by Grégoire Roussel, brewer

Brewing is an exacting and delicate process. To brew a quality beer it's important to study carefully each step of the brewing process - skipping any seemingly unimportant detail can result in a beer without depth. I hope that my insights as brewer at L'amère à boire will be of some help to other brewers.

The brewing process is separated into two important steps:

-the fabrication of wort.
-fermentation.

Because wort is the fermentable material in brewing, the greatest attention must be paid to its production. Yeast cannot fully ferment in the wort if it has some sort of weakness.

The Malt has to be crushed not ground. This will assure a good extraction, a more successful rinsing and the production of a clear wort. The mashing is done by adding the malt to the hot water in an average proportion of 39 kilos per hectolitre. The temperature of the mash must be maintained between 66 and 67 degrees Celsius. The acid level has to be verified and corrected throughout the brewing process. The ideal PH for the mash should be between 5.20 and 5.50. The PH of English ales is corrected by adding calcium sulphate (CaSO4). A quantity of .5g/L is added to the cold water. If the PH of the mash is incorrect, it's not useful to add gypsum because when heated gypsum is almost insoluble. As such it is necessary to use acid to correct the PH. We use lactic acid because it has the advantage of being efficient and not dangerous to the brewer. In fact, the acid level of lagers can only be corrected with lactic acid. The temperature should be maintained for 90 minutes. We add boiling water to raise the temperature of the mash to 76 Celsius. The transformed sugars dissolve better and as a result a better wort. Start to turn the wort until it is clear. The manipulation of the heated wort must be done delicately, avoiding the introduction of air (heated oxidation). Beer wort contains melanoids that are coloured polymers, from pale yellow to dark brown and which contribute to the stability of the finished product. The more roasted malt the beer contains, the higher number of polymers there are. It is important to be sure not to oxygenate the heated wort because when exposed to oxygen the melanoids produce the opposite effect and the beer deteriorates rapidly.

    At this point the transfer of the hot wort to the kettle may begin. Sparging begins with 77 degree Celsius water and ends when the density of the malt is below 3 P. It is preferable to add water if the quantity of the wort is not enough. The liquid is then bought to a boil. The hops are added and the mix is boiled for 90 minutes. The hops we use always come from the same country as the particular style of beer we are brewing. For example, Cernà Hora is brewed uniquely with Saaz from the Czech Republic. This type of hops has the most tannin of any hops available. Tannins give the beer the dry finish important to Pilsners.
    When boiling begins clouds composed principally of coagulated proteins form. The PH should be approximately 5.3. The finishing hops are added at the end of boiling. We use hops leaves which, when straining the hot wort towards the cooling coil, act as a natural filter, essential to obtaining a clear wort.

    The wort cools to 8 degrees Celsius for lagers and 18 degrees Celsius for ales. This is the only step in the process where we add air. The wort has to be saturated in air to obtain a good fermentation.

    Pitching the wort with the yeast is done as soon as the fermenting tank is full. The fermentation takes between three and four days for ales and six to ten days for lagers. The temperature, the PH and the density are periodically regulated. When fermentation is terminated, the beer is cooled. Enough yeast is kept for the next brewing. In fact, by working in an aseptic environment it is possible to reuse the yeast for an extended period of time. For example, the Cerna Hora yeast has been used for four years. No test has shown contamination.

    After settling for several days the beer is transferred into a holding vat where it matures. Ales are ready to be served after a minimum of 14 days. Some lagers take between 2 and 3 months.

"Images of fermenting lager in the Czech Republic and in Montreal"

20,000 liter vat

Fermenting tub at the Cerna Hora brewery in the Czech Republic

Cernà Hora fermenting at L'amère à boire 6 days after yeast pitching into an "open" fermentor 1000 liter vat.  We can notice similarities of shapes and colors on the top of fermentor from both breweries.

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