How to roast your own malt
By Dr J C Harrison
There are several reasons why home brewers should consider home-roasting malted barley.
In Victorian times there were a number of grades of roasted, or over-kilned, malt that were widely used to impart desirable flavours to beers. Some of these e.g. pale amber, high amber and brown malts are difficult to obtain and even stalwarts such as mild ale malt and mid-amber are getting scarce. Even when a particular grade of malt is available commercially e.g. carapils (caramalt) homebrew shops may decline to hold stocks because of low demand. Another reason is that freshly roasted malt, used soon after production, has a better aroma and flavour than roast grain kept for some time.
One consideration that needs to be taken into account when grain roasting is how the roast malt is to be used. If used in small amounts as a flavouring with large amounts of pale malt the enzyme content of the roast malt is not important and quick roasting methods can be used. If however the ~ malt constitutes the major part of the grist (as with some amber ales) then retention of brewing enzymes is essential. This needs a long pre-drying of the malt followed by a gentle roasting schedule. It is difficult to roast malt to an EBC (European Brewing Convention) Colour Number exceeding 50 and retain enzymes.*
Equipment
A medium-charge oven preferably with fan stirrer.
Large stainless steel roasting dishes (preferably 2).**
An accurate thermometer, range 50"-200', that can be left in the oven.
Spoon for stirring the mait.
A sharp knife e.g. Stanley knife or razor.
A4 size white card.
Portable lamp with a daylight bulb.
In non-fan stirred ovens there are advantages in using two trays of malt, one close to the top of the oven, another 3 - 4 inches lower. The top tray roasts quicker than the lower tray so initially one can check just the top tray. Should this overshoot slightly, mixing it with the lower tray should even the colour numbers out. It is, of course, not essential to use stainless steel trays. Normal, clean, raasting tins lined with baking foil are ideal for the beginner or occasional roaster.
Checking The Colour
The simplest equipment for measuring the EBC colour number of grain costs about £500. Durden Park has the equipment but it takes approximately 2 hours to produce a value and this is too slow to control the roasting process. This has to be done as follows:
On the white card fix a 3" length of double-sided sellotape. Take 15 assorted corns of pale malt, slice them in half crossways with the knife and stick them on to the sellotape with the cut faces forwards. This provides a benchmark against which to compere samples taken during the roasting process. These should be cut in half as above, lined up close to the pale malt and the average colour compared with the benchmarks. Particularly with the palest roast samples this requires bright daylight or a daylight lamp. A few corns darken prematurely. These should be ignored when making the comparison.
Traditionaily, maltsters often used a pestle & mortar to grind up a few grains to check for colour. A modern version of this would be to use a small coffee mill or grinder. This may require the waste of more grain but can be easier and also evens out the colour variations of individual grains.
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METHOD 1: QUICK ROAST |
METHOD 2: SLOW ROAST |
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Fill the stainless steel pan 1" to 1.5" deep with malt. Place near the top of the oven pre-heated to 95C- 100C. Dry the grain with occasional stirring for 45 minutes then raise the oven temperature to 150C. When the oven temperature has stabilised, stir the malt and check colour. Stir and check the colour every 20 minutes until the desired colour is reached {see table 1). Remove from the oven, cool and keep in airtight. containers. |
Repeat the procedure for the quick roast but dry at 95C-100C for 2 hours. Stir and raise the oven temperature to 110'C for one hour, stir and check colour. Raise oven temperature to 120C. Stir, check colour. Raise oven temperature to 140C and insert the thermometer into the centre of the malt. Pale amber colour is normally reached when the grain temperature is in the range of 120C - 125C. |
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Grain Colour Vs Type | ||
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Type |
Average Colour of Cut Corn |
Approx. EBC Number |
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Pale Amber |
Palest buff |
30 - 35 |
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Amber |
Distinct light buff |
60 - 70 |
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Brown |
Full buff/ Pale brown ( colour of pale brown envelope) |
140 - 150 |
