How do we know how much alcohol is in beer? The chemistry of alcohol production was worked out by German chemists Karl Balling, Adolf Brix and Fritz Plato in the 19th century.
Yeast converts simple sugars roughly evenly into ethanol and carbon dioxide (More precisely, 2.0665g sugar yields 1g ethanol, 0.9565g CO2 and 0.11g yeast).
But we never measure sugar or alcohol directly, which would be too involved. Instead the sugar or alcohol content is inferred from the beer’s density. But this causes its own problems.
Density is the ratio of the mass of a substance to its volume. It is not a fixed thing and varies with atmospheric conditions like temperature and pressure. Typically the warmer something is, the greater its volume and the lower its density. As a further complication, the densities of different substances change with changes in temperature at different rates. The density of ethanol is more “elastic” than the density of water. Increasing the temperature from 20˚C to 21˚C decreases the density of water by 0.00021g/ml but decreases the density of ethanol by four times as much (0.00085g/ml). *
In practice this means all brewery density measurements have to be taken at a set temperature, nowadays 20˚C, or brewers must cross-reference actual measurements with correction tables to find a corrected value.
How do changes in a beer’s density over the course of its production reflect its alcohol content? If we know how much sugar is consumed, we can use Balling’s work mentioned above to determine how much alcohol is present. Comparing the density of wort before fermentation with the density of beer after fermentation, we can use the drop in density as an indication of how much sugar was converted into alcohol by yeast. But ethanol itself has a significantly lower density than water so the raw density drop doesn’t actually tell the whole story. It overstates how much sugar has actually been converted. Strictly, to find the real residual extract (or ‘final gravity’) of a beer, it is necessary to remove and replace the alcohol from the sample with pure water and measure the density of what’s left.
In Ireland, the official method for the determination of alcohol is given in part four of Alcohol Products Tax Regulations 2004 (S.I. No. 379/2004).** ABV is determined by distilling off the alcohol from a precisely determined volume of beer at 20˚C and then making the distillate up to the original volume at 20˚C and determining the density of the alcohol/water mixture thus obtained (e.g. using an alcohol hydrometer or simply weighing the sample), and then cross-referencing that density with a book of alcohol-water tables.
UK revenue formula makes more concessions to the technical limitations of microbrewers and uses drop in specific gravity as measured by a calibrated hydrometer to determine ABV. ABV is change in specific gravity multiplied by a factor that depends on the size of the drop. It’s an empirical correlation judged to be close enough for practical purposes and easy for microbreweries to implement. One problem with this method is that it’s useless if the beer needs to be diluted after fermentation. Dilution with water lowers the density but by that very fact increases the gravity drop, leading the simple formula to yield an increased ABV!
All in all, it can be seen that determination of ABV is not a simple matter. To close with one further illustration of this. Molecular interactions make alcohol-water mixtures tricky in another way: 50ml of water and 50ml of alcohol do not add together to give 100ml of mixture but actually only 96.4ml! Paradoxically, in other words, the component percentages of alcohol water mixtures don’t sum to 100. In view of all this, perhaps ABV is not the best basis to tax and regulate alcohol concentration in alcoholic beverages but that’s a topic for another occasion.
*Manual of Weighing Applications, part 1. Density. Sartorius.
Why is wine about twice to three times as alcoholic as beer?
Ultimately the amount of alcohol in a fermented beverage is determined by the starting amount of sugar. In wine-making this is a matter of how much sugar is in the grapes. The grapes are pressed to make juice and the juice is fermented to make wine. Simple. The winemaker doesn’t really have much influence over the sugar content of the original juice. Grapes contain as much as 28% sugar by weight, but more usually around 24%. The grapes themselves contain everything necessary to make wine: a powdery coating of yeast, sugar, and water content. Things stand otherwise with beer.
