Phew, one of the liveliest threads for a long time.
Going back to David Quinns query. Lots of breweries filter their beer, and then flash pasteurise, between the bright beer tank and keg filler, or indeed between bright beer tank and bottle if aseptically filling. Sizes vary from a couple of hundred hectolitres to tens of thousands of hectolitres per week. Alternatively you can sterile filter and then fill asptically, again, into keg or bottle.
Personally I think any form of filtration changes the character of the beer considerably, and I suspect not many would disagree. The problem with non sterile filtration (as state - 0.4 micron absolute) is that you are always going to get some yeast and bacteria passing through, which can grow up sufficiently to cause hazes and or off flavours.
The problems with pasteurisation include difficulty in accurately controlling the flow rate and temperatures to give accurate numbers of PUs (pasteurisation units) and difficulties keeping the gas insolution at high temperatures. Micro bubbles of CO2 are liable to form round yeast and bacteria which helps protect them against the effects of the heat. Finally of course, there are the flavour changes generated by heat, even during flash pasteurisation, especially in presence of oxygen. As always, the higher the oxygen level, the more noticeable the flavour changes are likely to be.
Finally, most breweries in the UK use in line heat exchanger, typically of the ice pack type at point of dispense, sometimes with the cooling lines extending into the font. Cellars for the kegs, should be cool, but often are not - regularly reccommended temperature being 55 deg F.
Cheers
Going back to David Quinns query. Lots of breweries filter their beer, and then flash pasteurise, between the bright beer tank and keg filler, or indeed between bright beer tank and bottle if aseptically filling. Sizes vary from a couple of hundred hectolitres to tens of thousands of hectolitres per week. Alternatively you can sterile filter and then fill asptically, again, into keg or bottle.
Personally I think any form of filtration changes the character of the beer considerably, and I suspect not many would disagree. The problem with non sterile filtration (as state - 0.4 micron absolute) is that you are always going to get some yeast and bacteria passing through, which can grow up sufficiently to cause hazes and or off flavours.
The problems with pasteurisation include difficulty in accurately controlling the flow rate and temperatures to give accurate numbers of PUs (pasteurisation units) and difficulties keeping the gas insolution at high temperatures. Micro bubbles of CO2 are liable to form round yeast and bacteria which helps protect them against the effects of the heat. Finally of course, there are the flavour changes generated by heat, even during flash pasteurisation, especially in presence of oxygen. As always, the higher the oxygen level, the more noticeable the flavour changes are likely to be.
Finally, most breweries in the UK use in line heat exchanger, typically of the ice pack type at point of dispense, sometimes with the cooling lines extending into the font. Cellars for the kegs, should be cool, but often are not - regularly reccommended temperature being 55 deg F.
Cheers
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