A new whisky distillery has opened near to me, so I got in touch to see if they wanted anyone to help making their wash. The owner got back to me the next day to ask if I could help with issues with stuck mashes and slow fermentations.
What might not be obvious to anyone new to the field is that the precursor to whisky spirit is something very akin to beer, but without any hops. I always offer the first hour of consulting time free so I can decide if I can add value for the customer and they can get confidence in the knowledge which I offer. We were soon having a fruitful conversation and the reason for their slow / stuck fermentations became obvious after running a forced fermentation test – they had the wrong mix of sugars in their wort (or wash as it’s called in this industry). Could I help to resolve this? Could I optimise their yield to sugar in the wash and could I advise on best practice CIP methods? Yes, yes, yes!
The benefit of employing someone like me is that my Ph.D background allows me to get up to speed in a new topic in hours, not weeks. Understanding the subtle but important differences between wort and wash production made for fascinating reading. In beer production we choose the mash temperature to control the sweetness and body of the final beer, with whisky one is looking to maximise fermentable sugar extraction. To achieve this the grist is mashed at low temperature, almost all the strong worts are run off and then it is subject to a kind of pseudo step mash by sparging at 75 C to activate the α-amylase to convert areas of the starch which are sterically inaccessible to the β-amylase. But since non-fermentable sugars are of little value to the whisky maker, the wort is not boiled but (cooled and) transferred directly from the mash tun to the FV. Here speed of operation is key because the aim is to transfer active enzymes, including limit-dextrinase, into the FV. As the fermentation progresses these enzymes work on the complex sugars to form maltose which can then be converted to alcohol. Thus efficient operating practices will boost the yield to alcohol.
By observation it was clear that the HX (heat exchanger) which had been installed was far too small which was increasing processing times.
A new HX is now on order, but in the mean time it was important to get production running. Employing a trick to make Brut IPA I advised on an exogenous enzyme we could add to the FV to allow the fermentations to run to completion whilst the new HX is awaited. Roll on two weeks and all fermentations are now reaching their desired terminal gravity and I have given hands on help and coaching which has boosted the sugar extraction yield from 67 to 93% and I aim to increase this still further.
Now my role has moved on to training the guys who are going to be running the brewing side of the process, write some SOP’s (best practice training is always based on an SOP) and help embed consistency of operation and thus yield and flavour profile. It is really satisfying to use my process support skills from my time in the chemical industry in parallel with my technical understanding of the biochemistry of brewing to help yield good consistent spirit in good yield. I must confess to be rather enjoying myself.
In November my five months locum / consulting brewing contract with buxtonbrewery will come to a close. What a great group of people. If you are looking for a brewer to help with the demand running up to Christmas or you need someone to cover whilst you recruit and you brew in the NW then drop me a line. If you want to know what you’ll be getting, read the testimonial that Geoff the MD from Buxton presented me this week to aid my transition into future roles
We are living in a challenging time for the small scale brewer. Raw material and energy costs are at an all time high, yet our customers has less disposable income. To maintain your margin without sacrificing quality one, excellent method is to max out the capacity of your brewery. This article is aimed at small brewers, not those with vessels to hold their last runnings to use as the start of the next sparge and the like.
Which vessel is going to limit you?
This is the first question you need to ask – which of your vessels is going to limit your output? Assuming you brewery equipment was bought at the same time, it is unlikely that your mash tun will be your limiting factor. This is likely to have been designed to brew ABV’s higher than your core range beers. So you need to know the volume and thus working capacity of your copper and your fermenters.
It is easy to estimate the volume of these vessels. Most coppers are cylindrical and thus the total volume is easily calculated.
Volume of a Cylinder = Π . r2 . h
The volume of flat bottomed fermenters can be calculated the same way, but if you are lucky enough to have cylindroconical fermenters you need also to calculate the volume of the cone at the base and add this to the volume of the cylindrical section.
Volume of a conical section = Π . r2 . ⅓H
But of course there is a difference between the total volume and the ‘working’ or useable volume. For a copper this is 80% of the total volume. For a fermenter it will be in the range 80-90% depending on variety of factors.
