Tell me about using plastic bottles to gauge carbonation

I have a couple of gallons of cider that I'm getting ready to backsweeten with tart cherry juice. I know that bottle bombs are a concern when backsweetening so I want to do everything I can to avoid that.

It was originally recommended that I try a bottle a day to check the carbonation and then cold crash or pasteurize. Since it's only a couple of gallons it seems that I might run out of the cider before it is ready.

So somewhere I read about people using plastic bottles as a gauge for carbonation. How do I do it, and what am I looking for?

Thanks!

Bump.

Was hoping to get some feedback on this method as I need to bottle this weekend to get them out of the spare bathroom for company next week.

Thanks for any advice!

Sure, I do this with every batch. Works great.

Get some small plastic soda bottles, I find plain seltzer is best because you don't have to worry about weird flavors sticking around. Just make sure it's a bottle in good condition that held a pressurized beverage before. You can also buy new brown PET bottles, but if you're just doing 1-2 per batch I don't see the point. Sanitize, fill as normal, squeeze the remaining air out of the bottle and screw the cap on rather tightly.

It'll start off all squishy and flaccid, as it carbs up you'll see a headspace again and the bottle will be firm.

If it's beer, make sure you keep it out of the light (putting it in a small paper bag works well).

I think they fill a Soda Bottle, and then wait until it gets about as firm as an unopened soda. Thus there will be about the same pressure in your now carbonated cider as the soda. Then you would pasteurize, kill off the yeast and enjoy your cider. (don't use a water bottle, they are too weak.)

It was originally recommended that I try a bottle a day to check the carbonation and then cold crash or pasteurize.

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Cold crash is generally done in the carboy, before carbonation, it puts the yeast to sleep and they hopefully settle on the bottom of the carboy, then you siphon the cider off the little bit of yeast.

Pasteurization is done in the bottle, generally with a hot water bath, and after carbonation if you want sparkling cider, before carbonation if you want still cider.

Hope that helps!

Thanks for the input guys. Exactly what I needed.

Should I expect the plastic bottle to return to regular size? I'm using a 12 oz plastic Sprite bottle. So far the head space has increased by about a half inch.

I'd go by feel. If it feels like a warm soda bottle (pretty stiff, and "regular" size) it's probably carbonated like soda.

Below is a pic of our progress so far. We bottled on Sunday evening. Added our cider and squeezed air out until the liquid was about at the base of the cap. The bottle is still a little squishy, but quite a bit of headpiece has formed. If you can see the lines on the right side of the bottle the second from the bottom was drawn this morning.

Are we on the right track? Any guesses to how much longer until we need to pasteurize?

Wow....just checked on the bottle again and it is now back to regular shape with another quarter inch or so of head space. The bottle still has a little give to it so I guess we'll let it go a little longer. I can't believe how fast this is happening. Should it happen this fast?

Every batch I brew includes a Pepsi bottle or two. I do not squeeze out the air first, as this might (I say might) not give me a true read or feel as to the actual pressure being built up. This is for BEER not cider but it gives me a good idea how carbonation and brightening is getting along. I also open the plastic bottles a few weeks into conditioning for a taste test.

bosco

So the Sprite bottle was pretty firm yesterday and we got a little concerned so we opened it up for a sample. There was a very faint 'pfffft' sound when I opened it and there is a slight tingle on the tongue when tasting, but not too much going on in the way of bubbles. Guess we jumped the gun quite a bit but we are a little nervous about going too long.

How long does this process take with a cider? Same as beer?

I am somewhat using you as my guide on this one. I bottled my first ever batch of cider on the 16th. I also did a back sweet for bottle carbing. I made sure I siphoned a very small amount of yeast into my bottling bucket. However, I did not pour a test plastic bottle. I am going to check my first bottle tomorrow after 6 days at room temp 71. I did one swingtop 1ltr bottle, 2 - 22's and 6 12's.

Depends on temp, SG, etc. Mine took a few months to carb, but it was also 10% abv.

The squeezing the air out bit seems very counter productive. First there is a big variable in how much air you leave before you squeeze it out. Secondly, all the carbonation that is produced will not dissolve into the beer/cider, but will fill up the extra space. Did you squeeze the air out of your glass bottles? Then why do it to a bottle you want to use to test progress in those bottles?

An issue I had last time I did this was that if you fill the bottle completely and use the bottling wand to create the 'proper' amount of headspace, you actually don't get as much headspace as in a normal soda bottle, so that the plastic bottle got hard before the glass bottles were actually carbonated. Next time I will try to match the level of headspace with an unopened soda bottle of the same shape.

sorry to bump an old thread but its got a lot of useful information. So if I want a carbonation like a regular 7up bottle, Id fill the cider to the same level the 7up was at originally, then to the best of my ability try and match the firmness of my plastic sample to a regular factory sealed 7up bottle at matching temperatures?

Something like that. Note that sodas are (I'm almost positive) more carbonated than ales and ciders.

thanks tennesseen, ill play it safe and wont wait till its too carb'd. i dont mind a lightly sparkling cider. after pasturization, will the taste still improve over time?

Yes. I had a bad cider i sweetened and pasteurized. It was still bad. A year later it was much better.