Killing yeast in keg? CO2 or not?

[parrothead600]

While ageing my cider in a carboy, I saw a very thin transparent white film on top of the cider. It broke apart & sank at the slightest disturbance. Fearing the beginning of a lacto-infection, I drew a sample & tasted it. It tasted fine & I haven't died yet, so I assume that it is OK.
After further research on the subject of lacto-infections, I learned that I need to eliminate most of the headspace in the secondary, which I didn't do. I decided to rack the cider to a clean vessel & hit it with campden & potassium sorbate. The only clean vessel that was available was a keg. I am planning on backsweetening this batch & leaving it in the keg anyway.
My question is: will it be OK to hit this with the CO2 while the campden & potassium sorbate do their thing? Or will the CO2 have a negative effect on the process?

 

[Maylar]

That sounds like a plan to me. If you purge the air from the keg as though you were going to carbonate it you'll replace O2 with CO2 and whatever was growing in your cider won't be able to continue.

CO2 will have no effect on the stabilizing. The only issue I see is whether the yeast had sufficiently dropped out of solution before adding the sorbate. I think I'd wait for it to age in the keg without back sweetening and check for sediment when you get to that point.

 

[parrothead600]

I'll do that. Thanks for the info.