There is no sugar in barley. Beer is made from starchy cereal grains, so the first step in beer making is mixing ground malted barley with water and converting the starches into sugars with the help of enzymes in the malt. But in this case there is something more like a choice on the part of the brewer how much sugar to start off with. About half of the weight of malt is starch that can be converted into fermentable sugars. So, to a degree, the brewer can determine the sugar concentration by deciding how much water to mix with the ground malt.
But it’s not as simple as it sounds for two reasons. First, the sugary liquid needs to be separated from the malt husks and second the process of dissolving and converting the starch dissolves other stuff as well.
The husks are dry, having been dried by the maltster to arrest germination and prevent the starch reserves being broken down and used to grow new barley plants! When mixed into the mash, the grain can absorb about its own weight in water. The first wort drained out of the mash tun can be very concentrated (a specific gravity of 1.100 or Plato: 23.7˚), about the same as wine, but because so much of the sugar extract remains adhering to the husk and otherwise caught up in the grains, it has to be washed out. Washing out the extract dilutes the overall sugar content. So to keep the sugar concentration very high, a brewer has to forgo a lot of potential sugar, at least half and maybe more (although this can be washed out separately as used as a second low abv beer). So the first reason why brewers don’t choose to make beer as strong as wine is that if they do, it means they either waste money or make a very weak beer as a complementary product. Maybe this consideration is not decisive.
In terms of a mass balance, it might go like this. 1kg of malt contains 800g of soluble extract of which roughly ⅔ is fermentble or 53% of the original mass (530g). To dissolve the extract, 2kg water is mixed with the malt. The malt absorbs half the water so only 1 litre is collected. This wort is very concentrated, about 24˚P, or a specific gravity of 1.100. So it weighs 1.1kg and contains 24% extract by weight, or 264g. But not all this extract is fermentable. It represents 264/800 equals 33% of the total soluble material and contains 50% of the available fermentable sugar.
The dissolved but unfermentable extract is mostly carbohydrates and sugars too complex to be broken down by yeast (dextrines) although significant amounts of protein are also present. Dextrines could comprise as much as 15% of the soluble extract. These are pleasant and contribute mouth feel in beer. However, a beer brewed to be as alcoholic as wine still has this extra body not present in wine and tastes cloying and syrupy.
That’s basically it. Beer can be as strong as wine, but it is wasteful to make it that way and it doesn’t taste nice when it is.
Despite being a brewer now by profession, I still brew beer at home because it’s fun and it helps me get to know different ingredients better. But how much does it actually cost.
First there is the cost of ingredients. I aim to produce 10 litres of beer each time. The amount of malt I use for this varies depending on the sort of beer I’m going for but my last brew used about 2.15kg of malt. My homebrew shop charges €2.21 for this. I use 4g of gypsum at €9/kg, and 2g of calcium chloride at €8/kg to harden my brewing water (5.2c). I use 1g brewtan in the mash and 1g in the boil at €34/kg (6.8c). I use 1g of kettle finings at 5c/g (5c). I use 1pk of yeast at around €3/pk. And I use about 50g of hops at €40/kg (€2). Altogether that comes to €7.38
Now let us calculate the costs of the process. I give my time for free. I also charge nothing for the “quality control” that comes later!
We pay 15.87 cents + VAT at 13.5% = €0.1801245 per kWh for electricity. I will neglect the standing charge because we pay that whether or not I brew beer at home.
We pay 4.61 cents + VAT at 13.5% = €0.0523235 per kWh for gas. likewise neglecting standing charge.
I draw hot water from the tap at 55˚C. The temperature of our incoming water feed is 16˚C at this time of year so our condensing boiler has done the first part of heating for me. I don’t know how efficient my condensing boiler is, but according to wikipedia a typical rating would be 90%.
