| SEO is a natural plant extract often used for physiotherapy and spices,in recent years,because of its good antioxidant and bacteriostatic activity,it has a good application prospect in the field of food preservation.But due to the instability of its physicochemical properties,its further application has been limited.This paper first explored the bacteriostatic mechanism of SEO against S.aureus,and then the stability of SEO was improved by cyclodextrin coating technology,and a composite hydrogel containing cyclodextrin complex prepared with gelatin and sodium alginate as hydrogel substrates was further characterized,and it was finally applied to the preservation of fresh meat.The main research contents and conclusions of this paper are as follows:（1）Inhibitory mechanism of SEO on S.aureus.Firstly,the main chemical composition of SEO was analyzed and determined,and the inhibitory mechanism of SEO on S.aureus was studied.The results showed that the main components of SEO were carvacrol and p-cymene.The results of antimicrobial experiments showed that SEO had a significant inhibitory effect on S.aureus at lower concentrations.By studying the changes of various indicators of S.aureus before and after SEO treatment,the antibacterial mechanism of essential oils was preliminarily explored,and the interaction between the main components of SEO and the DNA of S.aureus was further studied by fluorescence analysis and molecular docking.The results demonstrateed that SEO inhibited bacterial growth by altering cell membrane permeability of S.aureus,causing leakage of the contents.After the barrier function of bacterial cell membrane was damaged,the small molecular components of SEO may enter the cell to compete with DNA,affecting the conformation and activity of DNA,and ultimately the physiological metabolism of bacteria was inhibited.（2）Preparation and characterization of SEO/methyl-β-cyclodextrin inclusion complex（SEO/MβCD-ICs）.First of all,the study showed that the formation of SEO/MβCD-ICs can significantly improve the solubility of SEO in water.The optimal preparation protocol for the obtained inclusion complex（IC）is:SEO:MβCD=1:9（w/w）,reaction temperature is 60°C,reaction time is 2 h.The formation of IC was confirmed by the Fourier alternating infrared spectroscopy（FTIR）and X-ray diffraction analysis,etc.Finally,the antibacterial and antioxidant activities of SEO/MβCD-ICs were evaluated.The SEO/MβCD-ICs have a high inhibition rate against S.aureus,and the DPPH free radical clearance was proportional to the amount of SEO/MβCD-ICs added.The inclusion of cyclodextrins improved the solubility and stability of SEO.（3）Preparation and performance evaluation of gelatin/sodium alginate composite hydrogel containing SEO/MβCD ICs.In this chapter,gelatin and sodium alginate were used as the main raw materials,and the optimal gel-forming system was determined by evaluating the texture parameters of hydrogels prepared with different formulations by glutamyl transaminase（TG）and Ca2+double cross-linking method.FTIR was used to analyze the crosslinking mechanism of the hydrogel.Swelling experiments demonstrated that the composite hydrogel has a certain temperature and p H sensitivity.In addition,the composite hydrogel can achieve the controlled release of SEO through stimulation of different environmental conditions,and it showed a good inhibitory effect against S.aureus.Applied experiments have shown that the Gel/Alg@ICs composite gel film has a good effect on fresh meat preservation,which can significantly inhibit the growth of S.aureus,and delay the change of color and texture of pork.This further promoted the application of composite hydrogel in the food packaging field.In this study,Gel/Alg interpenetrating network hydrogels were prepared by double crosslinking method,and a new composite hydrogel material was constructed by adding SEO/MβCD-ICs,which laid the foundation for the development of plant essential oil/cyclodextrin inclusion complex and the study of hydrogel active materials. |
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