Wort filtration is a very important step in the brewing process, i.e., in the production of beer, whether industrial or artisanal. Filtration enables the mechanical separation of solid components from the liquid in which they are dispersed.
A filtered beer is easier to digest and according to some experts, the taste is fuller as it is not affected by the yeasts. In fact, wort filtration is carried out in order to separate the yeast brew deposits that remain after secondary fermentation. Let us take a look at the most commonly used methods.
“Fly sparge” is a technique whereby water at 78° C is poured over the grains in the Mash Pot while the wort is being filtered.
All that is needed is a simple colander and a container to pour the water into, being careful of burns. Alternatively, specific tools can be bought in specialised shops.
There are two main tips for Fly Sparge, namely not to break the bed of grains formed inside the pot and not to uncover the grains. In fact, it is necessary to generate a constant flow of water to replace that which has already been filtered, avoiding oxidation of the wort and incomplete sugar extraction.
The Batch Sparge method consists of pouring water into the Mash Pot only when all the grains are separated from the wort. Precisely, after the first filtering of the wort, the water is poured in at 78° C, the grains are stirred, and a second filtering is carried out after waiting about ten minutes.
Batch Sparge is used to simplify the procedure and avoid the creation of “preferential flows”. At the same time, however, it exposes the grains to air, and consequently increases the risk of wort oxidation.
Which technique to use?
Both of these methods may prove useful for home brewing.
The Fly Sparge may be suitable for those with a larger production, as it allows better recovery of ingredients. Again, this technique allows more sugar to be extracted. However, it is more difficult to carry out, as attention must not only be paid to the bed of grains, but also to the density of the wort, which must never be less than 1010.
The Batch Sparge, on the other hand, may be the most suitable technique for beginners, as it is simpler and there is not a great risk of hitches. The Batch Sparge takes only 20 minutes longer than the Fly Sparge, and no particularly complex equipment is required.
Sparge is not always recommended. One can use what is called the “No Sparge” technique, skipping the stage of washing the grains after mashing. In this case, sweet wort can only be obtained by extracting the sugars from the malt. Generally, ‘No Sparge’ is used for both small production runs and low-density products, but it is not always possible. A larger quantity of malt is required for this technique than for the other techniques. The additional quantity depends on the size of the production plant and the litres to be obtained.
Filters that can be used
There are several methods for filtering beer, the simplest being to precipitate the wort inside a colander contained in the boil pot. Once this is done, it is necessary to wait for the wort to stop dripping, after which it must be sparged with sparge water.
However, it should be made clear from the outset that this method is not recommended as the wort tends to oxidise quickly once it has fallen into the pot; this causes the sedimentation of flours inside the fermenter as well as spent yeast.
The second filtration technique, on the other hand, is based on the use of the Zapap filter, named after an American “homebrewer”. In a nutshell, this filter consists of taking two buckets of equal size (in reality, two fermenters are more than fine), drilling holes no more than 1.5 millimetres in diameter, about one centimetre apart in the bottom of one of the two buckets, and then inserting a tap and trying to thermally isolate the bucket so that it does not exchange heat with the outside.
The filtration procedure is very simple, you have to put the wort with the grains inside the filter, wait about ten minutes for the filter bed to form, take a sample of the wort (possibly still cloudy) from the tap and put it back into the grains using the fly sparge technique. After the wort has clarified, the sparge phase must be carried out with a very slow flow.
The last filter is the “bazooka” and to be able to use it you need a Mash pot, a stainless-steel braided pipe, connected through the hole and with the relevant valves, and a stainless-steel tap.
The procedure is very similar to that of the Zapap filter, however, in this case it is not necessary to pour anything. It is simply necessary to let the mash out temperature rise, wait 10 minutes and then take a sample of the wort and after the wort has clarified, the fly sparge must be carried out to water the grains.