There are many ways to brew low, or non-alcoholic beers. The alcohol can be removed after the beer is created, or alternatively, the production process can be altered so that the beer produced is already low or non-alcoholic.
The de-alcoholising methods are highly effective and create beers with near-zero alcohol concentrations, but they require significant investment in equipment, which limits these methods largely to industrial breweries.
Craft breweries tend to focus on the production of low-alcohol beers using processes they are familiar with and equipment they already have, modifying certain stages of the brewing process, such as the composition and thermal steps of the mash, the temperature and the duration of fermentation.
AEB offers solutions to help brewers tweak each step of the process to help them create desirable low-alcohol beers or non-alcoholic beers (<0,5%ABV).
In the mashing phase, the composition of the malts can be varied to produce a lower fermentable sugar content.
The desired low alcohol content of the end product can mean a considerable loss of body, but this can be compensated by adjusting the grain/water ratio.
Different cereals can be used in the mashing process to limit and control the saccharification potential of the wort. These include:
This choice is purely down to the brewmaster, who must take care to ensure that the composition of the mash does not produce imbalances in the flavour or alter the desired beer style too much.
The temperatures used in mashing are a fundamental factor in guiding the wort towards greater fermentability, or vice versa to create beer with more body and mouthfeel. The temperature steps in the mashing phase must be calibrated to avoid the temperature sitting at 54-68°C where beta-amylases are more active, and to bring the brew to the optimal temperature for alpha-amylases (72-74°C) to be activated. Staying in the alpha-amylases temperature range will result in a beer much richer in dextrin, which contributes to a lower level of alcohol development.
TEMPERATURE STEPS IN MASH TO OBTAIN OPTIMAL ENZYMES ACTIVITES
To create a non-alcoholic beer, the most common method is interrupted fermentation (combined with the alterations in the mash phase if necessary). The normal fermentation process starts after pitching the yeast, but it must be kept under careful control so that fermentation can be interrupted and stopped when the desired alcohol level is approached. Temperature is also a key factor in fermentation – it should be carried out at the lower end of the temperature range, between 11°C and 16°C.
Clarifying the beer through clarification aids such as silica sol helps to halt the fermentation process, especially if it is vigorous. Products based on silica sol such as SPINDASOL SB3, help with the sedimentation of yeasts and the reduction of haziness.
Halting fermentation can be done through cold crashing, where the temperature of the beer is brought to between 0°C and 1°C and held at that temperature constantly for at least a week. The low temperature deactivates the yeast, and the residual yeast that has accumulated at the bottom of the fermenter can then be easily removed.
Interrupting fermentation and other methods of producing low alcohol or non-alcoholic beers can result in poorer aroma and flavour in the end product. However, with cold crashing, the aromas generated by hopping and dry-hopping are preserved.
Adding aminoacidic nutrition to the wort is essential to increase the aroma profile.
Some specific aminoacids are precursors of fermentation-related flavour-active compounds, which therefore nourish yeast and promote the production of pleasant fermentative aromas such as esters and secondary alcohols. In some cases the excess of these aromas may give unwanted notes to the beer depending upon the beer style brewed, but AEB research has developed nutrients with a fully balanced amino acid composition, whereby only the desirable fruity and floral notes are enhanced.
The strain of yeast chosen depends on the style of beer desired. However, the characteristics of a classic ale or lager yeast may not be ideal for a beer that has undergone changes in mashing or hopping and has a lower alcohol content. In this case, alternatives like aromatic yeasts can be considered.
The aromatic yeasts in the AEB range are excellent used in conjunction with interrupted fermentation. If used in combination with the correct nutrient, they create distinctive warm and enveloping notes of ripe fruit, or fresher notes of tropical fruit, or even citrus, depending on the strain chosen.
These aromas are intense and complex, meaning that a good aromatic profile is achieved, even with partial fermentation.
After the fermentation phase and cold crash are over, it is advisable to filter the beer in some way, especially if you decide not to pasteurise it. Filtration is best carried out with a membrane of a pore size of less than 0.45 micrometers. This ensures the biological stability of the beer before bottling avoiding contamination by beer spoilage bacteria, wild yeasts or residual sediment from the production phase.
A critical element of the filtration step is that it must be carried out in isobaric pressure-stabilised conditions, to avoid the loss of CO2 and pressure. It is important to note that the beer should not be re-fermented in the bottle, because this causes over-carbonation that may lead to a potential explosion of the bottle during its storage at warm temperatures (e.g. on store’s shelves).