Alcohol Measurement in the Brewery

Ken writes:

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.

Laboratory distillation apparatus.

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.

<>  page 5 (accessed 12 August 2017).


**Alcohol Products Tax Regulations 2004 <> accessed 19-08-2017.


The relative alcoholic strength of beer and wine

Ken writes:

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.


barley starting to sprout
barley starting to sprout

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.

How much does my home brew actually cost to make?

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.


Cooling requirements in the Brewery

Ken writes:


The general formula for cooling requirements is:

Q = M x Cp x ΔT

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.

Kunze’s numbers agree with Narziß.


ken writes:

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 from different 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 beor in 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

  1. 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).
  2. 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.
  3. 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.
  4. There is an obvious word for cider in Old English already, namely win and more specifically æppelwin.


Random Curveball

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.

The Beer Belt (Brauwelt International, 2018ii, p.82
Distribution of predominant alcohol varieties in Europe (from N & C McGregor, Brauwelt International 2018/ii, p.82)

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.



Hazed and confused

Ken writes:


I started writing this post a year ago when I was about six months into a new job. We had  dreadful problems filtering beer for sale and very slow lauter times. I didn’t get round to finishing the post then, but we turned the problems around so I thought it might be helpful to anyone in a similar predicament to hear what we did.

The description of the problem.

The problem was basically two fold: It took forever to filter beer to remove chill haze, and it took forever to lauter the wort. Chill haze is a mild form of turbidity that forms when different compounds are precipitated out of the beer by cold temperatures and adhere together forming tiny particles. We had to filter one or two beers we brewed on contract and our own lager. A three thousand litre batch would take all day to filter despite the fact that the filter was rated for 3000 litres per hour. Some of the time was just setting the filter up and cleaning it down at the beginning and end of the work, but the time in the middle was dire. “lautering” is the process of separating the husks and other undissolved matter from the sweet wort after mashing. When it came to lautering, if we got the wort out in 3 to 3.5 hours we were slapping each other on the back and giving each other high fives. We were staggering our  starts because it took about 10.5 hours for a single brew. Everyone was exhausted.


Kettle and lauter tun


Lauter times

They say problems in the tank farm usually have their origin in problems in the brewhouse so I’ll talk about that first.

Although we had a really top notch 30hl Kaspar-Schulz brewhouse, we were running it on a manual basis because the automation program hadn’t been installed. The brewery was purchased second hand and the original automation program couldn’t be installed when the brewery was put it in. The local electricians weren’t up to the job and many of the wires connecting the sensors to the plc were connected wrong. The plant was capable of excellent lauter performance, but we weren’t using it correctly. We subsequently got our lauter run off time down to less than 90 minutes, so that shows what it was capable of.

Inside the lauter tun


We did a number of things to try to improve lauter performance. We opened up the mill settings to produce a coarser crush in the hope that this would provide a better filter bed. We tightened the mill settings to produce a finer crush (because opening the mill hadn’t helped—maybe unmodified gelatinised starch adhering to the husk was settling at the bottom of the tun and forming a layer of impermeable gunk).

We seemed to run the first worts off too quickly so we started slowing that right down. We would run off only with gravity and then throttle the flow in addition to that. But still it didn’t really help. We would eventually have to underlet and smash up the grainbed with the rakes and then recirculate for ages, which would compact the bed again, or let cloudy wort through to the kettle.

The bed was always pretty dense and settled like a slab on the base of the lauter tun. It seemed like every mash was a stuck mash.

The beginning of the solution was changing how we operated the mashtun/kettle. The kettle had paddles in the bottom to prevent the mash burning on to the base of the kettle during heating up between the various rests. We used the paddles at full speed when we mashed in to ensure there were no dough balls and to obtain and even heat throughout and full-speed while we were heating, but we continued to paddle at half-speed during the rests/stands. When we stopped doing this, the mash remained more buoyant when we transferred it to the lauter tun. It still settled on the base of the tun, but it had a certain buoyancy that had been missing.

