ITM-2浊度计有效实现酵母自动回收

Yeast harvest automation in breweries using the ITM-2 turbidity meter

During fermentation, the yeast pitched into the wort multiplies two- to three-fold through respiration of the oxygen dissolved in the wort. When the wort extract is fully fermented, the young beer is cooled down and the yeast settles in layers on the bottom or cone of the tank. The lowest, densest layer consists of dead yeast cells. The middle and still very dense layer consists of living yeast cells with a high fermenting power known as “white yeast”. The upper layer, or light brown yeast, is mixed with beer and is less turbid. During the fi rst yeast harvest, the bottom two layers are carefully extracted and separated because the white yeast is reused, or even marketed, as so-called “pitching yeast”. During the storage and ageing period, the remaining yeast largely settles out as brown yeast. When the tank is emptied, the brown yeast is carefully separated from the beer as this has a major impact on the beer quality. Many breweries still monitor yeast harvesting manually. The process is controlled by checking the turbidity through a sight glass.