The Yeast Sediment In My Starter Changed Colour

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Hi,

I made a pacman starter from a bottle of track and field about a week and a half ago. It started slowly and settled ready for pitching. I needed to stretch it as I was planning a rogue brutal knock off and on advice I needed as much yeast as I could get.

With the starter still plodding along with a second addition of 1040SG wort and sat my still hot cube nearby(Say 400mm). I noticed the temp change increased fermentation but I thought this would be a good thing having it nice and lively a day or so before I pitch.

I went to pitch it over my cube and noticed two distinct layers of sediment.

I am not going to use the starter as I am pretty sure it's contaminated.

The partially fermented wort has a slight vinegar note and taste so I am pretty sure it,s Acetobacter.

Any body have an idea why the change in sediment colour.

Is it the temp change or the acetobacter that has changed the sediment colour.

See pic attached.

 

[MaltyHops]

...
I went to pitch it over my cube and noticed two distinct layers of sediment.
I am not going to use the starter as I am pretty sure it's contaminated.
The partially fermented wort has a slight vinegar note and taste so I am pretty sure
it,s Acetobacter.
...

I think the starter might be ok - could just be trub from the double starter wort
used. Starters often have a very sour acidic (like lemon juice) taste to them
since there's not much in the wort except malt so don't taste that nice.

Assuming you haven't pitched the cubed wort and you're going to make another
starter, it might be worth making a mini-batch (say 2 - 3L in a cleaned, sanitised
cordial bottle or something with glad wrap over spout) with the first starter using
some malt or kit goo to have a further check whether it's definitely off or ok.

If it tastes fine, cool it down, let the yeast /trub settle and pout off the beer. Then
the yeast can be combined with your second starter (if you make it) for a big starter.

T.