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Summary: Water is a critical factor influencing the quality of mushrooms. This paper investigated the moisture migration of shiitake mushroom during storage using low‐field nuclear magnetic resonance (LF‐NMR) and magnetic resonance imaging (MRI) and its relationship to quality deterioration. Three water components assigned as water in different cell compartments of cell wall, cytoplasm and vacuole were observed in shiitake mushroom matrix. As the prolonging of storage time, the right shift of immobilised water and left shift of free water led to the merge of these two peaks at the end of storage. The increase in peak area of water in cytoplasm and decrease in the peak area of water in vacuole indicated evident moisture migration from vacuole to cytoplasm. MRI images showed heterogeneous water distribution in shiitake mushroom, and the water migrated from centre to surface, then evaporated to the environment. Besides, the moisture migration might be related to the weight loss and textural softening of shiitake mushroom. [ABSTRACT FROM AUTHOR]

Non-destructive analysis of water dynamics during drying is of importance for quality control of food products. In this study, different water dynamics and migration in Fuji apple slices dried at various hot-air oven temperatures, i.e. 50, 60, 70, and 80 °C and air velocity at 0.2 m/s were monitored using low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI). Multi-exponential fitting of the transverse relaxation T2 parameter demonstrated four distinct water peaks in all samples corresponding to strongly bound, lightly bound, entrapped/immobilized, and free water as follows: T21 in the range of 0.01–1 ms, T22 in the range of 1–10 ms, T23 in the range of 10–100 ms, and T24 in the range of 100–1000 ms, respectively. The water content was measured and analyzed by the traditional technique using the oven drying method. The overall results were highly significant, depicting that the transverse relaxation times T24, signal per mass of the free water A24, and water content significantly decreased (p< 0.05), while the color (L*, a*, b*) and shear force (SF) curves increased with extended drying. Furthermore, good correlations were observed between the LF-NMR parameters and color, water content, and SF in differently processed samples during the dehydration process. Scanning electron microscopy (SEM) and MRI provided the structural changes and spatial water distributions during the drying process. LF-NMR exhibited great potential in evaluating the various water dynamics and quality of Fuji cultivar apples during the drying process. Abbreviations: AA: ascorbic acid; ANOVA: analysis of variance; CPMG: Carr-Purcell-Meiboom-Gill; DW: distilled water; F: Fuji; LF-NMR: low-field nuclear magnetic resonance; MRI: magnetic resonance imaging; SE: spin-echo; SEM: scanning electron microscopy; SF: shear force; SIRT: simultaneous iterative reconstruction technique; TE: echo time; TR: repetition time. [ABSTRACT FROM AUTHOR]

The dynamic states of water in shrimp during drying process were investigated by low-field nuclear magnetic resonance and magnetic resonance imaging. With the extension of drying time, the transverse relaxation time of immobilized and free water significantly decreased, illustrating their mobility reduced. The signal per mass of immobilized water also decreased significantly, indicating its remarkable loss during drying process. Magnetic resonance imaging results revealed that the water signal intensity decreased from the external surface to inner regions of shrimp. Good correlations between the moisture content, hardness, chewiness, cohesiveness, L*, a* and nuclear magnetic resonance T2 parameters were observed by linear regression analysis. [ABSTRACT FROM AUTHOR]

Low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) were used to monitor the water mobility and distribution of Pacific oyster during drying process. The results show the mobilities of bulk, immobilized, and free water were reduced, and the immobilized water was removed dramatically.T2-weighted images displayed the water decrease from the external surface to inner center of oyster during drying. In addition, excellent correlations between the total moisture content andT22andA22were observed with coefficients 0.9777 and 0.9832, respectively. Principal component analysis showed the drying degree of oyster could be monitored based on raw relaxation data. Thus, the result revealed that LF-NMR and MRI have great potential in assessing water mobility and distribution in oyster during drying process. [ABSTRACT FROM AUTHOR]

To detect the water dynamics in abalone during drying is essential for the textural quality improvement, however, sufficiently rapid and nondestructive methods of abalone moisture monitoring are currently lacking. In this study, water changes in abalone during drying and rehydration processes were assessed using low field nuclear magnetic resonance and magnetic resonance imaging. A close correlation was observed between ATotal and the total moisture content, and a prediction model with high correlation (R2 = 0.935) was established. Furthermore, good correlations (R2 > 0.950) between hardness, chewiness, rehydration ratio, and T22 relaxation of dried abalone were observed during the rehydration process. [ABSTRACT FROM AUTHOR]

