A breast milk storage system which comprises a mandrel for selective engagement with a bottle connector of a breast pump. The storage system also includes at least one clamp in pivotal engagement with the mandrel, and a lock ring. The lock ring is positioned for rotation about the mandrel and the at least one clamp. Rotation of the lock ring effectuates pivoting of the at least one clamp between an open position and a closed position. In the closed position, the at least one clamp is pivoted with respect to the mandrel and presses against the mandrel so as to retain a storage bag in place by pinching said storage bag between the at least one clamp and the mandrel.