7 C.F.R. § 58.344 – Storage of finished product in freezer.

(a) Sharp freezers. Plastic cream or frozen cream intended for storage shall be placed in quick freezer rooms immediately after packaging, for rapid and complete freezing within 24 hours. The packages shall be piled or spaced in such a manner that air can freely circulate between and around the packages. The rooms shall be maintained at −10 °F. or lower and shall be equipped to provide sufficient high velocity, air circulation for rapid freezing. After the products have been completely frozen, they may be transferred to a freezer storage room for continued storage.
(b) Freezer storage. The room shall be maintained at a temperature of 0 °F. or lower. Adequate air circulation is desirable.
Butter intended to be held more than 30 days shall be placed in a freezer room as soon as possible after packaging. If not frozen before being placed in the freezer, the packages shall be spaced in such a manner as to permit rapid freezing and repiled, if necessary, at a later time.