Utah State University Extension
This fact sheet describes pretreatments that can be used to prevent darkening of fruits prior to canning or dehydrating, including ascorbic acid, citric acid powder, lemon juice, citric acid mixtures, fruit juice, and sulfites.
Washburn, Carolyn and Jensen, Christie, "Pretreatments to Prevent Darkening of Fruits Prior to Canning or Dehydrating" (2017). All Current Publications. Paper 1763.