How to maximise the capacity of your copper
There are two options here. If you don’t want to alter your recipe then to maximise the volume that your copper can safely boil you can reduce the foaming that occurs at the start of the boil. As the proteins from the malt denature and drop out of solution they act as nucleation points for the bubbles of the boil and other proteins aid foam stability. This can lead to a deep head of foam during the first 10 minutes of the boil. There are commercial antifoaming agents which can be added at this stage of the boil, but you may not know that the natural product versions of these are actually a hop extract. So if you add around 5% of your hop bill just before the start of the boil (i.e. First Wort Hops) these will reduce foaming without you adding cost or anything artificial into you beer.
Another option would be to consider taking a small step towards high gravity brewing. You can aim for a pre-boil gravity 10-20% higher than your designed post boil gravity, knowing that you can liquor back at the end of the boil either directly post boil, or during the transfer.
How to maximise the capacity of your fermenter
Here again, foam management is key to maximising your capacity. Medium and larger scale breweries would normally fill their fermenters from the bottom to minimise foam formation. As well as increasing capacity it also aids head stability in the final beer. Think of the foam capacity of beer being a fixed value over the whole life of the beer, from manufacture to the customers glass – the more foam you form in the process, the less potential for foam (head) there is in the final beer. In bottom fill operations the wort is oxygenated in-line on the way to the fermenter. However in micro breweries oxygenation is often achieved by top filling the fermenter, allowing the splashing of the work to entrain oxygen and thus avoid the need to buy bottled oxygen.
If you top fill your fermenters to oxygenate the wort the volume of foam can be considerable and limit the capacity of the fermenter. Here an antifoam agent such as Murphys FD20PK or AB Vickers Foamsol can be added during the first 10% of the transfer to dramatically reduce the foam and thus increase your fermenter capacity. I was recently able to increase the fermented volume at a brew-pub client by 7% using this approach.
None of the concepts I have highlighted above require the purchase of any additional equipment. It is not uncommon for a brewery to increase it’s capacity by buying double sized fermenters and filling with two batches of wort each day, but this is likely to mean employing extra staff or paying overtime – so whilst it will increase your capacity, the impact on your margin will be minimal in comparison to the simple optimisation methods I’ve detailed above.
The best approach
When you have decided which process stage you want to focus upon, the best approach is to make a number of step wise changes towards what you have estimated as your maximal capacity. But remember that each increase will need to be in increments of cask volume (i.e. 42 litres for an extra Firkin or 21 litres for a Pin). Gaining an extra 3/4 of a cask does you no good at all!
If you would like help maximising the batch size of your microbrewery, then please give me a call. Similarly, if you would like someone to brew on your kit to cover times of peak output or to cover holidays (without having to employ an additional person full time) then this is another service I am pleased to offer.
When I work as a locum brewer I often get asked “whilst you are here can you also look at…” and have a technical conundrum placed in front of me. I love questions such as these, the following is just such an example.
A client was short of staff for three months and they called me in to cover part of their brewing schedule. It was somewhere I has worked before so the packaging team quizzed me about why they were hearing complaints from customers about higher than normal ullage in the casks of late. I looked at some of their routine finings tests and it was clear they were suffering from fluffy bottoms – not something anyone wants to hear!
So we held back a batch of finished beer for a few hours before any auxiliary finings were added and was able to find the optimal levels of auxiliary and isinglass finings by some simple test work.
The issue turned out to be the level of isinglass that was being charged, the auxiliary level having been proved as optimal via my test work. I then checked out this new finings level on two other beers to confirm and was delighted to see the beer drop bright in < 30 min and give a good dense body of flocs at the bottom of the sample glass. No more fluffy bottoms!
A simple update to their packaging procedure and now a few weeks down the line the customers of my client are happy once again and thus so are they. Such is the benefit of a well trained outside eye looking at your process.
