Study On Preparation Of(-)-Epigallocatechin Gallate Nanoliposomes And The Effect On Cod Preservation

(-)-Epigallocatechin gallate(EGCG) is the main active ingredient in tea, with a wide range of biological functions. However, EGCG exposed in the air is easily oxidized, loss of activity, leading to the limit of EGCG application greatly. Nanoliposomes constituted by Lipid bilayer composition, can block out the solution into the interior, protect the drug, and improve the stability and bioavailability of drug. In this study, we prepared EGCG to EGCG nanoliposomes by the lipid nanotechnology, studied the best preparation programs, assessment of stability, and the biological function of EGCG nanoliposomes. Finally, we explored its effect on fresh cod. Specific results are as follows:(1) EGCG nanoliposomes were prepared by reverse evaporation method. Then, we optimized the preparation process by single factor experiments and response surface methodology. Finally we got the best preparation program: cholesterol to lipid ratio of 4, EGCG concentration of 4.88 mg / mL, Tween-80 concentration of 1.08 mg / m L, rotary evaporation temperature of 34.5°C. And in this condition, the prepared EGCG nanoliposomes have the highest encapsulation efficiency of 85.79% ± 1.65%, and a small particle size of 180.2 nm ± 4.3 nm.(2) Leak rate and particle size were used as the index to evaluate stability, we studied the influence of the external environment on the stability of EGCG nanoliposomes. Studies have shown that high temperatures and acidic environment affected the stability of nanoliposomes greatly, and EGCG nanoliposomes should avoid contacting. Ultrasound time helped to prepare a smaller particle size of nanoliposomes, but increased the leak rate, we should control the ultrasonic time. Gastrointestinal fluid simulation experiments showed that nanoliposomes protected EGCG against damage such as pepsin. Finally, stability of EGCG nanoliposomes was at an acceptable level. Within 30 days’ store, the degree of oxidation of liposomal membrane was not obvious, the structure was stable.(3) We explored the biological function of EGCG nanoliposomes through anti-oxidative, anti-bacterial, anti-cancer experiments. In the research of oxidation of white shrimp in the sea, EGCG nanoliposomes effectively slowed the increase in MDA values, and showed a significant antioxidant effect; Through inhibition experiments, we demonstrated its inhibited effect in Pseudomonas fluorescent and Staphylococcus aureus; Using MTT assay and AO/EB method to evaluate the activity of NCI-N87 gastric cancer cells, we have proved that EGCG nanoliposomes have anticancer effects, and the effects were better than EGCG.(4) Using pH, MDA, TVB-N, sensory evaluation and total number of bacterial colony as indicators, we researched the effects of EGCG nanoliposomes on cod(Gadus microcephalus) preservation. Experiments showed that EGCG nanoliposomes effectively mitigated the increase of pH, MDA, TVB-N values. Besides, EGCG nanoliposomes slowed the deterioration rate of cod sensory properties and inhibited microbial growth. Compared with EGCG, EGCG nanoliposomes became more pronounced on preservation effect of cod. Finally, we prepared EGCG nanoliposomes edible film, initially validated its advantages in antibacterial effects of cod, made efficient exploration for the future development of edible wrap.