Effects of apple polyphenols and chitosan‐based coatings on quality and shelf life of large yellow croaker (Pseudosciaena crocea) as determined by low field nuclear magnetic resonance and fluorescence spectroscopy

Abstract

In this study, the effects of apple polyphenols (AP) with chitosan (CS) coating on quality enhancement of large yellow croaker (Pseudosciaena crocea) during ice storage was assessed. Microbiological (total viable counts [TVC], psychrophilic bacteria counts [PBC], H2S‐producing bacteria counts, Pseudomonas bacteria counts) and physicochemical (K‐value, total volatile basic nitrogen [TVB‐N], thiobarbituric acid [TBA], water‐holding capacity [WHC] and color difference) indicators were measured periodically. Meanwhile, low field nuclear magnetic resonance (LF‐NMR), magnetic resonance imaging (MRI), and fluorescence spectroscopy were used to study the changes in moisture and lipid. The results showed that AP combined with CS could inhibit the increase of TVC, K‐value, TBA, and TVB‐N. Meanwhile, the results of LF‐NMR showed that group treated with 1.0%AP + 2.0%CS was superior in water retention, but overall water loss in different groups was less, which was similar to the change of WHC. For fluorescence intensity analysis, 1.0%AP + 2.0%CS group showed a slower increase than other groups during whole storage period, which was consistent with TBA value. In conclusion, the shelf life of large yellow croaker in control group was 8 days, while 1.0% AP combined with 2.0% CS could retard the quality deterioration and prolong the shelf life for another 8 days.

Effect of multi-frequency ultrasound assisted thawing on the quality of large yellow croaker (Larimichthys crocea)

“…5 ). In the MRI results, the redness in the figure represents a high proton density region, and the blueness represents a low proton density region [41] . Because of the degradation of fish muscle during the freezing and thawing process, the MRI results in the thawed samples all became bluer and darker than that of the FS samples, indicating that the moisture contents in the samples were reduced.…”

Structural changes and molecular mechanism study on the inhibitory activity of epigallocatechin against α-glucosidase and α-amylase

“…The EGC solution was thoroughly mixed with the α-glucosidase and α-amylase solutions (V/V = 1/1) and was incubated at 37°C for 10 min before its fluorescence absorbance was measured. The excitation wavelength was 280 nm, and the scanning range was 290–500 nm, with a scanning interval of 5 nm ( 23 ).…”

Effects of immersing treatment of curcumin and piperine combined with vacuum packaging on the quality of salmon (Salmo salar) during cold chain logistics

“…Figure 3E Shows the MRI of salmon under different treatments in the cold chain logistics process, in which the different colors represent the moisture content. The redness means higher moisture content, and the blueness represents the low moisture content ( 68 ). With the increasing storage time, all groups showed a color change from red to blue, and the color of CK-TFT was significantly bluer and darker than the other groups, indicating that CK-TFT had the most severe water loss.…”