Before
mashing in the cool box mash tun it should be thoroughly preheated before use,
this makes stabilizing and maintaining temperature a lot easier during the mash.
To preheat, just add a couple of kettles of boiling water and the allow the mash
tun to sit with the lid on for 15mins, this is one of the most important steps
as it helps the mash temperature to remain constant throughout the duration of
the mash and also makes minor adjustments at the beginning a lot easier. While
the mash tun is warming up, in your boiler heat up enough mash liquor (water)
for the required water/grain ratio (1)
up to 'strike heat' (2)
.
Next drain the mash tun and add the mash liquor, once the temperature has stabilized at strike heat (add cold or boiling water as required), slowly pour in the grains while gently mixing or doughing in (3) . Make sure any lumps are broken up and there are no dry spots, the final mash will look like a gritty porridge. Stir to ensure an even temperature through out and take a temperature reading, it should be close to the desired mash temperature (4) . If it is too high, then slowly add cold water to lower it. If it is too low, slowly add a kettle of boiling water to adjust the temperature (5) accordingly. It's useful to have a kettle of boiling water and a jug of cold water ready before doughing in so the temperature adjustments can be made without delay.
Once the temperature is stabilized, put on the lid and cover the mash tun with old blankets or sleeping bags to help maintain a constants temperature throughout the 90 minute mash period (6). (Take a note of the time). If this is the mash tuns first use, have a kettle of boiling water ready and check the temperature halfway through to check if it has dropped at all. If it has, this isn't a problem, rectify by slowly pouring in the boiling water mixing well and taking regular readings aim to adjust the temperature (5) in the same way as before. Once the performance of the mash tun has been determined it may not be necessary to check halfway through the mash. A temperature drop of 1-2 deg over the mash period is quite acceptable and can be ignored, much more though and extra insulation may be required or the temperature will need restoring halfway through.
During the mash, the sparge water should be prepared. Heat up a similar volume of water to 80 deg c to that of the final volume of wort be fermented (so if brewing a 23L recipe heat up around 23 L of sparge water, it's better to discover you have too much rather than too little). Once the 90 minutes is up the wort must be seperated from the grains, this is known as lautering. The copper manifold in the bottom of the cool box mash tun holds back the grain bed which in turn filters the larger particles from the wort as it is drained or run off from the mash tun. Open the tap a small amount and let the wort drain slowly from the grains, initially it will have particles of grain in it so the first few pints should be collected in a jug and gently poured back over the grain bed for filtering. Once the wort is running free from particles, it can be collected either in a separate collection vessel (7) or directly into the boiler.
Once lautering is underway and the liquid level begins to drop, gently add the sparge water from the hot liquer tank (HLT) to rinse the remaining sugars from the grains, this is known as sparging. The water should be added carefully and evenly so not to disturb the grain bed and the water level should be kept just high enough to keep the grain bed a-float. A watering can fitted with a rose can be used so to gently sprinkled the water over the grains although a jug will do if it's done carefully. Run off should be done slowly to avoid compacting the grain bed causing a stuck mash (8), like wise the liquid level shouldn't be allowed to drop too low either. If a stuck mash does occur the grain bed can be re-floated by flooding it with sparge water, any blockage can be cleared by blowing back up the tap. If this fails to clear it then the grains can be stirred. When run off starts again, as before the first few pints should be returned back to the mash tun for filtering.
Sparging should be stopped once the gravity of the wort has dropped to 1006 (adjusted for temperature), sparging further is likely to extract unpleasant tasting tannins from the grains. The amount of wort collected may or may not be the required volume, this doesn't matter, if it isn't already in the boiler it should be transferred and the boil commenced.
(1) Water to Grain Ratio (quantity), this is usually 2-3 litres of water for every kilo of grain, starting off with a thicker water to grain ratio means more boiling water can be added later should minor adjustments be required. In theory a thinner mash will produce a more fermentable wort but the difference is negligible.
(2) Strike Heat is the temperature of the mash liquor, hotter than the required mash temperature which compensates for the temperature drop that occurs when the cool grains are added. A strike temperature of 72 deg c is usually sufficient to produce an ideal mash temperature of 65-66 deg c with an average grain bill (quantity) of 3 to 5 kgs and a water to grain ratio of 2-3L per Kg.
(3) Doughing In is the mixing of water and grains. It is often useful to premix the grains in a container that can be poured easily such as a bucket to make doughing in easier.
(4) Mash Temperature. This is the temperature where enzymes in the mash convert starch in the grains. Lower temperatures favour the beta amylase enzyme which produces easily fermentable maltose and a dryer beer, higher mash temperatures favour the alpha amylase enzyme which produces much less fermentable dextrin's and produces a sweeter beer. 65-66 deg c will produce the correct ratio of maltose to dextrin for a well balanced English ale.
(5) Temperature Adjustment. Mix the water used for adjustments in well and take regular take temperature readings. To avoid over shooting, aim to make small step adjustments, for eg. if the initial temperature is 63 deg and the desired is 66, aim for 64/65 deg c initially, if your find you haven't added enough hot water and under shoot, then you can add a little more, if you have added too much you will have hit your target.
(6) Mash
Period. This is the period of time the grains are allowed to mash (soak in
hot water) to ensure all the starch in the grain has been converted to sugar and
to get
the right balance of maltose and dextrose. This is usually 60 to 90 mins.
While the starch conversion will be complete before the time is up the extra
time is required to achieve the correct balance of fermentable and unfermentable
sugar as the beta amylase enzymes continues to convert the dextrin's to maltose.
To check for complete conversion a simple test can be carried out by taking a
sample of the wort and putting it on a clean white plate and adding a drop of
iodine or iodophor. If the sample turns purple/black then there are starches
present and the mash should be continued. Make sure the plate is spotlessly
clean, any food residue can also cause the iodine to change colour.
(7) Collection Vessel. If the boiler is also acting as the hot liquor tank (HLT) for sparge water then a separate collection vessel will be required to collect the wort in before transferring to the boiler. Alternatively the sparge water can be prepared in advance and stored in a separate HLT such as an insulated fermenter and the wort can be run off from the mash tun straight into the boiler.
(8) Stuck Mash, usually due to running off too quickly a stuck mash is where the grains compact down onto the filter preventing any wort from flowing. .
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Last Update 18/06/07