Is it sufficient for a substance to change its essence for its color, taste, and smell to change, even if its chemical composition remains close to the original substance and it does not completely transform into another distinct entity, such as gelatin derived from a pig?

The decisive factor in "istihalah" (transformation) is the real change of the impure substance, such that it transforms into a different substance in name and description, and not merely a slight change in chemical composition. Vinegar, for instance, transforms from wine, and its use is permissible by consensus if it transforms naturally. However, if the wine is intentionally processed into vinegar or transported with the intention of transforming it, it does not become pure.