Well deserved recognition for John at the Bird Inth Hand, Darwen
Sadly John nipped out before I could get a picture with him and his CAMRA award for the best Craft Beer Bar in Blackburn and Darwen. I’m delighted for him and proud to say that all of his house beers (4 so far) have been designed and co-brewed by myself on his brew kit installed in the cellar of the bar. My trousers show evidence of a busy brew day making the next batch of the popular Step 1, a NZ hopped pale ale.
I still remember the advice given to me by my first head brewer. “The two most important aspects of brewing” he said, “are cleanliness and temperature control.”
There are three classes of soiling you need to deal with in a brewery:
Organic soiling– that could be burnt on carbohydrates / proteins on the hot side and yeast residues in your fermenter
Inorganic soiling – this would be mostly scale (calcium / magnesium oxide) or calcium oxalate.
Biofilms – these tend to form in places where liquor can lie and which don’t see turbulent flow. Under the plates in the mash tun and in wort transfer lines for example.
Organic soiling
The most frequent / routine soiling you’ll be dealing with is organic soiling in the copper and your fermenters. You want to free this off of the vessel walls and then ensure it remains suspended until you can flush it out. The best cleaning agent for organic soils is specially formulated caustic (NaOH) solution. Brewery caustic formulations come with surface active agents in them to improve wetting, sequest metal ions and keen non water soluble soils suspended.
Your CIP caustic solution should be 1-3% NaOH (normally the concentrate is 30% NaOH). Take care with the concentrate and follow your local risk assessment. Googles and gloves are required and always add caustic to water, not water to caustic to avoid it overheating and spitting.
If you are a micro brewery you will not use huge volumes of caustic and it’s worth being aware that you can usually buy something suitable from your local agricultural merchants as it is also used to clean dairy milk tanks. Take care though as dairies tend to prefer formulations that also contain hypochlorite. Evans Vanodine CIP liquid would be a good choice because it contains no chlorine based chemicals.
Different places where I have worked have had different protocols for the cleaning, but be aware that caustic cleaning is most effective at 50-80 C, needs to be recirculated for 15-20 min and should impact on your surfaces at > 1 m/s to guarantee turbulent flow. Why is there an upper limit you may wonder? That is to avoid baking your solids onto the heated surfaces. Here it’s worth mentioning the Sinner diagram:
You need all these factors to clean equipment, and if you reduce one (say chemical strength) you will need to increase one or more of the others (time, temperature or mechanical action). Once your vessel is free of soil you need to flush the caustic out as you definitely don’t want caustic in your beer. Simple phenolphthalein test papers work well to check the flush water.
With the base of your mash tun (below the plates) it is likely that you’ll not be able to use a spray ball system so you are probably looking at more mechanical action. Jumping into the vessel with a bucket and scourer or using a pressure washer! However this will probably only be necessary 2-4 times a year. This is a vessel entry, so again follow your local risk assessment. Actions should include, locking off any mechanical, chemical or heat inputs that you have and ventilating well.
Often a cold caustic cycle is all that is needed on the fermenter.
Cleaning fermenters – a cautionary tale
After you have transferred the beer from your fermenter there will be a high level of carbon dioxide with it. If you don’t already know, be aware that carbon dioxide reacts with caustic:
CO2(g)+ 2 NaOH(aq) → Na2CO3(aq) + H2O(l)
All of your CO2 gas will become a dissolved solid, result – a big drop in pressure. It is readily possible to collapse an FV because of the vacuum formed. The safe approach to manage this issue will depend on the size of the fermenter. Massive lager FV’s would need an air purge and CO2 monitoring. Smaller vessels can be managed by three x 10 second water sprays and leaving an inlet open during the initial caustic circulation. This worked fine on 5000 L FV’s with a 1 ½” being left open (and a short hose running to the drain). I have seen people leave the manways cracked open but this is dangerous in its own right as you’ll get hot caustic splashing into the work space – no thank you!
Inorganic soiling
In a small brewery you are most likely to see this in your hot liquor tank or in your casks. Here the aim is to solubilise the Ca / Mg salts with a suitable acid. The preferred option being phosphoric acid or a phosphoric / nitric mixture (NiPac B). This should be used at 1-4% and cold or warm, never above 50 C or it will fume. Again you’ll need a good water flush (see below) afterwards and this time litmus paper to check.
