A non-conventional TD-NMR approach to monitor honey crystallization and melting

Abstract

Abstract Crystallization of glucose is a natural process that could occur in honey due to several reasons and glucose is one of them. In this study, a non-conventional TD-NMR pulse sequence, Magic Sandwich Echo (MSE), was used to monitor the crystallization of honey at 14 °C. Honey samples were seeded with glucose to induce crystallization. T1 and T2 relaxation times were also measured during 96 h of storage. Mono-exponential and bi-exponential relations were used to explain T1 and T2, respectively. As a complementary method to NMR, crystal melting enthalpy was measured by differential scanning calorimetry (DSC). High correlations were detected between NMR and DSC results. T1 relaxation times did not change, whereas both components of T2 decreased with increasing time. In addition to crystallization, the melting of crystallized honey was performed at 50 °C inside the NMR system. Crystal melting was monitored in real-time, and the rate of crystal removal was fitted to a mono-exponential decay model.