danstar Windsor strain from Lallemand laboratories. I used the lees from the original batch three times, each time in a brown ale, with this project being the fifth batch (fourth carryover.) It is reasonable to assume that the yeast has by this time taken on some of the characteristics of the brown ale recipe.
The basic process for brewing beer has not changed significantly since the middle ages. Malted grains are cracked and soaked in hot water to convert starches to fermentable sugars, then drained and rinsed to extract the malt liquor. Flavoring agents such as herbs, spices, hops, fruit, etc. are added, and the brew is allowed to ferment until ready to package or drink. The major differences occur in three stages.
The first is that medieval brewers would have extracted the first run of liquor for a batch of strong beer, and sparged a second running for a batch of 'small' or weaker beer, while modern brewers will sparge both runnings into a common batch. “Brewers discovered early on that they could add water a second time to the mash tun and get a weaker beer from the same grain.”29
Try doing a Medieval style double mash (mash, draw off the liquid, mash again and draw of the liquid) and you will get two brews. One, a strong ale with OG around 1.075, and a small beer with OG in the mid to upper 1.030s... The strong ale could be stored and the small beer was for everyday family use... We sparge so we can use minimal ingredients and get the same effect as our ancestors got from a second running of their mash.30
The older practice, described in later brewing guides and certainly used in the Middle Ages, was 'parti-gyle' brewing, which involved drawing off the wort before adding more water to the grain, making a second, sometimes even a third infusion. Each infusion was naturally weaker than the previous one, and they could either be recombined, or used to make drinks of different strength.31
For this batch, I did a single stage mash using 10 pounds of grain in 6 gallons of water at 155 degrees Fahrenheit for 90 minutes. I sparged with another 2 gallons at 175 degrees Fahrenheit. My total volume at the start of the boil was just under 7 gallons, which included both the strong and small runnings.
The second is that the boiling of the wort would not necessarily have occurred in the middle ages once the malt liquor was extracted. Most of the flavoring agents would have been added directly in the fermenting vessel, similar to the modern practice of dry hopping. Certainly, the addition of hops to the recipe would have resulted in boiling the wort at some point in history, since the oils in hops would not be broken down to provide the bittering without a certain amount of boiling time.
For an ale, the wort, the liquid containing sugars and protein extracted from the grain, was not boiled prior to fermenting. For a beer, the wort had to be boiled with the hops. This seemingly small difference was in fact a change in technology that had long-reaching consequences for the preservation, as well as taste and nutritional value of the beer.32
That being said, we see evidence of boiling of the wort as early as the time of Charlemagne. Regarding the design of the monastery at St. Gall:
Each brewhouse was divided with a hearth house for brewing and a smaller cooling room. In each, there were four ranges for heating water and boiling wort. The design of the stoves in the breweries was exactly the same as that of the stove in the monk's kitchen. Around the stoves were four wooden vats, or possibly metal cauldrons, for mashing. There were two vats along an aisle for cooling beer once brewed and, presumably, also for fermentation.33
For this batch, I boiled for 60 minutes, reducing the overall volume of my kettle to approximately a third over 5 gallons. I added the bittering hops at 45 minutes remaining, the flavor hops at 15 minutes remaining, and the aroma hops at 2 minutes remaining.
Lastly, while modern fermentation is largely anaerobic (occurring in a closed vessel), period fermentation would have been largely aerobic (occurring in an open fermenter or a porous container such as a wooden cask or clay amphora.)
“During medieval times wooden tubs or vats with open tops were essentially the universal fermenting vessels and remained in vogue almost until the nineteenth century. Some of these containers appeared to have several hundred gallons of capacity.”34
The records state in 1601 that in The Cloverleaf in Amsterdam the wort was transferred to the tun from 'the cooling vessel on the south side' via a long channel. Sometimes a pump was required. The Delft Arms for example had 'two cooling vessels with channels and a pump'. This Amsterdam brewery also had a 'fermenting tun with a central partition' which could be used for smaller quantities... Yeast was added separately to every brew; Haarlem records of 1550 mention this practice. The yeast was stored in a special jug. One of these 'yeast measuring jugs' was included in the inventory of The Delft Arms in 1604.35
One option used was to move the beer into smaller containers, like barrels, after the first two or three days. Whether fermentation went on in troughs or in casks, one goal was to keep down the amount of air available to the beer. Pieces of rough paper put in the bung holes before tapping in the bungs kept air out of the casks. Another way to get the same effect was to use deep fermenting troughs so that only a small amount of the beer had a surface exposed to the air.36
Primarily based on cost, I do not currently own the equivalent of period fermentation vessels. However, in an effort to emulate the period practice while still adhering to my deeply held convictions regarding contamination, I took the following steps. I allowed primary fermentation to take place in a food-grade plastic bucket covered with a towel. Primary fermentation ran 5 days. Once the foam layer began to subside, I transferred the wort into a 6-gallon glass carboy with an airlock to continue the secondary fermentation cycle. By the end of the fourth week, the fermentation cycle appeared complete, and the beer had nearly cleared, leaving a little over 1¼ inches of sediment in the bottom of the carboy. I harvested the sediment for use in starting my next batch. I kegged the beer in a 5-gallon Cornelius keg, and force carbonated it with 12 pounds of pressure to simulate the low carbonation level expected of beers kept in wooden casks.
