Introduction: Melting is the change of a solid into a liquid when heat is applied. Melting will occur at a fixed temperature which known as melting point. Melting point is the temperature at which the solid and liquid forms of a pure substance can exist in equilibrium. The temperature will increase until the melting point is reached when heat is applied. Heat will convert the solid into a liquid with no temperature change. Temperature of the liquid will raise when the entire solid has melted. An impure solid generally melts over a range of temperatures below the melting point of the principal component.
Discussion:
The main application of melting is chocolate moulding. Cocoa butter, one of the main ingredients used to produce
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In Form III and IV, chocolate is firm, but don’t give a good ‘snap’, and show some blooming. The optimal polymorphic form for large-scale manufacture and consumption is Form V. To ensure this, the raw chocolate has to be tempered to allow the crystals to form in an orderly fashion giving the coveted “melt-in-the-mouth” feel. The reason for tempering the chocolate is to ensure than the chocolate only exists in the β (V) polymorph which is the most desirable for consumption as it melts only in the mouth and not in the hand. In Form VI, the chocolate is hard and melts slowly in the mouth and show some blooming. The higher the number, the more thermally stable the structure is.
The melting properties of cocoa butter and chocolate are very important, as the melting is what delivers the ‘feel’ and taste of the chocolate to the mouth. It becomes important to characterize and understand the melting properties of the chocolate as it is related to essential consumer aspects. One of the best analytical techniques for this purpose is differential scanning calorimetry (DSC). Differential Scanning Calorimetry measures the heat flow into or from a sample under heating, cooling or isothermal conditions. It has been used to study cocoa butter crystallization and melting either pure or in