The mash is where the magic starts and the starches found in the grain are turned into fermentable and unfermentable sugars. This is done by enzymes which break the chains of glucose which make up the starch, these enzymes are called beta amylase and alpha amylase and it is primarily these two enzymes at work in your mash. They both work together to break down the starch in the mash. Alpha amylase can be described as breaking the starch chains in half which are then broken down further by beta amylase which nibbles at the ends of these already broken chains. The starch is broken down into a range of sugars including glucose, maltose and maltotriose. However parts of the starch remain intact and this is what forms some of the unfermentable dextrins which add sweetness, body and mouthfeel to a beer.
Each enzyme has a certain temperature range it prefers which helps brewers create specific beer styles. Alpha amylase works best between 68-75 C creating sugar chains which are less fermentable, along with maltose and unfermentable dextrins this then makes a beer with more body. Beta amylase works best between 54-65 C and breaks the sugars down further, mainly into maltose, making them more fermentable achieving higher attenuation and a thin body. Therefore the general rule is that a lower mash temperature will create more fermentable sugars and a thinner body, resulting in a lower FG, a high mash temperature will create less fermentable sugars and give a high SG. Both enzymes work to an extent in the temperature range 64 – 70 degrees c. Some brewers mash using both temperature ranges for both enzymes and therefore achieve a higher level of starch conversion resulting in a crisp and dry beer. This process is often used to make lager.
These two enzymes also prefer a different mash PH with Alpha amylase preferring a higher PH of between 5.3–5.7 and beta amylase preferring a PH of between 5.1–5.3. This along with the mash temperature can result in the brewer achieving a different style of beer. Altering the PH of your mash must be done by altering the PH of your strike water first. This is a trial and error method to be perfected over numerous brews until it’s right.
Enzymes exist in the barley seed to help provide nutrients as the seed grows. Maltsters stop this enzyme production when it is at it’s peak and they remain in the grain until it is mashed.
This is where the grains are mixed with the water you need to ensure that there are no dough balls for easy conversion of the starch to sugar. Some brewers like to start this at a lower temperature between 38 – 49 degrees C called the dough in rest which enables the enzymes that work best at lower temperatures to start breaking up the starch chains into sugars. This isn’t a step I have done as I get the water to mash temperature first and then add the grain, however beer making is full of different kinds of methods that can potentially improve the efficiency and flavour of your final beer.
The next step after the dough in this is done at temperatures between 44–60 degrees C and is another incremental step in the mashing process allowing certain enzymes to do their job. Again, though, this isn’t a step I have done before so you don’t need to worry too much it’s just an option to try when experimenting with beer making.
Saccharification (Conversion of starch to sugar)
This is the main show where you can mash anywhere between 60 and 70 degrees depending on the desired type of beer, low temperatures for thinner beers with higher attenuation and high temperatures for beers with a fuller body and more malty flavours. The most common mash temperature is around 67 degrees C where both alpha amylase and beta amylase can work.
Raise the temperature to 74 degrees or higher where enzyme activity is not possible for five to ten minutes to preserve your sugar profile.
You can check the starch conversion of your mash by doing an iodine test. Take a sample of wort that doesn’t have any grain particles in it and add a few drops of iodine, if there is any starch present this will turn black. Otherwise the colour should be a reddish colour or a strong red colour for a wort that has been mashed at a higher temperature and therefore has more dextrins present.
Hope this little guide helps and if you have anything to add let us know, brewing is a constant learning curve : ) Cheers!