21 CFR 101.4©
"When water is added to reconstitute, completely or partially, an ingredient permitted by paragraph (b) of this section to be declared by a class name, the position of the ingredient class name in the ingredient statement shall be determined by the weight of the unreconstituted ingredient plus the weight of the quantity of water added to reconstitute that ingredient, up to the amount of water needed to reconstitute the ingredient to single strength. Any water added in excess of the amount of water needed to reconstitute the ingredient to single strength shall be declared as “water” in the ingredient statement."
or possibly 21CFR101.100 (ii) (a)
"The following foods are exempt from compliance with the requirements of section 403(i)(2) of the act (requiring a declaration on the label of the common or usual name of each ingredient when the food is fabricated from two or more ingredients)
...
Processing aids, which are as follows:
(a ) Substances that are added to a food during the processing of such food but are removed in some manner from the food before it is packaged in its finished form."