This study investigated and determined the changes in various qualities of tuna samples that were glazed with rosmarinic acid, a bamboo leaf antioxidant, and sodium lactate and stored at −18 °C for 180 days. The water-holding capacity, cooking loss, color, texture, protein content, and total volatile basic nitrogen (TVB-N) were monitored, to study the effect of tuna glazed with different materials on the quality every 30 days. Low-field nuclear magnetic resonance (LF-NMR) was used to measure the water distribution of tuna in this paper. The results showed that the quality of unglazed tuna decreased significantly after 180 days of frozen storage. During frozen storage, the hardness anda* values of RG (glazed with the rosmarinic acid group), SG (glazed with the sodium lactate group), and CG (glazed with the composite of rosmarinic acid, sodium lactate, and the antioxidant of bamboo leaf) tuna decreased slowly, while the malondialdehyde (MDA) value of AG (glazed with the antioxidant of bamboo leaf group) tuna increased slowly. After 180 days of frozen storage, CG tuna had the highest protein content and the lowest TVB-N value, which may have been due to the synergistic effect of glazing materials. The tuna with CG also had the best freshness and quality after frozen storage. Considering the results, a composite of rosemary (0.3%), sodium lactate (3.4%), and antioxidants of bamboo leaves (0.12%) is the best material for glazing tuna.Keywords:glazed tuna;rosmarinic acid;sodium lactate;antioxidant of bamboo leaf;frozen storage
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.Keywords:squid;glazing;frozen storage;sodium polyacrylate;D-sodium erythorbate;quality
Summary The quality of fish is easily damaged during the frozen process, and the ice glazing technology can better maintain the quality of frozen fish. However, the traditional ice glazing technology is not yet stable and some of the properties need to be improved. This research optimised ice glazing technology by adding different antioxidants to the traditional ice glazing, which improved the stability of the ice glazing and lessened the dry consumption of mackerel during frozen storage. The lipid oxidation and protein denaturation of mackerel were inhibited with the addition of antioxidants to the ice glazing, the freshness of mackerel was maintained better, and the production of histamine was also decreased during frozen storage. It was found that the ice glazing with the addition of antioxidant bamboo leaves (AOB) had better water retention, lower TVB-N value, and histamine content compared to the addition of theaflavins (TF) and sodium isovitamin (VC). Moreover, the sample treated by the ice glazing with AOB showed less lipid oxidation and protein denaturation. Therefore, ice glazing with the addition of AOB could be an optional method for relieving the quality deterioration of mackerel during frozen storage. This research also provides insights into the coupling of antioxidants and ice-coating techniques.
危险品化学品经营许可证（带存储）