In this study, a konjac glucomannan (KGM)/ gelatin (GEL)-based film integrated with ginger essential oil (GEO) and rosemary essence oil (REO)-loaded bacterial cellulose was prepared. The synergistic effects of GEO and REO were evaluated. The physicochemical, mechanical, optical, morphological, antibacterial, antioxidant properties, thermal stability and preservation effects of the composite films were characterized. Results demonstrated that GEO and REO exhibited synergistic antibacterial activity when combined in a 3:1 ratio. FT-IR analysis, scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed good compatibility among the components of the film. Furthermore, the incorporation of EOs enhanced various properties of the active film including mechanical strength, barrier performance, hydrophobicity as well as its antibacterial and antioxidant capabilities while also improving thermal stability. Additionally, the active film containing 0.8 % ( w / v ) composite essential oils (KGB-0.8) effectively maintained the quality of refrigerated sea bass and extended the shelf-life for another 6 days.
A 10-week feeding trial, followed by 24-h nitrite stress, was performed to evaluate the effects of dietary selenium-L-methionine (Se-Met) on growth, Se accumulation, antioxidant capacity, transcripts of selenoproteins and histological changes of muscle as well as resistance to nitrite stress in spotted seabass ( Lateolabrax maculatus ) reared at optimal (27 °C) and high (33 °C) temperatures. Five experimental diets were formulated to contain 0, 0.9, 1.8, 3.5, and 7.0 mg Se-Met/kg. Each diet was fed to fish (2.60 ± 0.2 g) in two parallel treatments at 27 or 33 °C. The results showed that elevated temperature (33 °C) induced thermal stress in fish, and fish under thermal stress exhibited lower weight gain (WG) and hepatosomatic index (HSI) but a higher condition factor (CF) compared to those reared at 27 °C. However, the growth and feed utilisation were promoted in L. maculatus with 0.9 to 3.5 mg/kg Se-Met treatments. The protein and lipid content in the muscle increased with the dietary Se-Met level, and the total Se level in the whole body and muscle showed a linear increase with dietary Se-Met supplementation. Thermal stress changed the histology of the muscle, leading to raised levels of malondialdehyde (MDA), reduced antioxidant parameters in the serum and liver, and a decrease in the transcripts of selenoprotein genes in the muscle. Meanwhile, increased antioxidant capacity of serum and liver and up-regulated transcripts of selenoprotein of muscle were observed in L. maculatus reaching a maximum with 3.5 mg Se-Met/kg treatment. After 24 h of nitrite stress, thermal stress exacerbated oxidative damage caused by nitrite stress in L. maculatus . In contrast, dietary Se-Met enhanced the resistance to nitrite stress of L . maculatus fed with Se-Met enriched diets containing 0.9 to 1.8 mg Se-Met/kg. Based on the effects of dietary Se-Met on the growth, antioxidant capacity and resistance to nitrite stress of L. maculatus , this study suggests that the optimal range of Se-Met supplementation in L. maculatus diets is 1.80 to 2.39 mg Se-Met/kg of diet at 27 °C and 1.80 to 4.46 mg Se-Met/kg of diet at 33 °C.
危险品化学品经营许可证（带存储）