Is there any chance in contaminating items on the hot side based off of a plastic bucket I use for grains and spent grains? I’m basing this off of the fact you can sour beers with grains at a certain temp.
Yes and no. As long as you’re not letting your wort sit in the 100-120F temp range for too long, you’ll be fine. Lacto is slow at cold temps and killed off at higher temps. That’s why for sour-wort beer you need to re-inocculate your wort after the mash. Mash temps for long enough aren’t going to leave you with much viable lactobacillus.
I agree with Eric Bana. I often use old plastic for transfer and chilling of hot wort prior to pitching and transfer to glass carboys. I haven’t had issues with using plastic for this short time (typically less than 12 hours).
However, I have had problems with plastic for longer periods of weeks & months. Don’t keep it there for a very long time IMHO.
Unless you are sanitizing your pre-boil equipment then it is already infected with bacteria and wild yeast. All that stuff is naturally present. You don’t need to have grain present for them to show up. The boil kills it all off so it’s not a sanitation problem on the cold side.