mex lager

The best results will be achieved by pitching the yeast into cold and well aerated wort (48-58 °F, 9-15 °C).

A secondary fermentation at a temperature below the primary fermentation allows for a slow reduction of any remaining fermentable sugars. This secondary fermentation can take from one to three weeks at temperatures starting between 39-41 °F (4-5 °C) and slowly falling to as low as 33 °F (1 °C). The length of the secondary depends on the amount of fermentable sugars remaining.
During fermentation the yeast produces several different compounds, one considered an off flavor is Diacetyl, which gives a buttery flavor to the beer. During primary fermentation the yeast has the capacity to remove diacetyl. Since it is temperature dependent a raise will increase production, or the yeast will breakdown diacetyl into acetoin and 2,3-Butanediol at the middle of the primary fermentation.

Diacetyl reduction also takes place during secondary fermentation. Depending on the beer profile standard, once the fermentation process reaches 40 to 50% attenuation the temperature is raised 3 to 5 degrees to allow the yeast to reabsorb the diacetyl and break it down to Acetoin, then into 2,3 butanediol. After determining there is no more diacetyl present, the beer cooling process starts. The diacetyl rest may take 6 days after raising the temperature at 56 °F (13 °C). The beer should be evaluated at this point to determine that it is not perceived or sensed.

Lagering is a time when harsh flavors from fermentation are mellowed. Yeast re-absorbs some of the ester compounds from fermentation as well as some of the sulfur compounds. Malt tannins coagulate with haze-forming proteins and precipitate out along with some sulfurous compounds.

Temperatures should remain very stable during lagering, generally in the range of 33-34 °F (1-2 °C). Contact with oxygen at this point is very detrimental to beer flavor and should be avoided at all costs. Lagering time depends on many factors. If a cold secondary fermentation was employed, then the length of the lagering period can generally be decreased. A lagering period of one to four weeks is typical.

During maturation a head pressure of 14 PSI (1 Bar) should be kept at all times.