Application of Low-Field Nuclear Magnetic Resonance Technology in Food and Agriculture: A Literature Review

Magnetic Resonance Imaging (MRI) and analysis technology offers remarkable technical advantages: it is non-destructive, non-invasive, and free of contamination. Measurements are rapid and accurate, enabling real-time data acquisition across both spatial and temporal dimensions. This includes imaging of different cross-sections within a sample and the visualisation of proton activity—crucial for studying material structure and composition. Due to its non-destructive nature, MRI technology is attracting increasing interest from food science researchers worldwide.

Quality Inspection of Fruits and Vegetables

 

MRI technology not only enables the study of internal structures and water distribution in fruits and vegetables but also plays a vital role in assessing ripeness. For certain produce—such as kiwifruit, apples, oranges, onions, and potatoes—external appearance alone is insufficient for detecting internal spoilage or core rot.

MRI offers a reliable solution to this challenge. One of its key advantages in food applications is that it allows for full sample scanning without causing any damage, making it possible to analyse the item while keeping it entirely edible afterwards.

References

 

[1] He Chengyun, Lin Xiangyang, Ruan Rongsheng, et al. Application of Low-field Pulsed MRI Technology in Food Processing [J]. Food Research and Development, 2005, 26(4): 89–93.

[2] Peng Shumei, Lin Xiangyang, Ruan Rongsheng, et al. Applications of Nuclear Magnetic Resonance and Imaging Technology in the Food Industry [J]. Food Science, 2008, 29(11): 712–716.

[3] Pang Linjiang, Wang Yunxiang, He Zhiping, et al. Applications of NMR in Quality Inspection of Fruits [J]. Journal of Agricultural Mechanisation Research, 2006(8): 176–180.

[4] Zhou Ran. Experimental Study on Vibration Damage During Transportation and Cold Storage Quality Change of Pyrus pyrifolia [D].

[5] Zhang Jinsheng. Research on the Application of Nuclear Magnetic Resonance and Imaging Technology in Food Science [D].

 

Oil Content, Moisture Content & Solid Fat Content

 

Oil content analysis of food and seeds: Using NMR (Nuclear Magnetic Resonance) to determine the oil content in oilseed crops is a technology that has been in international use since the early 1960s. While it’s widely adopted overseas, it is still relatively new in China. Compared to traditional methods such as the Soxhlet extraction or the improved direct-drip method, NMR offers advantages including speed, safety, non-toxicity, ease of operation, and the ability to preserve the seed’s integrity. This makes it highly appealing for professionals in grain and oil quality testing.

Moisture content measurement of food/seeds: Rapid and accurate moisture determination is critical in agricultural engineering. Compared with traditional oven-drying methods and other techniques such as neutron, distillation, or infrared analysis, NMR provides superior advantages in terms of speed, accuracy, and ease of use.

Measurement of solid fat content in lipids: Fats and oils play a key role in human nutrition, flavor development, and industrial applications. Accurate quantification of solid fat content using NMR helps advance the understanding of lipid functionality and supports improvements in food processing and product quality control.

Related Articles

 

[1] Xia Tianlan, Liu Dengyong, Xu Xinglian, et al. Application of Low-Field NMR Technology in Moisture Measurement and Quality Evaluation of Meat and Meat Products.

[2] Hao Xiaoli, Zhang Benhua, Zhang Jian, et al. Current Status and Future Outlook of Non-Destructive Grain Moisture Detection Methods [J]. Liaoning Agricultural Sciences, 2004(1): 29-30.

[3] Hao Xiaoli, Zhang Benhua, Wang Jianzhong, et al. Comparative Analysis of Rapid Seed Moisture Testing Methods [J]. China Seed Industry, 2006(1): 11-12.

