scholarly journals Effects of Glazing with Preservatives on the Quality Changes of Squid during Frozen Storage

2019 ◽  
Vol 9 (18) ◽  
pp. 3847 ◽  
Author(s):  
Mingtang Tan ◽  
Peiyun Li ◽  
Wenhui Yu ◽  
Jinfeng Wang ◽  
Jing Xie
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Shelf Life ◽  
Fluorescence Intensity ◽  
Frozen Storage ◽  
Intrinsic Fluorescence ◽  
Quality Changes ◽  
Low Field ◽  
Lf Nmr

This study aimed to investigate the effects of glazing with sodium polyacrylate (SP) and D-sodium erythorbate (DSE) on the quality changes of squid during frozen storage. Frozen squid samples were randomly divided into seven groups: (1) CK (unglazed); (2) WG (distilled water-glazed); (3) SG (0.1% SP -glazed); (4) SG-1DSE (0.1% SP with 0.1% DSE -glazed); (5) SG-3DSE (0.1% SP with 0.3% DSE-glazed); (6) SG-5DSE (0.1% SP with 0.5% DSE-glazed); (7) WG-1DSE (0.1% DSE-glazed). The efficacy of the different coatings was evaluated using various indicators, such as water holding capacity (WHC), pH value, low field nuclear magnetic resonance (LF-NMR), color, malondialdehyde (MDA) content value, free amino acids (FAAs) content, intrinsic fluorescence intensity (IFI) and the total sulfhydryl content (SH) content. Intrinsic fluorescence intensity (IFI) and low field nuclear magnetic resonance (LF-NMR) were used as fast monitoring techniques to monitor changes in quality of squid samples. The results showed that compared with the CK and WG groups, coating with either SG or DSE alone resulted in reduced rate of moisture loss (p < 0.05), lipid oxidation (p < 0.05) protein degradation (p < 0.05) and prolonged its shelf-life. The combination of glazing treatment with SG and DSE (groups SG-1DSE, SG-3DSE and SG-5DSE) further improved the protective effects of coating, particularly in the SG-3DSE group. Therefore, the glazing of SG-3DSE is recommended to be used to control the quality of frozen squid and to prolong its shelf-life during frozen storage.

scholarly journals Effects of Hydrocolloid Injection on the Eating Quality of Pork Analyzed Based on Low-Field Nuclear Magnetic Resonance (LF-NMR)

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Shengmei Gai ◽  
Zhonghui Zhang ◽  
Yufeng Zou ◽  
Dengyong Liu
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Water Distribution ◽  
Free Water ◽  
Color Difference ◽  
Eating Quality ◽  
Low Field ◽  
Lf Nmr ◽  
Nuclear Magnetic

This study investigated the effects of hydrocolloid injection on the eating quality of porcine meat based on low-field nuclear magnetic resonance (LF-NMR). The eating quality and water distribution of hydrocolloid-injected pork were compared with control, and the principle component analysis (PCA) was applied for the identification of hydrocolloid-injected pork. Total color difference (ΔE∗), cooking loss, and moisture content of hydrocolloid-injected pork were significantly increased compared with the control (p<0.05). LF-NMR indicated that significant differences in the relaxation time and peak area proportion of immobilized water (T21, P21) and free water (T22, P22) were detected among hydrocolloid-injected samples and the control (p<0.05). The first two principal components (PCs) of PCA accounted for 54.07% and 33.56% of the observed variation, respectively. Based on the two PCs, the hydrocolloid-injected pork could be differentiated from the control. Therefore, LF-NMR combined with PCA offers an effective method for the analysis and detection of hydrocolloid-injected pork.

Influence of Freezing–Thawing Cycle on Water Dynamics of Turbot Flesh Assessed by Low-Field Nuclear Magnetic Resonance and Magnetic Resonance Imaging

2018 ◽  
Vol 14 (1) ◽  
Author(s):  
Jiaqi Li ◽  
Kexin Xia ◽  
Yao Li ◽  
Mingqian Tan
Keyword(s):  
Magnetic Resonance Imaging ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Water Dynamics ◽  
Resonance Imaging ◽  
Low Field ◽  
Meat Spoilage ◽  
Thawing Process ◽  
Lf Nmr ◽  
Nuclear Magnetic

AbstractTurbot 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.T2relaxation 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- andT2-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.

Study on Formation and Dissociation of Methane Hydrate in Sandstone Using Low-Field Nuclear Magnetic Resonance Technology

2020 ◽  
Author(s):  
Yunkai Ji ◽  
Jian Hou ◽  
Yongge Liu ◽  
Qingjun Du
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Signal Intensity ◽  
Methane Hydrate ◽  
Hydrate Formation ◽  
Hydrate Dissociation ◽  
Short T2 ◽  
Low Field ◽  
Excess Water ◽  
Lf Nmr

Abstract Natural gas hydrate, as an unconventional resource, has been attracting increasing attention. Understanding the characteristics of methane hydrate formation and dissociation in porous media is important for developing gas hydrate-bearing reservoirs. This work discusses the use of low-field nuclear magnetic resonance (LF-NMR) technology to investigate the formation and dissociation of methane hydrate in the sandstone. In this work, an experimental assembly wherein methane hydrate can form and dissociate, is used to conduct LF-NMR measurements. LF-NMR, as a noninvasive measurement technology, combines the transverse relaxation time (T2) measurement with the magnetic resonance imaging (MRI). T2 measurements can explore the characteristics of methane hydrate formation and dissociation in core samples from a pore-scale perspective. MRI can display the spatial distribution of water from a core-scale perspective. The excess-gas method and the excess-water method are successively applied to form methane hydrate, and depressurization is applied to dissociate methane hydrate in the laboratory. The characteristics of methane hydrate formation and dissociation is studied in the sandstone. Experimental results show that the signal intensity of short T2 and long T2 decreases simultaneously in the process of the methane hydrate formation using the excess-gas method, indicating that methane hydrate is formed in both small and large pores. When using the excess-water method, the signal intensity of long T2 decreases, and the signal intensity of short T2 increases in the process of the methane hydrate formation, indicating that methane hydrate is mainly formed in large pores. Methane hydrate is dissociated simultaneously in both small and large pores when using the depressurization method. Water content in small pores gradually increases. Capillary pressure causes some water to remain in the core samples following dissociation. Water content in large pores decreases initially and then increases during depressurization. In the early stages of depressurization, more water leaves large pores than is generated by hydrate dissociation. In the later stages of depressurization, less water leaves the large pores than is generated by hydrate dissociation. This study may inspire the new understanding on distribution of fluid in sediments during the process of accumulation and exploitation of natural gas hydrates.

Monitoring a typical fermentation process of natto by low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) techniques

2016 ◽  
Vol 8 (39) ◽  
pp. 7135-7140 ◽  
Author(s):  
Jing Wu ◽  
Yanru Li ◽  
Xingsheng Gao
Keyword(s):  
Magnetic Resonance Imaging ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Fermentation Process ◽  
Resonance Imaging ◽  
Low Field ◽  
Magnetic Resonance Imaging Mri ◽  
Lf Nmr ◽  
Nuclear Magnetic

Unique insights into the monitoring of a typical fermentation process of natto based on low field nuclear magnetic resonance (LF-NMR) associated with magnetic resonance imaging (MRI).

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