Breweries working with « high gravity » are experiencing recurring problems with unfilterable and persistent hazes even at 20°C. Classic treatments such as proteolytic enzymes or clarifying agents have not been successful.
We offer an enzymatic solution, Labilase, that can decrease this unfilterable haze by +/- 50% after a 24-hour contact in the BBT or maturation tank. The enzyme is deactivated during beer pasteurization. This treatment does not affect the organoleptic properties of the beer including foam stability.
Labilase is an enzyme complex that is active even at low temperatures encountered during maturation or in BBTs. It is efficient against unfilterable haze excreted by the yeast and is deactivated during beer pasteurisation.
The following table shows the results of three different breweries producing beer with different original gravities and different fermentation temperatures. The average turbidity values correspond to measurements taken in filtered beer at the output of 100 maturation tanks. Another 100 maturation tanks were treated with Labilase at 0.25 g / °P of original gravity / hl to compare the average turbidity with the non-treated tanks.
|
|
Original gravity in °P |
Fermentation temperature °C | Turbidity EBC 90° |
Turbidity EBC 90°Labilase |
|
Beer A |
16 | 12 | 1.2 |
0.60 |
|
Beer B |
18 | 12 | 1.3 | 0.65 |
| Beer C | 15 | 16 | 1.8 |
0.75 |
The enzyme complex Labilase allows you to hit your specifications even in case of unfiltrable hazes. Labilase in no way affects beer foam stability, body or taste.
Another alternative we suggest to brewers is to treat the beer along with regular colloidal stabilization. If the turbidity values measured in the bright beer tank are too high, the brewer can still use Labilase at this step. After a contact time of 24 hours the unfilterable haze will be reduced to more acceptable values.
To understand the root cause of this unfilterable haze, let’s first examine the morphology of yeast cells, and more specifically their cell walls.
The yeast cell is physically protected from the outside by a wall which thickness varies according to its physiological stage. The wall thickens in the stationary phase (absence of growth) and begins to thin during the latent phase at the start of fermentation. During the exponential growth phase, the wall is greatly reduced to allow multiplication by budding. This wall guarantees the integrity of the yeast’s morphology and osmotic stability. At the end of the exponential growth phase, the cell wall begins to thicken, protecting the yeast cell until it is again in the presence of nutrient conditions favourable to further multiplication.
The cell wall is semi-permeable, allowing controlled transport of molecules up to 600 Dalton, water, ions, etc. The weight of the cell wall represents about 20% of the cell’s weight. The precise macromolecular structure of the yeast cell wall remains unclear. The yeast cell wall is 90% polysaccharides, glucans and mannans, and also contains proteins, lipids, phosphates and minerals. This complex structure is composed on the inside of several layers of glucose polymers (beta-gucans 50% beta 1,3 and 8% beta 1,6) which form a network of fibrils that give the wall its strength and flexibility. It is also made up of mannoproteins (40%), most of which are located towards the outside of the wall, but there are also some towards the inside of the wall, anchored in the cell plasma membrane and serving as anchors for beta-glucans (see Figure 10). Mannoproteins are linked to beta-glucans by covalent bonds. These mannoproteins are more like proteomannans, since the mannan portion generally represents over 80% of the molecule’s mass.
This wall also contains a small amount of glycogen.
Glycogen is the yeast glucose storage polymer closely related to starch, or rather amylopectin.
The presence of glycogen in the yeast cell wall could be considered as purely academic interest, but far from it. Glycogen can cause problems of permanent, unfiltrable colloidal haze, resulting in beers with unacceptable turbidity values (Malcorps et al, Glycogen released by the yeast as a cause of unfilterable haze in the beer, 2001, Technical Quarterly, Vol. 95, pp 95-98). This glycogen can be released into the medium when the yeast is confronted with stressful situations such as high gravity fermentations and high alcohol contents. During fermentation, yeast cells settle to the bottom of the fermenter, die and undergo what is known as autolysis. Autolysis is a complex enzymatic self-degradation of cell constituents that begins immediately after yeast cell death. Among other things, it leads to the release of glycogen into the fermenting beer.
Beer cloudiness due to glycogen is said to be permanent because it remains when the beer temperature rises to 20°C, unlike the classic reversible cloudiness (polyphenols/proteins) which is a cold haze that disappears when the temperature rises. At the time (2001), Malcorps et al had not found a solution to eliminate this unfiltrable haze. In the meantime, CBS Customized Brewing Solutions filed a patent (Patent WO20128117A1) for an enzymatic treatment Labilase of beer in bright beer tanks (0-5°C), which was capable of reducing this unfiltrable haze by 50% in 24 hours, without altering the beer’s organoleptic qualities, and bringing the cloudiness values back within specification standards.
Patent WO2010128117A1 https://patents.google.com/patent/WO2010128117A1/fr
For more information please contact our technical team: technicalteam@cbsbrew.com