The next change was in raking behaviour. We had played around loads with the rakes adjusting the height at which they operate and their speed but couldn’t settle on the right regime. Eventually we hit on it. We completely ignored the height adjustment and left the rakes at the bottom of the tun. The reason for this was that plenty of lauter tuns are actually designed with rakes set at a fixed height, so the height at which they operate couldn’t be very significant. The speed adjustment was important. We set the speed to one revolution every two minutes. This wasn’t enough by itself. The break-through was stopping the run off during raking. Running off during raking must pull fine particles lower and lower into the bed. Raking by itself served to loosen the bed without sending the fine particles to the base of the tun.

Once we discovered this, and obviously it would have been built into the original automation programme, we could speed up running off the first worts. We would run the first worts off in 25 minutes or so, add some sparge water and then rake to loosen the bed again, and begin running off after the raking had restored the pressure difference across the bed, as measured by two sightglass tubes, to near equality. I’m convinced here that the critical development was not running off while we were raking.

It all seems so simple now, but it took us a long time to identify the decisive measures while we were struggling because there were so many possible things that could have played a part. Different malt bills were certainly relevant, with the lighter beers being easier to manage than the darker ones. There seemed to be recipes that were particularly bad and we experimented with using malts from different manufacturers and even changing the recipe completely (leaving only the final colour the same). It took such a long time to get feedback regarding any change. Raking in the wrong way can do lots of damage to the lauter performance, but you don’t discover this until the damage is already done.

Chill Haze filtration

There can be a number of reasons why you may have trouble filtering beer. We had a filter skid set up with a 3 micron, 1 micron and 0.5micron sequence of ever tighter filter cartridges to yield a virtually sterile product. The tighter cartridges could be bypassed if we only wanted to filter out yeast. The 3.0 micron was only nominally rated, meaning that some particles smaller than 3.0microns could pass the filter (just not very many). The 1.0 micron and 0.5 micron cartridges were absolute ratings (nothing smaller than the rated size should be able to pass through).

We occasionally had problems with the 3.0 micron filter but generally did not. If we fined the beer and moved it into a dish-bottomed conditioning tank before filtering, then we had no problems. Filtering straight out of a CCV caused problems when a large plug of yeast would dislodge itself and get sucked into the filter housing and then block the filter cartridge immediately.

The 1.0 filter was there to protect the 0.5 micron filter. It did its job very well and we hardly ever had to change the 0.5 micron cartridges. The 1.0 micron filter always blocked. We wondered if it was yeast passing the 3.0 micron filter so we put 2.0 micron cartridges in before the 1.0 micron to see if that would make a difference, but it didn’t help. So the haze creating particles were smaller than 2 microns but bigger than 1.

They say problems in the tank farm are almost always traceable back to problems in the brewhouse and it sort of was that way for us too. We noticed that certain recipes never gave us any trouble filtering so we looked what they had in common and they all involved a low-mashing in temperature and a protein rest. As a result of this, we introduced a number of steps to reduce the amount of protein in the finished beer. We mashed in at 45˚C (to allow some beta-glucanase activity) and then heated through to the saccharification temperature at 62˚C, and then a starch rest at 72˚C, and then mash out temperature of 78˚C. This didn’t involve a protein rest as such, but gave the proteases scope to work. (We were mindful that we did not want to degrade the proteins responsible for beer foam too much as the boss had a very strong preference for good foam on beer). We also brought the mash pH more under control. The best lauter performance seemed to be at around pH 5.4. The feeling was that if the lautering goes easily that will be better for filtering as well because the wort will already be cleaner. We boiled for 15 minutes prior to adding hops to get lots of foaming in the kettle. We slightly increased the amount of kettle finings we used and we changed the way we transferred the kettle contents to the whirlpool to avoid breaking up large protein flocs. Finally, we started using a colloidal silica solution in the conditioning tank when the beer was cold. of these measures, I believe the protein rest/low mash in temperature made the biggest difference.

There were a couple of cul de sacs. Adding Brewtan B, a solution of tannic acid, to the mash or to the boil did not seem to help much. It could be however that it had a positive effect but for some unrelated reason this was cancelled out by something else. You have to remember that we were still producing beer at a very hectic pace throughout this time and there was a gap between brewdays and filtering days and so day-to-day demands on our attention meant it wasn’t always easy to relate what we were seeing in one part of the brewery to what had happened a couple of weeks ago somewhere else. We had loads of problems with our tank farm cooling so we always seemed to be lurching from one problem to another. That got sorted in the end. Buíochas le Dia.


