Is it yeast contamination?(during kettle souring)

[Kimchi]

Hi! I'm homebrewer from korea.
I did some kettle souring by yogurt.but there is some problem.
SG was 1.053 and pH 4.5 before souring.
After souring 1 week, pH was 3.6 and boil 45min. And I measured gravity of wort. IT WAS 1.016!!! It was my second kettle souring batch.
I think there were some yeast contamination during kettle souring. Actually when I tasted soured wort(after souring), there are no co2. But lots of foam in boiling..dumped.
What do you think about this?

 

[RPh_Guy]

I think there were some yeast contamination during kettle souring.

Yes, definitely.

I recommend finding a source of Lactobacillus plantarum so you can use a modern souring method:
https://www.homebrewtalk.com/forum/threads/fast-souring-modern-methods.670176/

Welcome to HBT!