With its optimised yeast propagation GEA offers a system that
guarantees constant quality of the pitching yeast.
Overageing
and mutations of the yeast have an adverse effect on the fermentation process.
Any of these phenomena can be avoided by a propagation of pitching yeast at
regular intervals. In addition, the use of new propagations reduces the risk of
contamination due to repeated yeast pitching. GEA offers a method that ensures
that the yeast is in growth (logphase) during the entire propagation process.
Yeast propagated under these conditions provides high stability in taste and
froth. The reproducible quality guarantees a true pleasure in beer consumption.
The system GEA offers is an optimised "One-Tank-Propagation“ that
conforms to all requirements made on modern process plants.
Basic modules:
- Propagator with cooling jackets
- Circulation loop, complete with heat exchanger (for heat treatment of small
partial streams) and aeration device
- Aeration lance
- Local sterile air station with candle filter and product trap
The Process
During the pitching procedure, wort is pumped in batches into the
propagator. A heat exchanger takes care of increasing the temperature for the
change from pitching to propagation conditions. Yeast is dosed to the heated
wort using a sampling valve. A circulation loop connected to the propagator
ensures optimal mixing and homogenising of the yeast suspension. The
circulation rate and flow velocity may specifically be adapted to the
propagation process and set temperatures. Centrifugal pumps are exclusively
used within the entire propagation system. Aeration of the yeast suspension may
be effected in dependence of the tank contents with an aeration lance installed
in the bottom of the propagation tank. Using the lance offers the advantage
that even with larger product volumes a homogeneous distribution of the air in
the yeast suspension is ensured. Since the amount of sterile air is metered
according to the tank contents and in particular according to the oxygen demand
of the yeast, excessive aeration will not take place. This method significantly
reduces the formation of foam compared to traditional methods and allows GEA
propagators with a headspace of approx. 40% to operate without pressurisation.
Each propagator is equipped with its own fully automated sterile air
station, complete with filter and product trap. The use of local sterile air
filters safely exclude any risk of contamination. The product trap prevents the
product from penetrating into the air system. Highest biological safety is
given because the air pipes are CIP-able up to the product trap.
The
propagator is completely emptied at regular intervals for cleaning operations
and then filled with fresh yeast cultures from the laboratory for the next
cycle.
- vigorous, actively fermenting yeast - high and constant
beer quality
- no additional wort sterilisation - gain of essential
nutrients
- low equipment degree - minimisation of space and costs
- optimal aeration - reduced formation of foam
- circulation loop - optimal homogenisation, easy in-place
cleaning
- sterile air station with candle filter and product trap -
highest microbiological process safety
- in-line alcohol measurement - determination of the optimal
point of time for initiating further propagation steps