Brewing malt the change in season and milling optimisation


Crisp Malt


As the freshly harvested barley makes its way through the Malthouse we want to make sure that you’re prepared for any changes that might be thrown up as you transition from crop 2017 to crop 2018. That’s why we’ve worked with our master maltsters and brewers to prepare this handy guide to the season changeover. This guide is also particularly useful when you change over base malt generally.


As you may well have noticed, this year has been an unusual one in terms of weather. While we all basked in the sunshine the extended period of drought and heat produced an unusual and extreme growing season for our precious barley.

Barley gets planted at two times in the UK; one crop in October/November of the preceding year (referred to as winter barley) and one in the March/April of the crop year (known as spring barley). This year, the winter barley got a good soak in the wet winter and spring and so got an excellent start to growing in the new year. This also meant that when the warm weather did start, the plants had a good water base to survive through the drought.

The spring barley didn’t have as much of a fighting chance. Because the rain was prolonged throughout Jan-March, the grounds were saturated and farmers struggled to get the spring barley planted due to poor ploughing conditions and flooded fields. The warm weather started soon after this and so the spring barley plants didn’t get a great start and struggled through the drought.

Fortunately for Crisp, the North Norfolk area around our Great Ryburgh Maltings is well suited to winter barley. Indeed, we’ve been working with local farmers to grow barley locally for almost 150 years. While this is a relatively small crop in the wider UK market, we’ve found it to be very reliable for making ale malt and once again it has returned a good crop with all the key characteristics for producing excellent beer; namely low nitrogen/ protein and good starch levels for extract. Winter barley requires less water and also helps to reduce erosion by stabilising the soil over the winter months.

This all being said, the hot weather has meant that there were simply less barley plants that came to maturity and the result is a drop in yield for both winter and spring crops. This has been mirrored in crops across Northern Europe, coupled with additional demand for feed leading to significant increases in the European grain markets. We have minimised these through having strong relationships with our all-important British farmers up and down the UK.

What’s changed?

Our lives as maltsters, brewers and distillers would be much simpler if the barley didn’t change from year to year. While we do our utmost to iron out inconsistencies from crop to crop, there are always going to be subtle changes in the biology of the plant which can affect the way the malt behaves in the mashtun. We’ve written up some of the changes that we see in the barley and how they might affect your brewhouse practices.


Corn size

The corn size can vary depending on the variety and weather. We are looking for plump grains that will take up water well in malting. At Crisp we remove the small corns (another that passes through a 2.25mm screen) and this ensures we get an even malting of the batch. If the corn size distribution has changed it means the milling might also change. On the bagging line we are constantly checking the grist fractions by performing a sieve analysis. If you mill your own malt then this is a simple test that you can also perform. Too much milling and you could end up with higher extract, over attenuated beers and a stuck mash. Too little milling and it will be lower extract and you will be leaving sugars behind in the grain. Take a look at our quick guide on how to optimise your grist.


Friability is a measure of how easily the malt will mill. The more friable the malt the less energy required to break it apart. We often see malts from the continent and some part of the UK with poor friability (in the 80s). We would ideally want friability to be in the 90s. This is an indication of good malting practice. A change in friability means your mill setting may need to be adjusted. As mentioned above, we recommend a simple grist analysis to check your milling is optimised.

Nitrogen/ Protein Level

The barley plant can put its energy into making starch or protein, more commonly referred to in the UK by its base element nitrogen. Generally, when the nitrogen goes up, the starch goes down and we lose extract. There is a very specific sweet spot for ale and lager malts for nitrogen content, namely 1.4-1.6% N2 for ale and  up to 1.75% for lager.

A good practice at the changeover in season is to optimise your kettle finings. This will ensure you’re taking enough protein out of the boil which will help with yeast health and also ensure bright, shelf stable beers. Contact your finings supplier such as Murphy & Sons for advice on performing the simple finings optimisation tests.


As mentioned above, the extract may vary due to the protein content of the malt. We work very hard to ensure a consistent extract from season to season and throughout the year. It’s always good to periodically read your certificate of analysis to check if the extract has changed. You should always work with the “AS IS” extract not the “DRY” extract for making gravity calculations. If you’re unsure of working out target gravity we can provide a handy calculator spreadsheet.

Diastatic Power (DP)

The diastatic power is a measure of the enzyme activity in the grain; the higher the DP the quicker the conversion rate from starch to sugar. A discussion of controlling in enzymes in the brewhouse is lengthy but if your DP has increased (by a certain % or amount?) then you may have to increase your mash temperature or decrease your mash time. It might be a good idea to carry out a starch test using iodine to check that you have full conversion of starch into sugar. As soon as this process is complete you can run off.



At Crisp we monitor the grist fractions on every single batch of crushed malt that passes through our mill. It is only by doing this, that we can optimise the balance between run-off and extract for our brewers and distillers. We do this by using a simple grist box as shown. If you mill your own malt then this is an essential test to perform every few weeks and especially when moving from one crop season to another, or from one base malt to another.

The method is simple:

  • take a representative sample of grist from your mill
  • place about 100g of grist in the box, replace the lid and shake for 2 minute from side to side
  • weight out the fractions in each layer of the box (we find a soft bristled paint brush helps get all the malt out the box)
  • Sum the weights to arrive at a total and calculate the % fractions in each layer of the box.

These are the fractions we work to at Crisp for crushed malt but if you operate a lauter tun then you may wish to go a touch finer

Sieve Crisp Base Crushed Malt Spec Crisp Distilling Spec Lauter Tun Spec
Coarse (above 1.98mm screen) 50% 20% 40%
Fine (below the 1.98mm screen) 40% 70% 30%
Flour (below the 0.212mm screen) 10% 10% 30%


Regular maintenance of your mill, including monitoring of the wear on the roll pack will ensure consistent mill performance.

If you’re in any doubt about your milling performance then please speak to our technical team who will be happy to assist.