Happy Ending

It’s incredibly satisfying when you feel you have solved a problem in the brewery. It’s such a complex operation and so interconnected that you can never really take an off-the-shelf solution from what you’ve read or found elsewhere. I was lucky to have a number of really quite eminent brewing scientist friends who could be called on to help me understand the problems but no one was able to just walk in and diagnose and treat the problem straight-away. You have to know the brewery equipment fairly intimately. Even purely physical things like vessel dimensions and materials, agitator speeds, pump types, pipework, heating capacity can make a difference, to say nothing of the chemistry of the different processes. But it all serves to make you feel even better when you do finally get it right.



The Wife’s Lament

As part of a module I’m teaching this term I’m getting the students to write creative pieces prompted by Old English texts. I thought I’d have a try at doing one myself, so here’s something based (loosely) on the Old English poem ‘The Wife’s Lament’. The length limit for the exercise was 1500 words and I’ve come in just under.


Today she’s sad. I find her easier to cope with when she’s angry, to be honest. Then I rise up on the boil of her rage, up the dark steps like a messenger from the netherworld.

“Why did you pick this horrible basement flat?” I ask her.

“He told me to piss off back to Grove Road,” she says, “So I did. It’s all I can afford now anyway.” She’s sad today.

She misses him, after all these years, and I suppose I have to respect that, though I find it hard to understand. He was such an utter prick to her.

“We were soul mates,” she tells me. “Everybody saw the talent, the outrageousness, the way he could dominate a room, but I saw the sadness in him. The need. He was just a little boy really, always needing a woman to care for him.”

Of course this need for a woman’s care extended to sleeping with someone else the night she gave birth to his baby. But one has to try to understand the human psyche in all its rich complexity.

Continue reading “The Wife’s Lament”


Dot writes:

fiction isn’t happening for me and hasn’t been for a while. It’s not that I don’t have ideas, just that none of them go anywhere. They are sedentary ideas, reluctant to venture into the January wet, slumped in front of their computers. Is it worth getting any of these moving?

Quiche Lorraine

Quiche Lorraine is a heroine who works as a canteen lady at a tech firm. Once, helping to unload the Tescos delivery at the back of the office block, she spotted a nefarious character seeking to enter without a lanyard. Thinking quickly, she threw a quiche in his face and he gave up the attempt. Thus her name. Few people know how she got it but the ones who do recognise it’s a badge of honour.


The problem with Sean was that he had no real interest in anything anybody else said or did. He was very generous, very kind – he’d buy you dinner, or a jumper you liked, or tickets to a film he’d just seen and wanted to tell you about. He was popular with small children because he knew a few magic tricks and was always delighted to show them off. He liked to tell people things he knew, such as the way Teflon pans are made or how events were misrepresented in the currently popular TV history drama. However, if you knew more about that particular historical period than he did he was never going to find out. He would never stop talking for long enough for you to mention it.

So Louisa thought, sourly. The shine had long worn off him as far as she was concerned. Or, rather, she’d realised he was the sort of bright light that only made everything else seem darker – a localised dazzle that didn’t illuminate. And she herself was especially cast into shade, practically invisible, in fact – Sean’s sister and, thanks to personal setbacks, currently, reluctantly, his housemate – appearing briefly on the edge of his sociable evenings to boil a kettle and disappear again. But there are things you can do in the dark.


The girl under the lamp-post smiled happily. She knew she had done well. Duncan had only managed to get a bollard. Kelly was pretending a wheelie-bin was an achievement but, really, it was a flimsy thing and not even fixed to the ground. Look at her tying herself on with pathetic thoroughness, as though you could solve everything with a sufficiently complicated knot. Sometimes it didn’t matter how hard you worked or how clever you were; it was just about where you were standing. The girl under the lamp-post pushed against the belt that strapped her to it, to check it would hold firm.


I Fall Apart

Here are two versions of a song.

This is the one I heard first. It’s sweet and melodic and sad. It immediately became a song I needed to hear many times.

As it happens, it’s a cover, and here is the original. On first listening I liked it far less.

