Thursday 16 July 2020

Fruity folly and pasteurisation perils

Another brewery has come a cropper with cans of their fruit beer exploding. This time though a novel approach to the problem has been taken as they say they "are obsessive in our focus on quality" and it's up to the customer to keep their beer in a fridge if they don't want it to explode!
They also waffle on about their robust laboratory programme and expensive equipment, despite the fact it has obviously failed.

Of what they mention it appears they're actually relying on flash pasteurisation (i.e. heating the beer rapidly for a short period of time in a plate heat exchanger and holding tube) to prevent microorganisms growing in their beer. Beer, already having been fermented, is quite a hostile environment to most microorganisms and only requires a low level of pasteurisation to become microbially stable. Since the work Del Vecchio in the 1950s the amount of pasteurisation a product has is measured in Pasteurisation Units (PU). I won't go into the details about PUs here but the higher the number the higher the degree of pasteurisation and the more heat and/or time needed to achieve it.

The level required to might be 15 PUs (or sometimes even less). As the table below shows fruit juice requires considerably more:

Twenty times more in fact! Hardly surprising that beers with a large amount of added fruit continue to have problems with fermenting in the can. If you're going to include new ingredients in your beer you may need to change your processes too if you want to avoid problems.

Tuesday 14 July 2020

First the Whorst

The current plague situation has definitely caused in upsurge in internet beer nerdery. Reports have come in that ex-beer blogger Whorst has been sighted on a home brew forum. Back in the days of coal fired computers, when people still paid attention to blogs, he very active in the blogosphere. Though he had it in for the Tand for some reason. At this rate it seems I'm going to have to pull my finger out and do more blogging myself.