A non-invasive method based on low-field NMR to analyze the quality changes in caviar from hybrid sturgeon (Huso dauricus, Acipenser schrenckiid )

Abstract

A noninvasive LF‐NMR method was developed to monitor proton dynamics on caviar stored at −4°C for 11 months. T2 relaxation spectra revealed three peaks at 0.54–0.75, 20.61–30.78, and 147.24–307.37 ms, respectively, whereas T1 showed only one peak around 167.16–217.31 ms. The T21 and T22 components remained unchanged during the storage period, while T23 was irregularly changed. NMR analysis demonstrated the moisture migrated through the extracellular spaces as free water under the action of osmotic pressure gradient during the salting treatment. Moisture and fat contents in caviar remained unchanged during the overall storage time. There was a trend for increased TVB‐N values over the 11 months storage. Color measurement was carried out to evaluate the quality change of the caviar. The NMR parameters clearly showed good correlation with moisture. Practical applications Caviar is one of the most expensive fishery products which not only contain protein, but also essential amino acids, trace elements, vitamins and high unsaturated fatty acids. The monitoring and analysis of the quality changes of caviar are essential during the period of caviar processing and storage. Herein, the low‐field nuclear magnetic resonance (LF‐NMR) and magnetic resonance imaging (MRI) methods were developed and tested to assess the proton changes of caviar during cryopreservation at −4°C for as long as 11 months. The use of LF‐NMR and MRI technique is fast, noninvasive, inexpensive, and visualization results are expected. This approach developed in this study is quite general and can be applied to monitor the proton changes of caviar storage in a noninvasive and fast way.

Low-Field NMR and MRI to Analyze the Effect of Edible Coating Incorporated with MAP on Qualities of Half-Smooth Tongue Sole (Cynoglossus Semilaevis Günther) Fillets during Refrigerated Storage

“…Analysis was performed according to the method proposed by Huang et al [11] with following modifications. Portions of 3 × 3 × 1 cm (about 5 g) were cut from the dorsal part of fillets and sealed with polyethylene films.…”

“…However, low-field NMR (LF-NMR) and magnetic resonance imaging (MRI) techniques have more advantages in decreasing cost, saving time, and reducing damage to samples compared with the above instruments [4,10,11]. In addition, LF-NMR and MRI are able to assess the quality changes by providing the distribution as well as structural information of protons from water and lipid [12][13][14].…”

Effect of carboxyl content on the physicochemical properties and intramolecular water distribution of 6‐carboxyl chitooligomer prepared by laccase‐TEMPO

“…The transverse ( T 2 ) relaxation times of Lac‐T 1%, Lac‐T 2%, Lac‐T 4%, Lac‐T 8%, and Control samples are shown as Figure . Two peaks were observed in the T 2 relaxation spectra, suggesting the existence of two distinct water populations, that is, bound water (strongly bound to polysaccharide polymers and which does not flow, T 21 ) and immobile water (close to outer layer spaces of bound water, T 22 ) . The amplitudes of the T 21 and T 22 peaks of oxidized chitooligomer were significantly higher than those in the Control sample.…”

Effect of pre‐frying on distribution of protons and physicochemical qualities of mackerel

“…In addition, the combination of LF‐NMR and partial least squares regression (PLSR) model could be used to predict the quality of dried oyster products, 26 and to analyse the content of water, fat and protein of caviar during storage 27 . Furthermore, the characteristics of sea cucumber in freeze–thaw cycles could be detected by LF‐NMR 28 …”