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


Berk B., Grunin L., ÖZTOP H. M.

JOURNAL OF FOOD ENGINEERING, vol.292, 2021 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 292
  • Publication Date: 2021
  • Doi Number: 10.1016/j.jfoodeng.2020.110292
  • Title of Journal : JOURNAL OF FOOD ENGINEERING
  • Keywords: Honey, Crystallization, Melting, Time domain NMR, Magic sandwich echo, Relaxation times, TIME-DOMAIN NMR, WATER ACTIVITY, MOISTURE, STATE

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 degrees C. Honey samples were seeded with glucose to induce crystallization. T-1 and T-2 relaxation times were also measured during 96 h of storage. Mono-exponential and bi-exponential relations were used to explain T-1 and T-2, 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. T-1 relaxation times did not change, whereas both components of T-2 decreased with increasing time. In addition to crystallization, the melting of crystallized honey was performed at 50 degrees C inside the NMR system. Crystal melting was monitored in real-time, and the rate of crystal removal was fitted to a monoexponential decay model.