Flat lager can i reuse??

[silkyuk9]

Ok, i have 50 pints of Youngs lager in my barrel, the problem was a leeking pressure valve. anyway, the lager is clear but flat. at the moment i only have a basic plastic screw top that i got with the barrel now on the barrel, until i get a new cap with valve.

i cannot inject any co2.

is there anything i can do with the lager rather than throw it away.

is it possible to add a sache of brewing yeast and another kg of sugar and heat up again to a fermentation temperature?

i do not want to throw away if i can salvage.

any suggestions, i do not want to drink it flat.

[silkyuk9]

thanks