Non-Conventional Time Domain (TD)-NMR Approaches for Food Quality: Case of Gelatin-Based Candies as a Model Food

The TD-NMR technique mostly involves the use of T1 (spin-lattice) and T2 (spin-spin)<br> relaxation times to explain the changes occurring in food systems. However, these relaxation times<br> are affected by many factors and might not always be the best indicators to work with in food related<br> TD-NMR studies. In this study, the non-conventional TD-NMR approaches of Solid Echo<br> (SE)/Magic Sandwich Echo (MSE) and Spin Diffusion in food systems were used for the first time. Soft<br> confectionary gelatin gels were formulated and conventional (T1) and non-conventional (SE, MSE and<br> Spin Diffusion) TD-NMR experiments were performed. Corn syrups with different glucose/fructose<br> compositions were used to prepare the soft candies. Hardness, °Brix (°Bx), and water activity (aw)<br> measurements were also conducted complementary to NMR experiments. Relaxation times changed<br> (p &lt; 0.05) with respect to syrup type with no obvious trend. SE/MSE experiments were performed to<br> calculate the crystallinity of the samples. Samples prepared with fructose had the lowest crystallinity<br> values (p &lt; 0.05). Spin Diffusion experiments were performed by using Goldman–Shen pulse sequence<br> and the interface thickness (d) was calculated. Interface thickness values showed a wide range of<br> variation (p &lt; 0.05). Results showed that non-conventional NMR approaches had a high potential to be<br> utilized in food systems for quality control purposes.