I used 5.375 litres of water to mash in (2.5:1 liquor to grist ratio). Assuming 1 litre weighs 1kg and that water has a specific heat capacity of 4.2kJ/kgC, then my condensing boiler has to put in (55-16)x 5.375 x 4.2 /90% = 978.25 kJ or 0.2717361kWh work = €0.014
I heat my mash water on the gas stove. According to this link, stove top heating is about 70% efficient. The water is heated from 55˚C to a strike water temperature of 75˚C for mashing in. (5.375kg x 4.2kJ/kgC x 20˚C /0.7% = 645kJ =€0.0094
I boil the jug three times and add it to my mashtun and swish it around to heat it up before adding the hardened brewing water. 1.5 litres x 3, heated from 16˚C to 100˚C in an electric kettle which is 100% efficient is: 4.5kg x 4.2kJ/kgC x 84˚C = 1587.6kJ =0.441kWh = €0.08.
I aim for 15 litres of wort in the kettle, and I assume 1 litre of water will be absorbed by the malt, so I need 15 + 2.15 = 17.15 litres of water altogether and I’ve already heated 5.375 litres so I need to heat another 11.775 from 16˚C first to 55˚C in the condensing boiler and then to 80˚C on the stove. This comes to 3909.3kJ = €0.057.
During my last brew, I boiled the 15litres of wort down to 9 litres in my electric boiler. This was a bit over kill. I was aiming for a post-boil volume of 12 litres. Here I’m trying to find a compromise between giving the hops enough time to isomerise, which needs a minimum of a 30 minute boil, and getting enough evaporation to drive off smelly sulphur vapours. The latent heat of evaporation of steam is 2260kJ/kgC. I’m going to assume my electric brew kettle is 100% efficient too because I keep the elements clean and they are submerged directly in the wort. The 15 litres were collected at a temperature of 70˚C so I first had to heat them up to boiling point. So I used 6kg steam x 2260kJ/kgC + 15kg wort x 4.2kJ/kgC x 30C = 15450kJ = 4.29kWh = €0.77
We don’t pay for water, but Dot doesn’t like me wasting water so I freeze plastic drink bottles full of water and add them to the wort to cool it down. I use about a kg of this. The latent heat of fusion for water is 333.55kJ/kgC so 333.55kJ. (Plus at this time of year, my incoming water temperature is so high (16˚C) that it would take forever to cool the wort down to 18˚C. Heat exchangers work best when the difference in temperature is great. I still do use a heat exchanger to cool my wort, but I don’t try to cool it all the way to pitching temperature this way). I’m not sure how efficient my freezer is. If it was 100% efficient, creating 1kg ice from 1 kg 16˚C tap water would be 1kg x 4.2kJ/kgC x 16˚C + 333.55 = 400.75kJ, or €0.02.
I don’t use any temperature control on my fermentations because I don’t have the set up for that yet. So fermentation is free!
TOTAL COST for 10L of beer = €8.33
How could I save money? Although the electric boil only costs 77c, it’s easily the biggest process cost. Gas is much cheaper than electricity, so I should swap to doing all my heating with gas, even though it is less efficient. I would need a bigger pot for the stove to be able to boil sufficient quantities without it spilling over and making a mess. I could put the hops in a separate pot on the stove and boil them in 2kg of water for an hour and add it back in at the end. This would give me better hop utilisation because tap water has a higher pH than wort. It would also help my precipitate protein in the boil, because hops are a natural antifoam (no hops means more foaming). But I’m not sure the result would be worth the extra trouble, because the kind of hop bitterness produced by boiling hops at a higher pH is supposed to be harsh and astringent. Still, I could perhaps reduce the amount of bittering hops I needed by about half. And I’d save on the costs of boiling because I’d not need to boil the full mass of wort for as long. Maybe I’d only require 55-60% of the heating requirements and be able to meet some of that requirement using a cheaper form of fuel. It would also allow me to shorten the brewday somewhat, because I could overlap the boiling of the hops with the mashing, so when it came to the proper boil later it would be a shorter time.
The raw material costs are the biggest component by far, notably yeast. I can’t avoid this cost, because one of the things I am particularly interested in is trying out lots of different yeast strains. But being able to drop the cost of yeast would reduce costs significantly.