Biofilms
A less frequent task. If these are to be removed with CIP you would use your normal caustic solution (1-3%) but add to it some hydrogen peroxide (0.1-0.2%). However these often tend to build up in pipes where the flow rate is slow – such as the drain lines from your mash / lauter tun. Here the answer is mechanical effort! Sadly Murphy’s don’t sell elbow grease… I’ve had great success with a technique I used in the chemical industry called pigging. This is where an abrasive coated foam ‘pig’ is pushed down a line with air or liquid pressure. In the brew house a lower tech solution is required. Tie a foam scouring pad to a rope and pull through your lines until visual inspection shows them to be clean. The beauty, if there is one, with biofilm is that you can easily see it.
Sanitisation
Here there are a number of options, but a really good one is dilute peracetic acid. If used at 100-200 ppm it is not only an effective bactericide but will not need to be rinsed out of the vessel, simply drained. Another tip I learned is that most people can smell a dilute peracetic acid solution when it is above 75 ppm. So if you cannot smell it, either you have COVID or your solution is now too weak. Peracetic acid is another chemical you can buy readily from your local agricultural agent but again is something to be treated with respect as a concentrate and in accordance with your local risk assessment.
Flushing
Flush before you wash – that way the bulk of the soiling will be washed out and the potency of your cleaning chemicals will be preserved for multiple cycles.
Flush after you wash – Here you can work smart and save both time and water. Three ten second flushes will be a lot more effective than one 1-2 minute continuous spray down. The reason is all down to dilution (diluting by 90% three times (99.9%) is much better than diluting by 98% once). The pooling of liquor at the bottom of the vessel.
Need more advice?
If you buy your cleaning chemicals from a large supplier they are normally very happy to come and answer any of your questions. If you are a micro-brewery and this is not an option for you then contact me and I can help. Having worked in the chemical industry before I started brewing means I have a sound background in chemical safety and vessel cleaning methods.
Would you like to take your home brewing to the next level?
Would you like 1:1 coaching from a professional brewer?
Would you like to have a professionally designed beer recipe, complete with water chemistry for your local water of a style of your choosing?
Earlier in the year a former colleague from my previous career (Chemical Industry) approached me and asked if I could shadow him on a brew day to help improve his understanding and technique. He had not been wholly satisfied with the beer he had made to that point and wanted to take his brewing to the next level.
I suggested the following, that we spend half a day covering the essentials of brewing science and looking over his brewing set up, then the next day he could brew with advice and input from myself on the best practice methods to use. For the brew day I had written him a recipe to clone his favourite commercial beer.
We both really enjoyed the two days. He said afterwards:
I wanted to improve my skills as a home-brew hobbyist and found so much conflicting and sometimes confusing information online that I didn’t know which way to turn to improve the quality of my beer which I felt had plateaued and at best was average. I also bought a number of brewing books which although a number were very good the time taken to reach mediocrity has been a good couple of years. Having invested several hundred pounds in equipment over this period I decided to reach out to The Hop Doctor to arrange a 1:1 session.The two sessions were fantastic
As well as brewing at commercial scale I also brew at home, but my approach is unusual. Brewing is my second career, and I have taken what I learned at commercial scale and through my IBD professional training and scaled it down to the 23 litre scale. Whilst the internet can be a great resource, there is a great deal of inconsistent and incorrect advice out there. I can bust those myths for you and explain the process based on the latest proven scientific understanding as gained from my IBD Brewing Diploma, commercial experience and my background as a Ph.D chemist.
Advanced Home Brewing – Theory & Practice
Half day of theory (with course notes to keep)
Shadowed Brew Day with professional advice and Q&A session
Cost: £235 for any location within 40 miles of the BB7 postcode
Other locations considered, travel costs at 75p / mile
Professional recipe design (for home use)
Recipe for 5 gallon system plus one recipe iteration (based on your thoughts on the first brew) within 3 months of initial recipe provision.
