In the current climate of Covid19 and national lockdown we at Muntons have been contacted by our partners in the brewing industry to support them with solutions to keep one of their most valuable employees alive. I’m of course speaking about every brewers’ house yeast, that needs to be fed with wort on a regular basis to ensure its vitality and cell count is always raring to go. In many breweries the management of the house yeast is a critical aspect of the business, with some breweries having reached generation numbers in the thousands.
Several of our customers have been forced by the current circumstances to stop production of wort and beer. This situation has led to some brewers having to come in on a weekly basis to brew short runs just to keep the yeast fed. We have investigated the suggestions made by brewers, engaging our own experts in the fields of brewing and liquid malt extract production and have found our brewing extracts to be highly suitable for growing yeast. We are currently looking into the best setups to enable optimal yeast growth with a minimum amount of staff and time spent on site.
A solution we are currently looking at is setting up a sterile FV next to a yeast management FV. The idea is to make a dilution of malt extract in water and boil it for 30minutes to ensure it is sterile. This solution could then be pumped into a sterilised FV via the heat exchange. The FV will need to be sealed to ensure no bacteria or wild yeast can enter. The temperature in this FV should be set to 5 -10C to keep the wort in good condition.
A few hundred litres of wort could then be transferred via a clean pump and pipework to a second FV. If possible, the transfer would go via the oxygenation line to up the O2 level in the wort. This would then be left at 18 – 23 C for a 2-3 days this depends on every brewers’ house yeast behaviour. You will know how long your lag phase is before fermentation kicks in and how long fermentations tend to take to start dropping. To be more scientific, you can measure the gravity of the fermenting wort and when it starts dropping you will want to go to the next step.
At this point we would suggest dropping the temperature to about 15C to slow down the yeast a bit and dropping out the fermenting wort until the yeast layer appears. Then after sanitising the equipment add more wort from the boiled wort tank into the yeast FV and give it another 2-3 days again you will know best how long your yeast will need.
When the boiled wort tank runs out you should have a large volume of viable yeast that you can pack into you preferred yeast storage containers. You will be able to rack the yeast from a racking valve after dropping the fermented wort out of the system, thus removing the potential dangers off top cropping. This also requires far less volume in the tank as you won’t need to fill the tank to the top.
Pack some of the yeast into your standard yeast storage containers and then as soon as you reach the maximum cold storage time you are comfortable with, repeat the process.
This process would enable a single person to keep the yeast going. It will also reduce the amount of time spent on site working alone and especially reduce the amount of time spent on ladders cropping yeast.
The entire process can be run on a small scale should you have the equipment. This would also remove the requirement of boiling the dilution as you could make a new one every time you need to add oxygenated wort to the yeast. We will continue looking into ways of supporting our partners throughout the brewing industry in these difficult times to keep breweries and team members going with technical brewing support and creative new ways of applying our knowledge.