Also, hops are an expensive component. I can’t really avoid this cost either despite the fact that I actually have some hops growing in the back yard, because as before experimenting with different hop varieties is part of the point.
Where Q is the heat required in (kilo)joules M is the mass in kilograms, Cp the specific heat of beer in (kilo)joules/kilogram-kelvin and ΔT is the change in temperature in kelvin. In practice, you can do the temperatures in celsius and the mathematics is the same. And it doesn’t matter if you give the specific heat, Cp, in kilojoules or joules as long as you do the heat Q consistently. The specific heat of beer is 4.05 kilojoules/kilogram kelvin
For example, if you have some cans of beer that you want to cool down in the fridge, you multiply the mass of beer in kilograms by 4.05 and by the temperature drop in celsius and that gives you the amount of heat to be removed by your fridge.
This is the formula you use when determining the power requirement for a cooling system for crash cooling beer in fermenters after the fermentation is finished.
Another formula is used to express the heat created through fermentation, which is an exothermic process. It is ultimately glucose that is consumed in fermentation as maltose is broken down into glucose by the yeast first. The amount of heat produced in the reaction(s) that convert(s) glucose into ethanol and further yeast metabolism has been estimated at 219 kilojoules per mole, which is 1.217kJ/gram (Briggs et al. Brewing Science and Practice, 2004, section 14.2.3). We need to estimate the quantity of glucose to be fermented.
Volume of wort in litres (V)
Specific gravity 20/4 of wort (or the density of wort which is numerically the same).
degrees Plato of wort
Estimated percentage of fermentable extract % —not all the extract is fermentable. Dextrines, proteins, beta-glucans etc are not fermentable by most yeasts. Briggs et al use the value 75% for an average fermentability of wort. Kunze and Narziß estimate closer to two thirds fermentability during primary fermentation.
Fermentable Extract (kg) = Plato/100 x Volume x Specific gravity 20/4 x fermentability%
Q = Fermentable Extract (kg) x 1217 (kJ/kg).
This estimate is actually twice as much as Kunze and Narziß provide.
Narziß states (Abriss der Bierbrauerei,7/e 2005, p.219f) that fermentation produces 570kJ/kg glucose fermented and recommends 780kJ cooling capacity per hectolitre fermenting wort per day, with a peak demand requirement of 2.5 kg extract per hectolitre per day 1465kJ). Cooling surface area should be 2 to 2.5 meters squared per 100 hl. Narziß puts the cooling requirements of ales at 1880kJ/hl day with a peak demand of 4.5kg extract. Cooling fluid shouldn’t ever be cooler than -4˚C to prevent beer freezing on the sides.
I’ve been reading about old-fashioned open fermenters lately and I think they are due a come back in the microbrewery world.
The downsides of open fermenters for big breweries are:-
They need to be cleaned by people. People are expensive. People don’t consistently do a good job of cleaning and fermenters are full of dangerous CO2 gas.
Open fermenters make it hard to collect CO2, which is a wasted resource.
Open fermenters are more subject to infection, because they are harder to clean, and because they are open to the atmosphere, which means there is greater potential for lost product.
Yeast collection (for bottom fermenting yeasts) is harder.
Open fermenters need to be housed in an air-conditioned room, whereas closed fermenters can be sited outside.
Collectively, these downsides mean that there is no way a large brewery would opt for open fermenters now. They simply aren’t efficient enough.
Most, perhaps all, microbreweries seem to have accepted that closed, vertical, cylindroconical fermenters are the way to go. They have the following advantages:-
They take up less floorspace in proportion to their volume. Vertical dimensions mean efficient convection currents inside tank
They can be CIP’d.
They can be used as fermentation and storage/lager tanks.
They make it easy to collect yeast of any kind.
They can be bunged to allow the beer to build up natural carbonation.
The CO2 produced in fermentation can be collected (e.g. it is possible to purge an empty tank with CO2 produced by an active fermentation simply by connecting the headspace of the fermenting tank to the bottom of the receiving tank, perhaps bubbling through sanitiser on the way to ensure no infection carries over this way).