Cost: £45 (only as an addition to the above)
Spend a day with The Hop Doctor!
Thanks to Will for sharing his amazing level of professional knowledge which would have truly taken me years to learn. I’d highly recommend anyone from novice to intermediate home-brew hobbyist to contact him as I feel the small investment in myself was, is and will be enjoyed for years to come.
My last post on hop addition timing attracted a lot of interest and someone from Yakima Chief reached out to me with a technical data-sheet which they published in 2021. I’ve shown the key chart below which quantifies the nature and level of hop flavour oils which they have detected in a finished beer vs. species and addition time.
They don’t specify their methodology but compare a set of hop species whose oil content has the combination of concentration and properties (solubility, boiling point etc) which helps them to remain in the beer from the hot side and those whose qualities mean they are best added as a dry hop.
Species
Flavour / Comment*
2-Nonanone
Cheesy / Herbal
Geraniol
Floral
Linalool
Citrus / Fruity
2-Methylbutyl isobutyrate
Fruity / Apricot
Methyl Geranate
Floral
Isoamyl isobutyrate
Apricot / Banana
3-Mercaptohexanol
Tropical / Grapefruit
* A flavour combination is often different from the sum of it’s parts.
Information of hop oil composition is hard to find, so whilst the chart is only qualitative and only covers US varieties it does give a good guide to a range of 20 popular aroma hops. I know that one use I will be able to put this to is to combine hops with different oil profiles to better maximise the breadth of flavour experience in my beers.
A copy of the full data-sheet can be downloaded from here or here. If you are a micro-brewery wanting help with a beer design, please do get in touch and let’s see how I might help.
Is it possible to rationalise the best time to add specific hops into the wort boil? Not simply to maximise their bittering potential (that’s simple), but to extract and retain their flavour potential. This is the question I asked myself. Brewing is my second career, I started my working life as a problem solving chemist underpinned by a Ph.D in chemical mechanisms. Thus it has always been useful to me to understand the reasoning behind how a process is run. The why behind the what. So whilst it’s clear that late addition hops will lose less of their essential oils to evaporation, would it be possible to come up with an overall theoretical basis for which any hop flavour is best obtained at specific times within the boil? (not just the trendy ones.) I think the answer is yes.
I’ll not squander your time on the ideas that didn’t work and cut to the chase. When I drew up a list of all the essential oils which I could name if was clear that different flavour classes fell into different chemical functional group classes. i.e. All woody and spices flavour oils are higher molecular weight (MW) hydrocarbons or oxidation products of these. Citrus flavours come from low molecular weight (C10) unsaturated terpenes / terpene alcohols and so on. Here is my list of those chemical classes:
Aroma / Flavour
Chemical class
Spicy / Herbal
Oxidation product (high MW)
Woody
Oxidation product (high MW)
Purely spicy
Oxidation product (low MW)
Passion Fruit
Thiol
Tropical Fruit
Thiol
Citrus
Unsaturated oxygenate
Floral
Unsaturated oxygenate or Biotransformate
Pine
Terpene
Resinous
Terpene
Grassy
Aldehyde (low MW)
If you then list the oils by boiling point, the rationale behind their use starts to becomes clear.
So what do we learn?
Hop derived traditional British beer flavours can survive from the first wort hop additions because of their high boiling point.
In general spicy herbal flavours are likely to require a reasonable length of time in the boil to facilitate their oxidation to epoxides, probably at least 20 minutes.
Experience suggests that oils with a boiling point below 230 C are readily lost and should be added at the whirlpool.(1)
Flavours from biotransformation are best achieved by dry hopping or whirlpool additions.
Add to the above knowledge the very low concentration of thiols present in hops and you can see that tropical flavours are only likely to be obvious from whirlpool or dry hop additions.
