Tunnel pasteurization of fruited sours

[Chris-DK]

Hey everyone

So I am going to be moving to a new brewery where I'll have access to a tunnel pasturizer. We will primarilly only be using it for non-alcoholic contract brews, but also when we once in a while make fruited sours.

A lot of these fruited sours are not going to be refermented before packaging, so we are going to pasturize them to prevent refermentation.

Do any of you have reccomendations regarding PU numbers we should be aming for? And should we be going to higher PU's the higher the fruit content is, or should it remain mostly the same for all fruited sours?

Thanks!

[dick murton]

Firstly, apologies for not giving a straight answer, but perhaps a little food for thought.

I have to ask why you feel it is necessary to pasteurise, as there are plenty of non pasteurised smallpack products that contain yeasts and bacteria such as Kombucha, kefir (and I am thinking of water Kefir - but to be honest, I am not sure how much difference there is between this and Kombucha - probably just the lack of tea) and bottle conditioned beers.

Unless you are filtering to be almost as bright as most keg and bottle beers, which it appears you are not, then you are likely to have to use very high numbers of PUs, which may well cause significant flavour changes.

Typically, bright filtered beer is subjected to 15 to 25 PUs - circa 60 degrees 20 minutes in the pasteurisation zone. Once you go above this, particularly if total in package oxygen (TPO) is not extremely low, then significant flavour changes / hazes are likely to develop during pasteurisation and during the shelf life. Based on bright filtered beer typically having a spec of < 100 ppb, I would expect you to need significantly less than this, best guess < 25 ppb (happy for someone to correct / advise otherwise).

A major cider producer subjected their bright filtered products to hundreds of PUs, but there is virtually no protein in cider to cause hazes and some of the off flavours, and of course, virtually no yeast or bacteria pr-pasteurisation. I believe since I worked there, they have dropped the PUs down to around 25.

Carson City Health & Human Services state in one of their on-line documents - Pasteurization or other treatment method [of fruit juice] must be validated to achieve at least a 5-log pathogen reduction. https://gethealthycarsoncity.org/wp-...P-Guidance.pdf

Tetra-Pak state in the paper - https://www.tetrapak.com/content/dam...eurization.pdf

"To avoid pathogenic bacteria in the juice it is important to always pasteurize the juice at a process that is no less than 72°C for 15 seconds.
One batch of 4,000 litres of orange juice (11.3ºBrix, pH 4.0) was pasteurized at 78°C/22 s, (approx. 140 PU based on beer) which corresponds to a heat treatment at 80°C/9.5 s, (approx. 120 PU based on beer) i.e. a lower heat treatment than 80°C/15 seconds (approx. 180 PU based on beer). The result confirms the findings from the in-house test that 80ºC for 15 seconds gives enough heat load in the second pasteurization to produce a commercially sterile product." Note that I have inserted the PU figures in brackets based on a beer based PU calculator - so I have no explanation for the differences when Tetra-Pak appear to say they are equivalent.

Also, this link https://www.tetrapak.com/en-gb/solut...e-fruit-drinks

"The first pasteurization is usually at 95-98°C for 10-30 seconds, killing microorganisms and deactivating pectin methyl esterase (PME), the enzyme that causes cloud loss or gelation. The second time is to destroy any microorganisms that may have contaminated the juice after the first pasteurization, during reconstitution from concentrate or that have survived storage. This is normally done at 95°C for 15 seconds (27,300 PUs using the same calculator as above!!) for fruit juices with a pH below 4.2. When aseptically packaged, the juice can be stored under ambient conditions."

Not sure if this helps at all, but look up the Tetra-Pak documents.

[Chris-DK]

Yeah, I think we are talking about something completely different.

I am talking about heavily fruited sours, that are not refermented, so in order to prevent refermentation in the cans, and thus can bombs, we need to pasteurize them.

This is not kombucha, cider or highly filtered marco lager.
I am well aware of the theory of pasteurization and the flavor impact of that, but that doesn't really apply to beers like the ones I am talking about.

But perhaps this was the wrong place to ask this question.

[dick murton]

"heavily fruited sours" - that's why I thought the info on fruit juice pasteurisation might help.

Sorry it didn't answer exactly what you were looking for. The only other thing I can suggest is to small batch (hand) pasteurise a number of bottles with say 50 PU, plate out, and repeat with higher or lower PUs until you are happy the required shelf life can be achieved. I realise hand batch pasteurisation is not likely to be as accurately controlled as your tunnel passie, but it's a start.

[Fredi]

Also, if you include fruit into your beer before pasteurizing, it is important to watch for the size.
of the fruit, as this can reflect the heat and hinters pasteurization.

Cheers

[Fredi]

Also, be careful with pasteurizing the product that has fruit pieces.
The larger the fruit, the more heat is reflected and maybe you get problems.

Thanks
Fred