Probably all people who properly keep up with current music have heard the Post Malone version and not necessarily the Flor version, but I tend to come at everything sideways – in this case from letting Spotify play on after the last Haim album, which led me to Flor’s single ‘Guarded’, and some time later to investigating them further. Their recent album is a feast of irresistibly tuneful indie pop and I thoroughly recommend it. Also the singer, Zach Grace, is as cute as a bag of kittens.

But back to Post Malone. The original version of the song definitely grew on me. I post it here partly just to share the song in both renditions, but partly because it’s a case study in how trying to think about things can change my enjoyment or aesthetic experience of them. When I first heard Post Malone I thought “oh, the vocal is a bit forced, when Zach Grace has such a sweet, expressive voice; and the tempo is slower and it seems draggy; and where’s that great bass line I was enjoying; and I don’t like the hip-hop instrumentation as much as those clear and pearly guitar parts” (I was going, of course, from the cover to the original). However, the more agonised and rough delivery of the original version, and that tough guy aesthetic in the general musical style, makes sense with the lyric. “Oh, I fall apart, down to my core” – but he’s trying to self-medicate after his break-up – “harder than the liquor I pour” – and he’s resorting to misogyny in a crap, macho way that just confirms what a mess he is – “devil in the form of a whore”. When Zach Grace sings that line it sounds a bit rougher than the rest but it’s hard to believe he might mean it. When Post Malone sings it you see the ugliness in sadness, how falling apart means feeling and behaving like shit.

That all sounds very intellectually pleasing, doesn’t it? I should prefer the Post Malone version now, as being more insightful or authentic or something. Indeed, thinking through the song’s themes did go hand in hand with acclimatizing to Post Malone’s sound-world. But Flor’s sound is so lovely; and really I’d rather listen to them.

A Walk in the Dark


It was past 6 o’clock on Halloween and already dark as she crossed the road into the Yew Grove estate, the little duffle-coated figure trailing behind her. Oh, how tired she was, how she longed to get home and shut out all the posturings and jargon of her day, but he hadn’t wanted to leave his childminder – he’d refused to fetch his things, wanted to stay in the warm watching tv, and she’d got angry and said there’d be no trick or treating, since he couldn’t do what he was told. And certainly the idea of tramping from house to house smiling politely while hissing at him to say thankyou made her want to scream. But it was mean of her, she knew. She’d tell him he could go after all, just as soon as it was decent to relent. Meanwhile he was dawdling. He was in a sulk.

The houses in this estate were large and blank for the most part: neat blinds, trimmed borders, prosperous cars on brick-paved drives. There weren’t many children here, but a few people had decorated for Halloween, and they hadn’t settled for home-made cutouts or plastic skeletons from Centra. One house had a row of ragged scarecrows in the garden and a single pumpkin carved into a leering face; another had a giant black spider on the wall. “How clever,” she said to herself, but her pace quickened. “Hurry up!” she called to her son.

As she rounded the corner it turned quieter and far darker. Two of the streetlights weren’t working; instead of their yellow glow there was an intermittent white flicker which she realised after a moment must come from LED projectors. On the side of the nearest house a procession of stooped, bony shapes endlessly crept along the wall. Further on wispy ghosts scattered into the eaves. Behind, now the noise of the main road had receded, she could hear the stubborn little footsteps. Suddenly, a great shadow swept across the pavement, so dark she couldn’t help but jump and cry out – what was that? It looked like a clawed, grasping hand, but it missed her, thank god – and of course it must just be another projection, but what a horrible one! She scuttled a few yards more and then stopped and waited. “Hurry up! Run and hold my hand!” She heard him stumble, and looked back, but for a moment she couldn’t see him at all, and the dark lay over the pavement. Then there he was, walking on at the same pace as before. Well, be like that! If he wasn’t scared, he was tougher than she was. She turned and resumed walking.

Round another corner, and they were out of the Yew Tree estate and into the brighter and smaller streets of their own neighbourhood. Soon she’d be able to turn on the television, put on a kettle for pasta, make tea. She hurried to her front door, opened it and flicked on the lights. The small figure finally caught up to her; she let him in and firmly closed the door. And then gazed in horror at the blank white eyes of the creature that was no longer her son.