Acetaldehyde in my yeast starter

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Jan 26, 2021
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Made a 2l yeast starter with wyeast 1968 but wasn't able to brew the day I had planned so i let of set at room temp for 48hrs the capped it and put in the fridge. Planned on brewing today so i pulled it out and poured of some of the liquid and gave it a smell and taste and it's straight green apple cidery. So my question is if i make another yeast starter using the same yeast will it clean up the acetaldehyde or should I just pour out and use something else?
Yes, it will clean it up. However, since acetaldehyde is an intermediate product of fermentation, it will be converted into ethanol during your main fermentation.
I'll have to go back and read, but acetaldehyde is one of the byproducts of yeast when they are just getting to their best state for turning sugar in to alcohol and CO2.

So think of it as a good thing for the brief time it's going to be in what will eventually be the finished product.
My plan is to pour off all the liquid and make another 2l starter with the built up yeast cake. I think the fault was that i didn't add any yeast nutrient thinking that because the wyeast package is supposed to contain those anyways. Am going to brew a west coast IPA and really wanted to use the wyeast 1968 strain but don't want to ruin a whole batch, my other yeast option are dried k-97 or 34/70
If you're not using a stir plate, or some other form of agitation, such as the s-n-s method, acetaldehyde can build up somewhat. It's not going to harm your beer if you pitch it like that. As was mentioned before, it will be converted to alcohol.

Are you using a yeast pitch/growth calculator such as this one? If not, I can recommend it as well as a stir plate. It saves money as you can propagate more yeast and faster.
No i don't have a stir plate i usually just shake it several times thorough the day and no i haven't used a pitching calculator before i just make a 2l starter and assume it's good...i know it's not the best method just the easiest