Study On The Antibacterial Activity And Mechanism Of Hexahydro-β-Acids Methyl-β-Cyclodextrin Inclusion Complex

β-acids was composition of soft resin in hops,but the application ofβ-acids was limited due to its instability.Hexahydro-β-acid was derived from hydrogenation ofβ-acids in hops,not only has high stability,but also had antioxidant,antibacterial and anti-inflammatory activity.But the application in water-based systems of HBA was limited due to its poor solubility.So,if the solubility of HBA was improved,it could be used as preservative in more food systems,not only broadened the application filed of hops,but also provided a natural plant-derived preservative for food field.The paper used HBAasrawmaterialtomakemethyl-β-cyclodextrin（M-β-CD）and hydroxypropyl-γ-cyclodextrin（HP-γ-CD）into inclusion complex with HBA,and the solubility of HBA was improved.The antibacterial activity of inclusion complex against14 strains（include Staphylococcus aureus and so on）was studied.The effects of metal ions,reducing agents,oxidants and preservatives on the antibacterial activity of HBA/M-β-CD were investigated.The antibacterial mechanism of HBA/M-β-CD was further studied.Finally,the inclusion complex is applied to the storage of salted ham and the main tasks as follows:HBA/M-β-CD and HBA/HP-γ-CD inclusion complexes were prepared by grinding method.The antibacterial activity on 14 strains and reducing ability of the two inclusion complexes on were investigated.The result showed that Staphylococcus aureus was significant sensitive to HBA/M-β-CD inclusion complex and MIC was 16.25μg/mL.Bacillus cereus was most sensitive to HBA/HP-γ-CD inclusion complexes and MIC was16.25μg/mL.Two inclusion complexes have no inhibitory effect on Streptococcus pneumoniae,Enterococcus faecalis,Salmonella paratyphi A,Pseudomonas aeruginosa and Proteus mirabilis.The antibacterial activity was slightly lower than that of HBA methanol solution,75%alcohol had no antibacterial effect on Streptococcus pneumoniae,Enterococcus faecalis and Pseudomonas aeruginosa,but had slight antibacterial effect on other strains.Potassium sorbate had no antibacterial effect on all strains.The effects of metal ions and some food additives on the antibacterial activity of HBA/M-β-CD inclusion complex were studied.The results showed that the constant metals ion,Na₂NO₂ and sodium benzoate had no effect on the antibacterial activity of the inclusion complex.Fe²⁺,Fe³⁺,Cu²⁺,potassium sorbate and H₂O₂ had inhibitory effects on the antibacterial activity of the inclusion complex.Na₂SO₃ can enhance the antibacterial activity of the inclusion complex against Enterobacter sakazakii,and KMnO₄ can significantly inhibit the antibacterial activity of inclusion complex,and inclusion complex had no antibacterial activity at high concentration.The metal ion complex is consistent with the effect of the single component.The antibacterial mechanism of the inclusion complex was investigated.The results showed that the growth of Staphylococcus aureus and Enterobacter sakazakii was significantly slower after the addition of HBA/M-β-CD inclusion complex,and the difference was not significant when the concentration was high and low.SEM found that the surface of Staphylococcus aureus was rough and concave and the surface of Enterobacter sakazakii was rough,wrinkled and atrophied.The conductivity and OD_260nm60nm of the culture medium increase significantly with time,and the increments were increase when concentration increases.The SDH enzyme activity was significantly reduced.The application of HBA/M-β-CD inclusion complex in western ham was studied.The result showed that the inclusion complex could replace potassium sorbate to inhibit the growth of bacteria during ham storage,and reduce nitrite,stabilize the biological environment during storage,but the inclusion complex could not replace the sodium nitrite to enhance the color and protect the color.