Why Do Some Say 24 Hours Before Yeast?

First of all, hello NB’ers! I have read much on this forum, but this is my first post. I have made several 6 gal batches of wine using Welch’s fruit juice, mostly about 2 years ago. I have enjoyed the experiences, and produced wine that I was very happy with. My knowledge comes from you folks, the local wine shops, YouTube, the friend who got me started, and a book I bought called “Mary’s Recipes” by Jerry Uthemann. I have found a discrepancy about when to add the yeast that has me a bit confused. For example, “Mary’s Recipes” says to:

  1. pour juice in the primary fermentor
  2. add water
  3. add sugar
  4. add any other additives, including campden tablets, but not yeast.
  5. set SG at 1.095, then cover with sterile sheet for 24hrs.
  6. THEN add yeast.
    etc, etc…
    I was hoping you more experienced folks could share your opinions and experiences about the 24 hour thing. Is this 24 hour thing even required? Is it so all the stirred up ingredients have time to completely dissolve and break down into finer particles?
    Thanks NB for this forum, and thank you folks for any help!

I forgot that it could be time for the SMS to kill any wild yeasts in the must before the wine yeast is added…

Yes you need to wait after adding campden tablets before pitching the yeast or the yeast will be severely hindered.

This is the reason. You add the campden tablets to knock out any wild yeast or bacteria that might be present, but as soon as you add it, it starts to bind with oxygen and otherwise break down and loose it’s effectiveness. By 24 hours in, it has lost enough of it’s effectiveness to allow cultured yeast (which is more resistant to sulfites than wild yeast) to colonize the must without serious impact from it.