Field gradient CPMG applied on postmortem muscles

Simultaneous, Rapid and Nondestructive Determination of Moisture, Fat Content and Storage Time in Leisure Dried Tofu Using LF-NMR

Leisure dried tofu is a kind of small packaged food which is popular with consumers in China. However, during the storage of leisure dried tofu, moisture and fat may be lost and deteriorate. For their own benefit, bad business operators might forge or mark the production date and shelf life. Therefore, it is necessary to explore a method to determine simultaneously the moisture, fat content, and storage time of leisure dried tofu. Samples were measured for obtaining transverse relaxation data by using low-field nuclear magnetic resonance (LF-NMR) spectrometer. The experimental data were analyzed and modeled by methods including partial least squares (PLS) or back-propagation artificial neural network (BP-ANN). The results show that the models can be used to predict the moisture, fat content, and storage time rapidly, nondestructively, accurately, and simultaneously. Furthermore, in order to explore the changes of nutrients in leisure dried tofu with the storage time, the storage dynamics of moisture and fat was considered by a using corresponding calibration model.

Study on water proton distribution and flow status of starch during the hydration process

The hydration process of starch significantly affects the quality of starch-based food, especially for samples with medium to low water content. In this paper, rice starch, as a representative of cereal starch, and potato starch were chosen as the samples. The proton distributions and flow status of the hydrated rice starch and potato starch with moisture contents of 20-90% and the causes of the differences between them were investigated by ¹H LF-NMR. The longitudinal and transverse proton relaxation (T₁ and T₂) of the two starch systems was obtained using the inversion recovery (IR) sequence, the free induction decay (FID) sequence, and the multi-pulse echo CPMG sequence. Through the detection of longitudinal relaxation, two different populations were found in the two hydrated starch systems, and the changes were linearly related to the moisture content. Through the detection of transverse relaxation, two populations were distinguished in the hydrated rice starch samples with different moisture content, whereas two to four different populations were detected in the hydrated potato starch samples. Because of the differences in particle size and swelling capacity, hydrated potato starch showed greater proton freedom and more observable types of protons than hydrated rice starch.

Low-field permanent magnets for industrial process and quality control

In this review we focus on the technology associated with low-field NMR. We present the current state-of-the-art in low-field NMR hardware and experiments, considering general magnet designs, rf performance, data processing and interpretation. We provide guidance on obtaining the optimum results from these instruments, along with an introduction for those new to low-field NMR. The applications of lowfield NMR are now many and diverse. Furthermore, niche applications have spawned unique magnet designs to accommodate the extremes of operating environment or sample geometry. Trying to capture all the applications, methods, and hardware encompassed by low-field NMR would be a daunting task and likely of little interest to researchers or industrialists working in specific subject areas. Instead we discuss only a few applications to highlight uses of the hardware and experiments in an industrial environment. For details on more particular methods and applications, we provide citations to specialized review articles.