Surface energy investigation of chocolate adhesion to solid mould materials

Chocolate residues staying behind on the mould surface during chocolate bar manufacture are responsible for production losses, and increased processing costs due to equipment cleaning. This study investigates the determining role of surface energy in chocolate adhesion to the mould substrate and the ease of its demoulding. Four materials (quartz glass, stainless steel, polycarbonate, and Teflon) were investigated as mould substrates. A classical contact angle approach was used for the surface energy determination of mould materials. Chocolate-mould adhesion was measured by a simple separation test between the solidified chocolate and a mould probe using a Texture Analyser. The results demonstrated that surface energy of the mould material is a key determining factor of chocolate-mould interaction and has a significant influence on the adhesion of cocoa butter and dark chocolate to the mould. Further analysis has shown that the electron donor component of the surface energy is the main differentiating factor determining the extent of chocolate adhesion. It is concluded that a high surface energy material is generally not favourable for fabrication of the mould. For clean demoulding, the mould material should have a surface energy below 30 mN m −1 and an electron donor component of the surface energy of approximately 15 mN m−1.