Turbot is a valuable commercial species due to its high nutrient content. Moisture is an important indicator of meat spoilage. This study elucidated distinctive water dynamics in turbot flesh in the freezing-thawing process by nondestructive low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) techniques. T2 relaxation spectra were utilized to describe the mobility and content of different types of water. Principal component analysis (PCA) revealed a clear discrimination of various freezing-thawing cycles. T1- and T2-weighted MRI provided further visualization of internal information for turbot flesh. Microscopic examination clearly identified protein denaturation and structural shrinkage. Furthermore, NMR parameters and conventional physicochemical parameters of color, shear force and thiobarbituric acid-reactive substances showed good correlations. To sum up, the study revealed that LF-NMR and MRI are promising techniques to portray the relationship between the water dynamics and changes of turbot quality properties during the freezing-thawing process. [ABSTRACT FROM AUTHOR]

Turbot is a valuable commercial species because of its high nutrition content. Water redistribution during heating was attributed to temperature-induced protein denaturation and structural shrinkage. Therefore, knowledge about water dynamics provides valuable information related to flesh physical properties (weight loss, color and shear force). Herein, water dynamics in turbot during baking and microwave heating were elucidated by using low field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI). Four distinct water populations with relaxation times of 0.20-0.60 ms, 2.00-6.00 ms, 30.00-60.00 ms, and 250.00-560.00 ms were identified. The dramatic variation of water populations during baking and microwave heating indicated protein denaturation and structural shrinkage, which was further verified by MRI and microscopic examination. Furthermore, good linear correlations were observed between NMR parameters and weight loss, color and shear force. The results revealed that the water mobility and distribution in turbot provided valuable information for quality analysis during baking and microwave heating. [ABSTRACT FROM AUTHOR]

A new method for imaging the tumor human vascular endothelial growth factor 165 (VEGF 165) is presented. A magnetic resonance imaging (MRI) probe was prepared by crosslinking ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles to the aptamer for tumor vascular endothelial growth factor 165 (VEGF165-aptamer). The molecular probe was evaluated for its in vitro and in vivo activities toward VEGF165. Enzyme-linked immunosorbent assay showed that the VEGF165-aptamer-USPIO nanoparticles conjugate specifically binds to VEGF165 in vitro. A cell proliferation test showed that VEGF165-aptamer-USPIO seems to block the proliferation of human umbilical vein endothelial cells induced by free VEGF165, suggesting that VEGF165 is an effective target of this molecular probe. In xenograft mice carrying liver cancer that expresses VEGF165, T2-weighted imaging of the tumor displayed marked negative enhancement 3 h after the intravenous administration of VEGF165-aptamer-USPIO. The enhancement disappeared 6 h after administration of the probe. These results suggest the targeted imaging effect of VEGF165-aptamer-USPIO probe in vivo for VEGF165-expressing tumors. This is the first report of a targeted MRI molecular probe based on USPIO and VEGF165-aptamer. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract Numerous quality characteristics of food products are dependent on the microstructure and water status. In this study, LF-NMR and MRI techniques were applied for the evaluation of quality and water dynamics in apple jellies of Yinduqing cultivar during the course of 45 days storage. The present study investigated the impact of processing potentiality and formulation of hydrocolloid on water migration in jellies through non-destructive technique. The ingredients utilized in preparing the jelly were 500 mL juice, 400 g/kg sugar with 0, 2.0, 2.5 and 3.0% gelatin, respectively. Transverse relaxation time T 2 exhibited three distinct water fractions (T 21 , T 22 , and T 23) in the jelly samples during processing. Significant correlations were established between LF-NMR and physicochemical parameters. The macromolecular substance and gelatin influenced the water dynamics and caused a considerable variation in the T 1 and T 2 weighted MR images. Thus, the study revealed the feasibility of using non-destructive techniques in determining the dynamics of water within jelly products. Highlights • Apple (Yinduqing) cultivar and gelatin have been used for jelly making. • Processing potential, formulation, storage and their effects on water dynamics were studied. • Three water populations of bound, entrapped and free water were observed during storage. • LF-NMR, MRI and FM can be used for monitoring water dynamics and microstructural changes. • Gelatin 2.5% formulation showed good stability and quality during processing and storage. [ABSTRACT FROM AUTHOR]