Proteinase A

[Roger Greene]

Odd question, I searched the internet for an answer but couldn't find it. Does anyone know the inactivation temperature for Proteinase A?

[Natrat]

According to Springer's it's 95 deg, with maximum activity between 50 and 60. Acid denature occurs at ph 6.0 and is irreversable.

Hope that helps.

[Roger Greene]

that's celsius right?

[Natrat]

Yup...deg C. Sorry...I assume everyone uses C, and that often gets me into trouble.

Just curious as to why you want to know? It took me a few minutes to find it...

[Roger Greene]

Well I was just curious if pasteurization (flash or tunnel) would have any effect on the activity of Proteinase A in the packaged beer.

[Jaltwies]

What is the dwell time? I have a PkA chart I can look at

[Ipscman]

From 2010 edition of Kunze, Technology Brewing & Malting:

p. 515, "To achieve microbiological safety, recovered yeast has to be flash pasteurized with 40 to 100 PU, which also stops the proteinase A activity."

p. 507 "...the yeast excretes a proteinase A, which leads to a considerable deterioration of the foam due to the breakdown of foam positive substances in the beer. This is of particular importance for beers where no heat treatment occurs before filling and where proteinase A passes into the finished beer.'

Hope this helps.
Mark
http://www.hiddenwellbrewery.com

[dick murton]

That was a timely extract from Kunze.

I have been looking at a recovered beer pasteuriser for different reasons, and now I know we have another reason for not dropping too low - not that I would have expected to get down to normal sales beer PUs without micro issues anyway due to the loading pre-pasteuriser.

Thanks