Effect of Sugar and Milk Powder Addition on the Mechanical Properties and Texture of Chocolate.

In order to investigate how the addition of two common ingredients in chocolate, sugar and milk powder, affects the mechanical properties of solid chocolate, uniaxial compression tests and wedge fracture tests were carried out using four ratios of chocolate as the experimental material. Mechanical properties such as Young's modulus and fracture toughness were directly correlated with textural properties such as hardness, elasticity, and brittleness. The results show that adding sugar increases Young's modulus and fracture toughness of chocolate, while milk powder is the opposite. In equal amounts of both, sugar played a more substantial role. In combination with the properties exhibited by chocolate in the above tests, data from creep tests were collected to improve the classical Bingham model and develop a new constitutive model for predicting the mechanical behaviour of solid chocolate with different ratios of added sugar and milk powder. The new four-component constitutive model allows for a more accurate fit to the creep test data and this work provides some suggestions for making different tasting chocolates by adjusting the addition of ingredients.