Terahertz Non-Contact Monitoring of Cocoa Butter in Chocolate

Abstract

Chocolate is widely enjoyed in many sweets and foods all over the world. In cocoa butter, fatty acids combine together and give cocoa butter 6 different types of crystals: γ, α, β’(III), β’(IV), β(V) and β(VI). In the industry, the β(V) form that is required, is metastable and gives chocolate its marketable properties. The β(VI) form is also stable but not desirable, because of fat bloom. The objective of this study is to characterize these polytypes by terahertz (THz) spectroscopy. THz spectroscopy is expected to be a new tool in food industry, as THz energy corresponds to collective molecular macro-vibrations. Two chocolates from different factories were inspected with optical microscope, X-ray diffraction (XRD) and THz spectroscopy. Optical microscope showed different surface aspects, XRD showed the same species in the two brands and THz spectroscopy showed different features. These differences may be due to fatty acids combination of chocolate.