Completely closed system makes it easier to manage multiple different strains of yeast.
Completely closed system helps to satisfy supermarkets’ Global Food Standards requirements.
That said, CCVs are dangerous in their own way. They quickly get very tall, which means you are working at height when you add finings or dry-hops to them (or else you need special equipment to fire the additions in). This can be really dangerous. I once had a nasty accident at the top of a ladder adding dry-hops to a beer at the end of fermentation when the beer had a lot of CO2 in solution. The surface of the beer began to swirl and as if it was about to come to the boil and then a huge wave of CO2 came out of the tank and cascaded over me. I couldn’t breathe. I heard rushing in my ears and began to see stars. I stumbled down the ladder quickly before I passed out, but I easily could have fallen off the ladder. When there’s too much CO2 in solution the beer can geyser out of the fermenter as in this video.
What are the advantages of open fermenters.
High surface area in proportion to their volume leads to an efficient purging of volatiles. No “egg salad” beer.
Easy to see what’s happening to the beer and to monitor it.
Shallowness of fermenters lends to a rapid settling time and promotes beer clarity.
Easy to collect top-fermenting yeast (by skimming)
Easy to dry-hop and fine beers.
Open fermenters can be cooled either by cooling panels in the walls or by cooling pipes submerged in the beer.
It is worth noting that open fermenters used to be how everyone used to do it. Even lager breweries. Beer can be carbonated naturally by moving beer before it has completely fermented out into a closed tank. Open fermenters can be given hoods that will direct the CO2 somewhere for collection. Yeast can be cautiously scraped from the bottom of the FV and washed or made into a slurry with fresh cold water and collected after the beer has been moved.
Open fermentation, however, can only be carried out commercially successfully if the fermentation cellar is adequately air-conditioned. There needs to be regular refreshing of the air because the CO2 produced from fermentation can rapidly become toxic. Wikipedia currently puts the content of co2 in the air at 0.04%. The safe operating maximum is 0.5%, or for brief periods up to 1.0% (Kunze Technology: Brewing and Malting 5/e 2014, p.553). It can easily go above these levels in closed rooms. The air needs to be cool and dry and preferrably filtered. The room can’t have any overhead pipes that might serves as dust traps or places where drips might form. The floor has to be easy to clean and the walls and floor of the room and the sides of the fermenters should be smooth.
There’s a nice video and some photos of open fermenters in use at Edinburgh’s Caldonian Brewery here.
In the previous post, I tried to say why I think the UK beer consumers’ organisation CAMRA is right to stay focussed on cask ale. I more or less said that cask ale is special and distinctive and I want to take this post to try to spell out in more detail what makes it unique.
CAMRA’s definition of real ale is
live unpasteurised beer that is served from the vessel it was finished in without CO2 dispense gas. [link]
This definition talks about both the liquid and the way it is dispensed. As far as I know, it is the only craft-beer-concept that makes specific reference to how the beer is dispensed.
Unlike the American definition of craft beer, CAMRA’s definition does not specify an upper limit on how big craft breweries can be.
Unlike the Italian definition, CAMRA’s definition does not specify that the beer is unfiltered. Real Ale may be filtered and then reseeded with fresh yeast prior to final packaging.
Unlike the German Reinheitsgebot, it does not specify the ingredients that may go into beer or the process aids that might be used to clarify it.
Why focus on dispense? Dispense seems like a secondary, incidental consideration.
To understand cask ale you have to understand about the physical consequences of the particular way cask ale is dispensed.
Because casks are not completely gas tight, the evolving CO2 is slowly released while the beer is in the pub cellar, so cask ale does not attain the degree of carbonation other beer does. (this is one way cask ale differs from bottle-conditioned beers, which are often highly carbonated).
