The unsteady mass transfer of the packaging constituents to a food has been analysed. The diffusion coefficient inside the packaging was considered concentration - variable while the food was considered concentration spatially gradientless. A well-known technique (Kirchhoff transformation) was used to solve the non-linear mass balance equation. https://www.spidertattooz.com/Horse-Painting-3-Piece-HD-Multi-Panel-Canvas-Wall-Art-Frame/