Minimising headspace

[Appelwoi]

I've read that minimising headspace is good because it minimises oxidisation, and I assume this applies to cider, not just beer. But I have several practical questions about headspace which aren't answered in the threads I consulted.

1. I'm brewing cider in a 24 litre bin and three 4.5 litre demijohns. I intend to leave the brews in their original containers (ie, I won't be using a secondary). Given that the gas above the liquid should be mostly CO2 by now, am I right in thinking that I don't have to worry about reducing headspace?

2. If that's wrong, or if my plans change, how much (or how little) headspace should I aim to finish up with? An inch? More? Less? Or should I not worry about an absolute measure of headspace, and just keep it to a minimum when selecting vessels and measuring quantities at the outset?

3. How would I reduce headspace in practice? Would I add distilled water, or could I use shop-bought AJ (without preservatives)? After the initial burst of activity, topping up the demijohns with AJ (leaving barely any headspace) seems like a reasonable idea.

 

[rrrk]

glass marbles sterilized, buy them cheap at the dollar store and add them to your primary

 

[bmd2k1]

...I'm a hard cider newbie...but from what I've read so far....headspace in the primary isn't an issue....it's in the secondary where it should be minimized. Any experts...please correct me if I'm wrong [emoji12]

 

[bernardsmith]

Yeah, there is no issue of headspace in the primary because during active fermentation the yeast are producing a whole passel of CO2 (half the weight of the sugar is the WEIGHT of the CO2) and that CO2 is exerting real pressure preventing air (O2) from creating any problems. However, after active fermentation has ceased the air will exert about the same amount of pressure as the CO2 and after a fairly short time half the headroom will be filled with air and half with CO2. Bottom line - you really do want to make sure that there is not much more than say 1 cubic inch (or less ) of headroom after active fermentation has ceased which is why most seasoned wine makers transfer (rack) their wines, meads and ciders from a loosely covered buckets with large mouths to carboys with narrow necks sealed with bungs and airlocks. The idea is that the bucket is filled with MORE must than the secondary (the carboy) can hold - so there is rarely any need to buy marbles or dilute your ciders or wines with water or even add additional similar wines or ciders to take up more room. In other words, you plan to make 5.5 gallons when you want to bottle 5 gallons. If your planning was otherwise I would look for smaller secondaries to minimize the headroom. Oxygen at this point is not your cider's friend.

 

[Maylar]

Right up to the necks...

And if you need some filler, glass stones from a crafts store (vase fillers) -

 

[Appelwoi]

Thank you all for your comments. The idea of using inert objects like marbles never occurred to me. So simple... I'll give it a try

Mylar - nice pics! I hope my first results will end up as clear as yours. Right now they are totally opaque. But I couldn't figure out the purpose of the wooden(?) structure in the first pic - can you enlighten me?

Yeah, there is no issue of headspace in the primary because during active fermentation the yeast are producing a whole passel of CO2 [which] is exerting real pressure preventing air (O2) from creating any problems. However, after active fermentation has ceased the air will exert about the same amount of pressure as the CO2 and after a fairly short time half the headroom will be filled with air and half with CO2. Bottom line - you really do want to make sure that there is not much more than say 1 cubic inch (or less) of headroom after active fermentation has ceased

Thanks for explaining it, and for the advice on how to plan future batches. However, on this occasion I'm not planning to transfer from a primary to a secondary prior to racking, partly because this batch has used all my vessels, so I have nowhere to transfer the liquid to. Hence my musings about whether to top up with AJ once the rapid fermentation phase is over. In the future I will aim to brew a smaller volume in the bin as primary, then transfer the liquid to my demijohns as secondaries.

 

[bernardsmith]

I think it should be the other way: Your primary should have more than a gallon (or more than 3 or 5 or 6 gallons) so that you can rack a gallon and fill the secondary. Any excess you can add to a mason jar and store in your fridge...

Can't speak for Maylar, but the wooden crate helps transport a carboy (carrying a full carboy (5 gallons weighs more than 40 lbs) by the neck is a recipe for disaster and glass can be very slippery when wet, although Maylar's is plastic). A crate also prevents the bottom (when glass) from striking a concrete or other hard surface. It also means that the bottom is held away from very cold surfaces. I routinely use plastic milk crates and their clones for anything larger than 1 gallon...

 

[Maylar]

That's a 3 gallon Better Bottle PET carboy in my picture. It's rather ungainly to handle as being plastic you can squeeze it and overwhelm the airlock, and it's also slippery. So being a woodworker I fabricated a custom made carrier for it. It also serves to support the jug upside down when draining it.

 

[MarkKF]

I have 6-1/2 gal. Buckets and 6 gal. Carboys for primary & 5 gal. Carboys for secondary. I start 5-1/2 gal. and freeze 1/2 gal. for backsweetening.