Cask ale needs to be kept at cellar temperature because that is the coolest temperatures the yeast in the beer will stay active at. Cask ales are fermented with yeasts that prefer to work at slightly higher temperatures (18-23˚C… kinda like people).
Cask ale is packaged with a limited amount of fermentable material, and once it’s gone it’s gone, which means it will lose carbonation slowly once it’s opened and go flat (even flatter). This limits the shelf-life. No one likes beer that is completely flat.
As the cask is emptied, air is drawn into the cask, which means the flavours can develop over time. Unless the cask is consumed in reasonable time, however, the air can lead to infections or staling.
Now a sceptic might say, “Well, if all that bad stuff happens, why would you want to keep such a poor and unsatisfactory mode of dispense?”
The simple answer is that those consequences of cask dispense create something that is really quite nice. The gentle carbonation and the slightly warmer serving temperature bring flavours out of the beer that you would otherwise miss. The best examples of cask ale have an incredible complexity and character. It doesn’t suit every beer, which is why I think it deserves to be thought of as a style in its own right.
Cask ale is different because the peculiarities of its dispense give it an social-institutional dimension none of the other kinds of craft beer have. It’s still work in progress when it leaves the brewery. The role of the publican/cellarperson is almost as important as the brewer. One of the things working in breweries has taught me is that the costliness of mistakes increases the further through the production process you go. If you do something wrong on the brew day, you may lose the day and the price of the ingredients. If something happens to the batch after it’s fermented out, you’ve lost the brew day and the ingredients, but you also lost all the time it was in the tank as well. If you put the beer into bottles and then mislabel it so it cannot be sold, you’ve lost everything previous and then the cost of the bottles and the labour of bottling. If you have to recall something in trade, you have all the previous losses, plus the reputational damage, plus the cost of compensating others and so on. Because the cellarperson is the last person in the cask ale production chain their good judgment is important because their mistakes would be correspondingly costly (even if only restricted to a cask-sized portion of a batch and even if the publican has already paid the brewery for the liquid). The reputation of the brewery cannot escape unaffected if the cellarperson does a bad job.
Cask Ale is low-tech, not to say primitive. No refrigeration. No industrial dispense gas. It works with nature and accepts the limitations and boundaries imposed by nature. And it calls for experienced judgment in its manufacture and dispense making it craft beer in the best sense of the word.
[Important Caveat: I have been a CAMRA member for several years, but I have no official position in CAMRA and do not speak with any special authority. The above is just my opinion.]
It seems clear that whereas the definitions of OE ealu, medu, and win are much the same as the definitions of their derivatives, ealu being a malt-based alcohol, medu fermented honey and water, and win fermented grape-juice, OE beor was a drink made from honey and the juice of a fruit other than grapes, as the glosses ofetes wos and æppelwin suggest. (Old English Beor, p. 90).
I recently re-read Christine Fell‘s paper “Old English Beor” (from Leeds Studies in English, n.s. 8 (1975), 76-95) on the topic of the where the modern English word for beer comes from. Fell argues that Beor did not mean beer as we know it at all but was a sweet- tasting, highly intoxicating, drink made from honey and the juice of a fruit other than grapes. Martyn Cornell, following Fell’s work, suggests it’s ‘somewhere between possible and probable – that beór was, in fact, fermented apple juice.’ I don’t think that is true.
Two distinct but related questions.
In my opinion, there are really two distinct but related questions. The first is what was the substance called beor by the anglo-saxons, or what did beor mean? The second is where did the (modern English) word ‘beer’ come from? One scenario is that the substance called beor by the Anglo-Saxons was cider and that the word stopped being used this way after the Norman Conquest (in much the way French words like beef and mutton were borrowed into English). Then, when beer began to be imported into the UK from Holland, ‘beer’ came to be used for hopped ale to distinguish it from unhopped English ale.So there’s a etymological discontinuity between O.E. Beor and Mod. E. beer.
