Effect of Cocoa Solid Contents on Sorption Isotherms of Dark Chocolates
Gülten ŞEKEROĞLU and Ahmet KAYA
University of Gaziantep, Engineering Faculty, Food Engineering Department,
Gaziantep - TURKEY

The sorption isotherm represents the relationship between the water content of a product and the relative humidity of the equilibrium ambient air at a specific temperature. It is also a graphical presentation of the sorption behavior of a product.
It is known that chocolate products have different amount of cocoa solids and different products are often associated with a specific cocoa solids content changing from bitter to sweet. Therefore, the aim of this study was to investigate the sorption behavior of dark chocolates containing different cocoa solid contents by a new approach using dynamic vapor sorption (DVS) method. The moisture sorption isotherms of three different dark chocolates having 99, 70 and 50 % cocoa solid contents were determined at 20, 30 and 40°C over a relative humidity range of 0 to 90 %. Guggenheim-Anderson-de Boer (GAB) and Brunauer-Emmett-Teller (BET) equations were applied to discuss the results.

Key words: dark chocolate, cocoa solid content, sorption isotherm, water activity