U.S. patent application 20180339833 (applicant Blueleaf Lab Oy, Espoo, Finland):
"An article for holding foodstuff. The article comprises a receptacle (4) having a wall with an inner surface for holding the foodstuff and an opposite outer surface. The wall is formed of a first material, such as a ceramic material, having a first thermal conductivity. The articles also has a shell (1; 5) spaced apart from the outer surface of the receptacle such as to define an interstitial chamber (2, 3) between the shell and the outer surface of the receptacle. The shell is at least partially formed of a ceramic material with a second thermal conductivity. Within the interstitial chamber, there is disposed a phase change material which abuts with at least the outer surface of the wall of the receptacle. The first thermal conductivity being greater than the second thermal conductivity, so as to allow for heat transfer through the wall to the phase change material, which will accumulate the heat."