Yeast Hulls are usually the first action when you have a stuck or sluggish alcoholic or malolactic fermentation. Yeast Hulls are essentially dead yeast cells that absorb auto toxic yeast by-products that could be inhibiting your active yeast or ML culture from doing their job – finishing your fermentation! Yeast Hulls are then typically followed by Pro-Desert in the case of a stuck alcoholic fermentation or Acti Ml in the case of a stuck ML ferment.