On these basis we can rationally add hops into the wort at the point which will maximise the flavour component we are seeking. So take Perle hops for example, which can offer both spicy and orange flavours. The spicy flavours would be best gained by adding in the flavour section to (+20 / +30 min) to allow time for oxidation. However, if we want the pine / orange flavours from this hop then this would be best achieved at the whirlpool. Observations such as this explain why the addition of the same hop at different stages of the boil can give a greater breadth of flavour to the beer. The same is true with dry hopping where additions during active fermentation should be expected to yield more biotransformation flavours that those added during warm conditioning. Thus a rationale for double dry hopping, but only if the correct hop varieties are used (those containing Geraniol / Linalool). Although I still suspect that the DDH moniker is more of a marketing term than a zymological one.
What I’d like to do next is to tabulate the flavour threshold of all of these oils to see what extra insight this sheds into the area. Highly experienced brewers are likely to have come to the above conclusions simply through their breadth of experience, but I know I’ve found it satisfying to bring some rational (ab initio) light to shine on this question.
All through the brewing process, having your mash liquor, wort and proto-beer within the desired pH window is critical to both quality and yield. When we are mashing or fermenting we are relying on enzymes which work best within a tight pH window. During boiling it is chemistry rather than biochemistry which is at play, but still pH is critical to the final beer quality.
The chart below shows the ideal pH window as it tracks through the whole brewing process.
Mashing
During the mash we want the α and β amylases to work as effectively as possible and that means that the mash should be between pH 5.2 and 5.4. This is controlled primarily by your water chemistry which I covered in an earlier post. If your pH is too low your starch conversion efficiency will drop, if it’s too high you’ll start to extract tannins and silicates which you want to leave behind in the spent grain. If you are running a new recipe it’s wise to check this pH on the first couple of runs to make sure it within range. This is doubly important with darker beers, where the roasted malts can have a big impact on the pH. There are ways to estimate this, but they are only estimates and it’s best to check what you’ve achieved and adjust your calcium or bicarb addition levels on porters and stouts. After that it’s good to check your run off pH once a week / fortnight to check nothing has drifted.
That astringency that you taste in some stouts, it shouldn’t be there! That is someone not properly attending to their mash pH.
Mashing is the stage where pH is most critical, if you get inside the correct window here then it should track within the desired window for the rest of the process for beers above 3.0% ABV.
Sparging
Here you should be using either pH or SG to monitor your last runnings so as not to go too far. That last portion of weak worts doesn’t contain a whole lot of sugar but will contain undesirable levels of polyphenols or lipids if you let the pH go above 5.8 or SG below 1.006. Remember you are sparging with water which will be pH 7 or slightly above, so the pH of the run off will start to rise from the middle of the sparge onwards
Boiling
There’s a lot that goes on in the boil. The pH will impact the colour development, hop α-acid isomerisation and protein drop out (thus final haze stability). Different pH’s are ideal for each, so the key here is consistency. The pH drops during the boil due to the acid end products of the Maillard reaction and more Ca phosphate precipitation. If necessary you can add a little phosphoric or lactic acid during the boil if the pH is outside of your normal range. However if you have got your mash pH correct and not over-sparged you shouldn’t have an issue. If you are making a low alcohol beer you are likely to need to add a little acid to drop the pH into range.
Fermentation
Again we are trying to keep the enzymes happy and so long as we’ve done everything right up to this point all should be well. Yeast produces acids as a by-product of cell growth and also as one of it’s sugar transport mechanisms. One key thing to remember is to drop the yeast, or transfer the beer off the yeast in a timely fashion or you’ll see your pH rise, reducing shelf life as well as adding undesired ‘beefy’ flavours to your beer. If you are making a low alcohol beer again extra care should be taken and the pH adjusted if necessary.
pH measurement
After spending 20 years in the chemical industry I know more than a little about temperamental pH meters. If you are going to buy a pH meter don’t skimp on price or pick the cheapest one you can find on Amazon. These will never be as accurate or repeatable as you’ll need for brewing. Something from Myron or a bench based model from Jenway would be good options. If you cannot spend £250 then your better option would be to get some narrow range pH test sticks (try these or these). These may not be as precise but if you want something inexpensive yet accurate they are your very best option. You can know for sure if you are sitting inside your desired range or when to stop your sparge. They are quick too.
Hop Doctor 