Organic Materials Review Institute for the USDA National Organic Program. 1. Pretreatments to make the uncooked materials ready amino acids supplier for supplements the principle extraction step and to take away impurities that may have unfavorable results on physicochemical properties of the final gelatin product. Acid treatment is especially appropriate for less absolutely cross-linked materials similar to pig pores and skin collagen and normally requires 10 to forty eight hours.