NMR/MRI-Based Analysis of Water and Oil Distribution in Food

 

Moisture is a major component of food. It plays a key role in determining the physicochemical properties, ensuring food safety, and enhancing flavor. By using MRI technology, the spatial distribution of moisture in food can be monitored in real-time. Moisture distribution models can be established to track dynamic changes in food during processing and storage. If moisture becomes more mobile and unevenly distributed during storage, it can lead to rapid spoilage and a shortened shelf life. Therefore, MRI-based studies on moisture behavior during processing and storage help reveal the mechanisms behind spoilage, optimize production methods, control product quality, enhance food safety, and ultimately extend shelf life.     

MRI enables direct visualization of the spatial distribution of the liquid fat phase in chocolate, helping to evaluate the effects of different temperatures and treatment conditions on fat migration and distribution.    

MRI is an ideal tool for observing the distribution of water and lipids in food. By leveraging differences in relaxation times and resonance frequencies between water and oil protons, specific RF pulses can be selected to enhance one proton signal while suppressing the other. This makes it possible to acquire separate MR images of water and oil, providing valuable parameters for investigating dynamic changes in food structure during processing and storage. 

Related Articles

 

[1] Xia Tianlan, Liu Dengyong, Xu Xinglian, et al. Application of Low-Field NMR Technology in Determining Water Content and Related Quality Attributes of Meat and Meat Products.

[2] Wang Yongwei, Wang Xin, Liu Baolin, et al. Detection of Frying Oil Quality Using Low-Field NMR Technology [J]. Food Science. 2012, 33 (06): 171-175

[3] Li Xianbao, Han Minyi, Fei Ying, et al. Study on the Effect of Microbial Transglutaminase on the Functional Properties of Pork Myofibrillar Protein Gels Using Low-Field NMR [J]. Journal of Nanjing Agricultural University. 2009, 32 (3): 130-134.

[4] Xu Wenwen, Wang Li, Bao Chenwei, et al. Optimization of Composite Phosphate Water-Retaining Agent Using LF-NMR Combined with Response Surface Methodology [R]. Proceedings of the 1st Symposium on Processing Technology and Product Development of Bulk Freshwater Fish. 120-127.

[5] Han Minyi, Fei Ying, Xu Xinglian, et al. Study on the Effect of pH on Heat-Induced Myofibrillar Protein Gels Using Low-Field NMR [J]. Chinese Journal of Agricultural Sciences. 2009, 42 (6): 2098-2104.

[6] Jiang Chao, Han Jianzhong, Fan Jiali, et al. Rapid Detection of Adulterated Milk Using LF-NMR Combined with Principal Component Analysis [J]. Transactions of the Chinese Society of Agricultural Engineering. 2010, 26 (9).

[7] Wu Ye, Xu Ke, Xu Xinglian, et al. Effect of pH on Thermal Gel Properties of Rabbit Myosin Studied by Low-Field NMR [J]. Food Science. 2010, 31 (09).

[8] He Chengyun, Lin Xiangyang, Ruan Rongsheng, et al. Application of Low-Field Pulse Magnetic Resonance Imaging (P-MRI) in Food Processing [J]. Food Research and Development. 2005, 26 (4): 89-93.

[9] Peng Shumei, Lin Xiangyang, Ruan Rongsheng, et al. Application of NMR and MRI Technology in the Food Industry [J]. Food Science. 2008, 29 (11): 712-716.

[10] Wang Na, Chen Weijiang, Lin Xiangyang, et al. Application of Basic Sequences in NMR and MRI Technology in Food [J]. Journal of Agro-Product Processing. 2006, 6: 11-22.

[11] Zhang Jinsheng. Application of NMR and MRI Technology in Food Science [D].

[12] Wen Shengyang, Wang Sujuan, Li Bin. Effect of Freezing on Moisture Content in Konjac Vermicelli Studied by NMR Technology [J]. Food Science. 2012, 33 (13): 96-99.

[13] Zhou Ning, Liu Baolin, Wang Xin. Application of NMR Technology in Food Analysis and Detection [J]. Science and Technology of Food Industry. 2011, 32 (01): 325-329.

