Direct quantification of crystalline content in caramel has proven challenging. Crystal separation techniques are difficult since all steps must be performed carefully so as not to affect the crystal content before measurement. External measurement techniques include X-ray diffraction and high-resolution nuclear magnetic resonance (NMR). X-ray diffraction is not very sensitive and high-resolution NMR is expensive and time consuming; both methods are also limited in caramel due to the crystalline contribution from the fat. Microscopic analysis can be done but is difficult in opaque or highly supersaturated systems and is limited by imaging constraints. One promising, noninvasive measurement technique is Time Domain-Nuclear Magnetic Resonance, or TD-NMR. This technique quantifies the solid fraction of a system and has been
employed with great success in determining solid fat content in lipids. It has also been used to determine crystal content in simple confectionery systems such as fondant where the solid fraction consists solely of sucrose crystals. This technique has yet to be employed in more complex systems that contain solids other than sucrose crystals (e.g., dairy protein and
fat in caramel).