1Boorde, folio Gii-iii
3Brookes, pg 26
4Palmer, pg 141-142
5Unger, pg 27-29
6Fox, pg 11
8Unger, pg 54
10Von Bingen, Book I, Chapter 61
11Hudson, pg 364
13Great Britain Privy Council, pg 395
14Mascall, pg 86
15Ibid, pg 89
16Spence, pg 287
17British Brewer, Hops
19Salem, pg 19
23Unger, pg 152
25Unger, pg 152
27Saint Peters List
28Boulton, pg 6-7
29Unger, pg 17
33Unger, pg 28
34Hardwick, pg 50
35Kistemaker, pg 70-73
36Unger, pg 153
Babor, T., Alcohol Customs and Rituals, Chelsea House Publishers, New York, 1986.
Bennett, Judith M., Ale, Beer, and Brewsters in England: Women's Work in a Changing World 1300-1600, Oxford University Press, Oxford, 1996.
Bibbesworth, Walter, Le Traité de Walter de Bibbesworth, Annie Owen (translator), Press Universitaires De France, Paris, 1929.
Boorde, Andrewe, A Compendyous Regymentor a Dyetary of helth, 1557.
Boulton, Chris and David Quain, Brewing Yeast and Fermentation, Blackwell Science Ltd, Oxford, 2001.
Burgess, A.H., Hops: Botany, Cultivation, and Utilization, Leonard Hill, London, 1964.
Cornell, Martyn, “A Short History of Hops”, Zythophile: Beer Now and Then, 2009, https://zythophile.wordpress.com/2009/11/20/a-short-history-of-hops/, retrieved 11 February 2015.
Corran, H.S., A History of Brewing, David Charles, London, 1975.
DeBenedetti, Christian, “A Brief History of Sour Beer”, The New Yorker, 26 July 2013.
DeClerck, Jean, A Textbook of Brewing, Siebel Institute of Technology, Chicago, 1994. (1:587.)
Digbie, K., The Closet of the eminently Learned Sir Kenelme Digbie, kt., Opened..., London, 1669.
Dornbucsh, Horst, “Gruitbier: Style Profile”, Brew Your Own, Jan/Feb 2006.
Fourneau, Auguste, L'abbaye Notre-Dame de Saint-Remy à Rochefort. Histoire d'une communauté cistercienne en terre de Famenne, 2nd edition, Abbey of Saint-Remy, 2006.
Fleet, G.H., and G.M. Heard, “Yeasts-Growth during fermentation”, In: Wine Microbiology and Biotechnology, pp.27-54, Hardwood Academic Publishers, Switzerland, 1992.
Fox, The London and Country Brewer, 2nd Ed., Half-Moon and Seven Stars, Westminster Hall, 1736.
Great Britain Privy Council, Acts of the Privy Council of England, Volume II, 1547-1550, John Roch Dasent (editor), Eyre and Spottiswoode, London, 1890.
Green, Joseph R., The Soluble Ferments and Fermentation, University Press, Cambridge, 1901.
Hagen, Karl, “The Economics of Medieval English Brewing”, Polysyllabic, http://www.polysyllabic.com/?q=medieval/brewing, retrieved 16 January 2015.
Hardwick, William, Handbook of Brewing, CRC Press, Florida, 1994.
Hardy, Fred, “Medieval English Brewing”, 28 September 1995, rec.crafts.brewing, retrieved 11 February 2015.
Herz, Julia, “Spontaneous Fermentation: Science, Not Sorcery”, Craft Beer Muses, http://www.craftbeer.com/craft-beer-muses/immaculate-fermentation-science-not-sorcery, retrieved 17 January 2015.