Another scenario is that O.E. beor and Mod. E. beer are etymologically continuous, and the modern English word is a direct descendant of the Old English word, even though the Old English word might have had a very different sense then. For example, in C.S. Lewis’s Studies in Words, he describes how the modern English word sad (meaning unhappy) derives from Old English sæd meaning full. Over time sæd changed its sense, acquiring the meaning heavy, and eventually by metaphorical extensions came to its present meaning. That it is in one sense the same word whose meaning has changed over time is established (as much as these things can be) by a series of quotes fromdifferent periods.
It seems to me that the existence of a body of quotes where the same word (making allowances for minor changes in spelling conventions) can be recognised over the course of hundreds of years is sufficient to show that the Mod. E. word beer comes from the O.E. word beor. The entry for beorin the Bosworth-Toller dictionary of Old English, starting with a quotation from the epic Beowulf poem of the late 5th century, is continued in the entry for bēr in the online Middle english Dictionary which has quotes starting around 1150AD then 1275, 1300, 1330, 1377-99, 1404-5, 1450, 1467, up to 1483.
But beor might have meant something totally different back then. Christine Fell looks at the context of where the word appears and the compound words it features in to build up information about its likely meaning and connotations. The first thing we notice is that Beor doesn’t occur nearly as much as ealu (ale), medu (mead), or win (wine). Also it’s more likely to occur in poetic rather than practical or functional contexts or compounds, which suggests it belongs to a different register (the same goes for medu but even more so). But belonging to a different register doesn’t mean they differ significantly in the sorts of thing they are words for. Horses sweat. Men perspire and women glow, after all.
The strongest evidence that beor meant something other than ealu/ealaþ in Anglo-Saxon times comes from the material gathered in Rev. Cockayne’s Leechdoms Wortcunning and Starcraft of Early England. On page 298 there is given a list of the relative weights of a measure of oil, ale, wine, beor, honey, butter, meal, and beans. Ale and beor have different relative weights so they cannot have been the same drink. The Leechdoms is a medical tract detailing various treatments and preparations for different conditions. Ale and wine are used more often than beor and as Christine Fell observes, when they occur together the instruction is to sweeten the win or ale but not the beor, indicating that the drink is already sweet enough. But was it already sweet enough because the drink was naturally sweet, or was it sweetened as a matter of course during preparation/serving?
Christine Fell notes that in the poetry of Old Norse, which is a relevant related language and which also has four words vin, öl, mjöðr, and bjórr (and mungát, which is apparently strong ale) the verb frequently used of mjöðr, and bjórr is blanda (to blend, mix) whereas öl is simply ‘called for’ (heita). Perhaps beor like bjórr was blended with something to sweeten it at serving. This might explain why the Leechdoms cautions against pregnant women and people suffering certain illnesses drinking it (because whatever it was mixed with might harm the baby).
Old Norse scribes writing in ca. 1200AD apparently glossed Latin mulsum as bjórr. This seems to identify it with mead. On the other hand if bjórr was a mixed drink, this would explain the otherwise puzzling reference to biorblandoðu vini in Elis saga, which Christine Fell discusses. This looks like it means beer-blended wine. But maybe it is wine blended like beer not blended with beer.
O.E. beor was also used as a gloss for Latin mulsum and for Latin Hydromellum (literally honey-water), both of which mean mead. Æppelwīn was also used as a gloss for hydromellum, perhaps because Isidore of Seville said hydromelum was made from water and apples (Etymologies, Book XX).
Maybe that should be the end of the matter: case closed. But I don’t find the evidence of the glosses conclusive because the glossing could be an act of interpretation, rather than of translation. It’s not like a medieval dictionary. The scribe could have been writing down what they thought the author meant, sort of ‘making-it-applicable-to-us,’ rather than what the word meant. At any rate, I don’t think you can say Æppelwīn = hydromellum = beor. Therefore, Æppelwīn = beor.