[14] Wang Yongwei, Wang Xin, Liu Baolin, et al. Detection of Adulterated Frying Oil Using Low-Field NMR [B]. Proceedings of the Academic Conference on Scientific Instrumentation and Public Welfare. 2011. 157-162.

[15] Chen Fengliang, Wei Yimin, Zhang Bo, et al. Advances in Research on the Role and Behavior of Moisture During Food Extrusion [J]. Food Science. 2009, 30 (21): 416-419.

[16] Wang Qingbiao, Chen Guo, Cao Chen, et al. Study on the Micellization Process of Surfactants in Crowded Environments Using Low-Field NMR [J]. Journal of Instrumental Analysis. 2012, 31 (1): 33-38.

[17] Wan Juan. Processing Technology and Storage Stability Study of Fried and Braised Grass Carp Cubes [D].

[18] Yu Ruixin, Gu Zhiyu, Han Jianzhong. Study on Moisture Changes in Zongzi During Steaming Using Low-Field NMR [J]. Anhui Agricultural Science Bulletin. 2009, 37 (31): 15407-15409.

[19] R. Consonni and L. R. Cagliani. Nuclear Magnetic Resonance and Chemometrics to Assess Geographical Origin and Quality of Traditional Food Products [M].

[20] Minyi Han, et al. Effect of Microbial Transglutaminase on NMR Relaxometry and Microstructure of Pork Myofibrillar Protein Gel. Eur Food Res Technol (2009) 228:665–670.

[21] Jian Sun, et al. Influence of Various Levels of Flaxseed Gum Addition on the Water-Holding Capacities of Heat-Induced Porcine Myofibrillar Protein [J]. Food Chemistry (2011), 76 (3): C472-C478. 

Measurement of Glass Transition Temperature (Tg)

 

Storing food in its glassy state can significantly improve product quality. As such, the glass transition temperature (Tg) is a critical parameter for evaluating various kinetic processes responsible for food spoilage and degradation. These include shrinkage, collapse, crystallisation, and browning during freeze-drying; stickiness and sintering in spray drying; as well as agglomeration and caking during powder food processing and storage—all of which can be explained through Tg measurements.

Commonly used techniques to measure the Tg of food include Differential Scanning Calorimetry (DSC), Differential Thermal Analysis (DTA), Thermomechanical Analysis (TMA), and Dynamic Thermomechanical Analysis (DTMA). However, these methods generally yield an average Tg for homogeneous samples, and may lack precision when evaluating heterogeneous systems—common in many food matrices. Additionally, methods like DSC, TMA, and DTMA have limitations regarding sample shape and state. For instance, TMA and DTMA require relatively large chambers, often leading to water loss during testing.

In contrast, Nuclear Magnetic Resonance (NMR) technology observes the relaxation behaviour of magnetic protons. As food polymers shift from the glassy state to a rubbery state, the mobility of proton-rich functional groups and molecular segments increases. This makes NMR-based proton mobility analysis a powerful and effective way to determine Tg. Advantages include minimal sample preparation, compatibility with various sample forms, rapid data acquisition, high accuracy, non-destructive testing, and the ability to enable real-time, in-line monitoring. During progressive heating, plotting the T1 or T2 values of the food sample against temperature reveals curve inflection points that correspond closely to the sample’s glass transition temperature.

Related Literature:

 

[1] Xu Zhong, Miao Ming. Application of modern polymer physics analytical methods in starch research [J]. Food Science and Technology, 2006, 27(04): 197–199.

[2] Zhao Liming. Study on food glass transition and Tg using DSC and pulsed NMR [J]. Food Technology, 2001(1): 14–17.

[3] Qian Fei, Zhang Jinsheng, Jin Zhiqiang, et al. Study on food glass transition and Tg using NMR techniques [J]. Food Science, 2008, 29(08): 666–669.

[4] Yi Xiaohong, Zou Tonghua, Liu Bin. Application of polymer glass transition theory in drying and storage of food [J]. Food Research and Development, 2007, 28(09): 178–181.