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Water Dynamics and Physicochemical Analysis of Two Different Varieties of Apple Jam (Fuji) and (Yinduqing) by LF- NMR and MRI

Abstract:

Apple jam is one of the favorite foods consumed worldwide. This study investigated the effect of storage time and sugar concentration on water dynamics in Fuji and Yinduqing, using low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) techniques. The samples were taken for jam preparation with various concentrations of sugar solution (0, 25, 50 and 75-oBrix) and stored at a room temperature of 20 °C for 16 days. The LF-NMR relaxation time T2 distribution displayed bound, intermediate and free water, respectively. The lowest T2 range reflected lowest sugar hydrogen mobility depending on total soluble solids (TSS) and water content. A significant correlation (r > 0.9) existed between LF-NMR analysis and physicochemical parameters (water content, color, pH and TSS). MRI displayed uniform water distributions in samples with low sugar concentration. Fluorescence microscopy was used to evaluate sugar crystals and microstructural changes during processing. The study demonstrated the viability of LF-NMR method in determining water dynamics in the apple jams upon processing and storage that may be implemented for quality analysis in other jam products.