White film on grain starter, should i dump it?

[Metalhead_brewer]

Hi guys, first time doing sours and i'm about brew a kettle sour and use grain starter to sour it, 3 days and it looks like this, the grain smells really nice, sweet, grainy with little notes of sour like rice wine smell is it good? Or should i dump it?

 

[RPh_Guy]

The film is called a pellicle and it's completely expected in this case. You can use it.
https://***************.com/wiki/Pellicle
However, kettle souring with grain might not be the best idea.
See here:
https://***************.com/wiki/Kettle_souringAnd here:
https://***************.com/wiki/Sour_beer

 

[Metalhead_brewer]

thank's for the links now i know about modern sour methods i'll implement in future batches, i proceeded with grain souring because i wanted to experiment with, but didn't know about the good, the bad and the ugly of doing it, i did 1 pound of grain starter and soured 15 gallon to 3.4ph in about 18 hours with maintained temperature of 38-42 celsius and as expected i got pellicle in kettle as well, smelled reallly nice, some kind of bready creamy bittersweetness O.G. was exactly what i expected the only thing that intrigues me is that wort tasted a little bit like vinegar but i read that is caused by Acetobacter but this will go off with malolactic fermentation, i pitched a top cropped k-97 yeast that i collected 3 hours before and it began bubbling as hell in about 6 hours anyway lets see how this turns out, here are some pictures of the brew kettle before boiling.

 

[day_trippr]

I love science! It can be so funky!

Cheers!

 

[RPh_Guy]

You didn't boil it after souring?

Beer does not undergo malolactic fermentation because there is no malic acid.

 

[Metalhead_brewer]

You didn't boil it after souring?

Beer does not undergo malolactic fermentation because there is no malic acid.

yeah i boiled for 60 minutes and threw some 1 year low AA aged hops

 

[RPh_Guy]

Boiling would have killed everything from the souring phase. The pellicle indicates some wild microbes got into the wort/beer after that point.

 

[Metalhead_brewer]

the pellicle from the pictures are from the boil kettle in the souring phase, before that i boiled it, and by now is happily fermenting with the k-97 yeast with any issue it looks like any "normal" ale and smell from airlock is really nice.