Red Star Platinum Yeast contains dough improvers along with yeast.
Ingredients: Yeast, Xanthan Gum, Ascorbic Acid, Sorbitan Monostearate, Enzymes
One can buy dough improvers in bulk. Here are two available from
Amazon (USA) with varying user reviews.
https://www.amazon.com/Professional-Dough-Improver-1lb-Bag/dp/B00BF0E7CQ
Professional Dough Improver
Use 0.5% to 2% of flour weight (1 lb bag treats 50 to 200 lb flour)
$14.10 USD for 1 lb
https://www.amazon.com/Scratch-Premium-Dough-Conditioner-Improver/dp/B08NWBWMHB
Scratch Premium Dough Conditioner
Use 1 tsp to 1 cup flour (this is about 2%)
$12.95 USD for 10 oz
If you use 1% conditioner, this is less than $0.15 per pound of
flour, which is probably a lot cheaper than what Red Star adds to the
price of the yeast.
We haven't experimented with either of these nor with the platinum
yeast (looked but couldn't find it in our stores).
Have fun,
Jeff & Reggie