mäsktillväxt

Mäsktillväxt refers to the process of yeast growth during the mashing phase of brewing. Mashing involves steeping malted grains in hot water, a process that converts starches into fermentable sugars. Yeast, while not actively fermenting during this stage, can still grow in the mash if conditions are favorable.

This growth is primarily driven by the presence of readily available nutrients and a suitable temperature range. Although the main yeast pitching occurs after the wort (the sugary liquid extracted from the mash) is separated and boiled, a small population of yeast can proliferate within the mash itself. This can happen if wild yeasts are present or if residual yeast from previous brewing cycles contaminates the mash tun.

The temperature of the mash plays a critical role. While optimal temperatures for starch conversion are typically between 60-70 degrees Celsius, yeast growth generally thrives at slightly lower temperatures, often in the range of 20-30 degrees Celsius, depending on the yeast strain. If the mash temperature accidentally falls into this range for an extended period, and if nutrients like free amino nitrogen (FAN) are abundant, yeast can begin to multiply.

While some minimal yeast growth in the mash might not be detrimental, excessive mäsktillväxt can potentially lead to undesirable flavor compounds being produced before fermentation even begins. Brewers typically aim to maintain mash temperatures that favor enzymatic activity for sugar conversion and then quickly cool and separate the wort to initiate controlled fermentation with the desired yeast strain. The primary goal of mashing is starch conversion, not yeast cultivation.