For all that the evidence from the Leechdoms and the glosses shows, beor could still have been a beer in the sense of an alcoholic drink produced by fermentation of sugars predominantly derived from cereals. Perhaps ealu is your low ABV lusty quaffer and beor is your high-starting-gravity high-finishing-gravity viscous and heavy sipper. Or beor was the hard to get prestige drink, perhaps, because it was kept for a long time before serving and was served with honey and spices. It might have been especially intoxicating not purely because of the alcohol content but because the spices might have been intoxicating.
All this is speculation, of course. But the speculation only has to show how textual evidence offered by Christine Fell can be made consistent with beor being something we would call beer in the general sense now (i.e. a cereal-based drink). The etymological continuity stretching from OE beor, through ME bēr, to ModE beer is the main point of the case.
Against the Cider Hypothesis
It seems to me that identifying beor with cider faces the following problems
Cider is not especially alcoholic. It has a usual starting specific gravity of 1.060-1.070 depending on the apples, which is more than ale usually is, but not very high and less than wine. And malt-based drinks, barley wines, have higher starting specific gravities. (Cider would have to be chaptalised with honey to get to something as potent as wine).
Cider is not especially sweet (unless it is blended with fresh juice or honey before serving). But if we’re talking about blending before serving, we might as well go with strong stock ale as a candidate for beor.
If the word beor meant something like cider/fruit wine/etc, there would be a etymological connection to fruit, but as far as I know there isn’t. (apparently there is a Norman French dialect word bére meaning cider, which could have been borrowed from the Old Norse word bior/bjórr if it meant cider, but there isn’t a demonstrated continuity there like there is in English, and it raises the question why, if the Norse settlers of France used an Old Norse word for cider when they lived in France (bjorr) AND contemporaneous Englishmen used a cognate word (beor) for cider, the Englishmen switched to a completely different word after the conquest.
There is an obvious word for cider in Old English already, namely win and more specifically æppelwin.
If beor wasn’t cider and it wasn’t beer, it might be significant that OE beo meant bee, or perhaps it was fermented birch sap since we have OE beorc meaning birch.
The German word for beer
Da das Brauen von Bier (wie auch der Hopfenanbau) zuerst (seit 6./7. Jh.) nur in Klöstern betrieben wird, ist Herleitung von spätlat. biber ‘Trank’, zu lat. bibere ‘trinken’, zu erwägen. [link] (As brewing beer, like growing hops, was first carried out only in monasteries (from the 6th and 7th centuries) the derivation from late latin biber drink, from Latin bibere to drink, should be considered).
I find it puzzling that the etymology of the German word das Bier is supposed to derive from vulgar Latin biber to drink. Grapes don’t flourish in northern Europe and the peoples of northern Europe would have been drinking beer (that is alcoholic drinks fermented from sugars derived from cereals) since forever. Why would they have borrowed the word from Latin? The pagan German tribes were pre-literate so of course it’s only attested from the 6th and 7th centrury in monasteries.
According to Christine Fell, something clearly cognate with beor is present in all the West Germanic languages, but not Gothic. The part in the bible where it says John the Baptist drinks neither wine nor strong drink (Luke 1:15) Gothic has leiþu, which online dictionaries of Gothic give as strong drink (or, interestingly, cider or fruit-wine). But given the very restricted corpus of Gothic, perhaps that translation is arrived at purely on the basis that translates Greek σικερα.
While there is no attested word for beer, Gothic did seem to have a word beist, used to translate Greek ζυμε, that meant ‘sourdough’ or ‘leaven‘ i.e. a yeast starter, that is potentially connected with beor on semantic grounds given that r/s/z frequently frequently displace each other in languages—a sound change known as rhotacism and known to be missing from Gothic but present in the other Germanic languages .
My argument in summary:
There is an etymological continuity between Mod. E. beer and O.E. beor.
There is no demonstrated etymological continuity between O.E. beor and any vocabularly connected with apples.
There is pretty good evidence that beor and ealað were different drinks, but if beor was something like old stock ale blended and sweetened at the point of serving, it would fit the evidence too.