New Cider brewer question re: headspace

[Dodgey]

Hello all!

I'm going to start a cider fermenting tomorrow, but I had a quick question. If I have a 5-gal carboy, is it okay to only brew 2 gallons in it at first, leaving a bunch of room in the top? I was thinking the CO2 would not allow anything in the top during primary fermentation, but I see people commenting on too much headspace possibly causing infection/badthings.

My plan is to just ferment in the carboy until the sugars are gone, then bottle, adding a little melted frozen concentrate to the mix right before bottling it, then letting it carb up for a bit using the soda-bottle-squeeze test, then pasteurizing on the stovetop to stop the in-the-bottle-carb-fermenting. I like my cider sparkling, and with just a little sweetness.

Thanks for your time!

 

[Chalkyt]

Primary turbulent fermentation is O.K. with the surface exposed to air, in fact it is considered desirable by people such as Claude Jolicoeur. I do my small batches of 5 litres (about 12-15 bottles) in a 10 litre unsealed container with just a cloth over the top . Once the turbulent phase settles, I then transfer to a carboy under air lock with very little head space for secondary fermentation. This lets me decide if I want to bottle and pasteurise at the right time or ferment right down, let it mature and add sugar or juice for carbonation.

I am setting up for heat pasteurisation of some of this year's cider right now (it is the end of Fall down here), so I have been doing a fair bit of research after a reasonably successful (only one bottle bomb) but rough and ready attempt last year. Beware, basic beer bottles are only good for 5 or 6 atmospheres so 2+ atmospheres of carbonation heated up to more than twice room temperature starts getting you close to this danger territory. Stronger bottles give you much more margin for error.

For stove top pasteurisation information, look at the sticky at the top of the forum, then one of many posts from JimRausch re his simple Cooler Pasteurization method (search JimRausch's 16April 2018 reply to a post for the short version). Also, a more "scientific" approach is covered in a post by Bembel 11 May 2016. Both these methods use low temperatures to minimise the chance of bottle bombs.

 

[Dodgey]

Thanks much for your reply! I am worried about the bottles, but I'm not going to let them carbonate too strong, probably less than how soda feels in the plastic bottles. At some point I probably will purchase a set of bottles specifically for this, instead of clean/sanitize beer bottles. As for pasturizing, I was going to follow this How to Pasteurize Your Bottles for Sweet Carbonated Cider - a BrewUnited blog entry .

 

[Chalkyt]

Yep, that process should work well... it is very similar to JimRausch's Cooler Pasteurization method.

My experience is that limiting the bottle temperature is crucial... I didn't, and the bath temperature got too hot, so did the bottles and hence their internal pressure, and one went kaboom. If you are fluffing around putting bottles in, checking the water temperature and taking them out, it is easy for the time taken and temperature to run away on you. Hence this time around I am using a cheap sous vide cooking wand from eBay to control the water bath temperature and a bottle of water that goes in the bath with the cider bottles with a digital cooking thermometer in it.

If you look at Bembel's post you can actually do your proposed method at a lower temperature for a longer time and thus a bigger margin of safety (and also understand why you are doing it... you need to generate a certain amount of "pasteurisation units" which result basically from temperature x time). Jolicoeur suggests 149 degrees for 10 minutes, which seems to be the current "wisdom" as this should keep the heated bottle pressure below 5 atmospheres. As with a lot of cider stuff, low and slow seems to be the way to go.