Hornsey, Ian S., A History of Beer and Brewing, Royal Society of Chemistry, London, 2003.
Hudson, William et al, The Records of the City of Norwich, Ulan Press, 2012.
Huxley A, "Discourses: Biological & Geological (volume VIII) : Yeast", Collected Essays, 1871.
Kiefer, David M., “Brewing: A Legacy of Ancient Times”, Today's Chemist at Work, American Chemical Society, December 2001.
Kistemaker, R.E. and V.T. van Vilsteren, Beer! The Story of Holland's Favourite Drink, De Bataafsche Leeuw, Amsterdam, 1994.
Mascall, Leonard, Booke of the art and maner, how to plante and graffe all sorts of trees Arte of planting and graffing, Henrie Denham, London, 1589.
McLean, T., Medieval English Gardens, Viking Press, New York, 1981.
Meade, Ronan, “Yeast Research Project Documentation”, http://mbhp.forgottensea.org/dyrp.html, retrieved 15 January 2015.
Nelson, Max, “Beer: Necessity or Luxury?”, Avista Forum Journal of Medical Science, Technology, and Art, 21:1/2, Haverford College, Pennsylvania, 2011, pp 73-85.
Palmer, John J., How to Brew, 2nd Ed., Defenestrative Publishing Co., California, 2002.
Parker, H.H., The Hop Industry, P.S. King and Son Ltd., London, 1934.
Patterson, Mark and Nancy Hoalst-Pullen, The Geography of Beer: Regions, Environment, and Societies, Springer, New York, 2014.
Placeway, Paul W., “Recreating Medieval English Ales”, 1998, http://www.cs.cmu.edu/~pwp/tofi/medieval_english_ale.html, retrieved 9 February 2015.
Pliny the Elder, Natural History XII, translated by John Bostock in The Natural History: Pliny the Elder, Taylor and Francis, London, 1855.
“Recreating the perfect British pint”, British Brewer, http://www.britishbrewer.com/tag/history/, retrieved 11 February 2015.
Reis, Mike, “How to Identify Yeast Flavors in Beer: Wild Yeast and Bacteria”, Serious Eats, 14 March 2013, http://drinks.seriouseats.com/2013/03/sour-beer-what-is-brett-lacto-pedio-wild-yeast-flavors.html, retrieved 9 February 2015.
Renfrow, Cindy, A Sip Through Time, Vanity Press, 1995.
Saint Peters List, “The Ten Authentic Trappist Monk Beers”, History / Life & Leisure, 20 December 2013, http://www.stpeterslist.com/197/the-7-authentic-trappist-monk-beers/, retrieved 11 February 2015.
Salem, Frederick W., Beer: Its History and Its Economic Value as a National Beverage, F. W. Salem and Co., 1880.
Scot, Reynolde, A Pefite Platforme of a Hoppe Garden, Henrie Denham, London, 1576.
Shea, Andrea, “Brewers Gone Wild: Taming Unpredictable Yeast For Flavorful Beer”, The Salt, 23 January 2015, http://www.npr.org/blogs/thesalt/2015/01/23/379326150/brewers-gone-wild-taming-unpredictable-yeast-for-flavorful-beer, retrieved 5 February 2015.
Shulver, John, “Early Medieval Brewing”, Regia Anglorum, 31 January 2005, http://www.regia.org/research/life/brewing.htm, retrieved 11 January 2015.
Spence, Keith, The Companion Guide to Kent and Sussex, Collins, West Link Park, 1973.
Thausing, Julius E., The Theory and Practice of of the Preparation of Malt and the Fabrication of Beer, H.C. Baird and Company, Philadelphia, 1882.
Unger, Richard W., Beer in the Middle Ages and the Renaissance, University of Pennsylvania Press, Pennsylvania, 2007.
van Vilsteren, V.T., “From Herbs to Hops: Outlines of the Brewing Process in Medieval Europe”, Halve Maen, LXIX:3, The Holland Society, New York, Fall 1996, pp 41-46.
von Bingen, Hildegaard, Physica, c.1158, Priscilla Throop (translator), Healing Arts Press, San Francisco, 1998.
Westerson, Jerry, “Searching for Medieval Ale”, Brew Your Own, April 1998.
Willes, Margaret, The Making of the English Gardener: Plants, Books and Inspiration, 1560-1660, Yale University Press, Connecticut, 2013.