| Meat and its products are rich in protein,fat and moisture,which make them very suitable for the growth of microorganisms.And B.cereus,one of the main pathogenic bacteria in meat products,can produce heat resistant spores,and the spores could activiate when temperature increased.Cinnamon essential oil(CEO)could suppress the unwanted smell of meat,inhibit the growth of bacteria and has the activity of antioxidation.However,volatile and thermal instability of CEO will affect its antibacterial effect when used in food directly.Therefore,CEO/?-CD was encapsulated into engineered liposomes inlaid with casein.Then,the controlled release of proteoliposomes-encapsulated CEO/?-CD was realized via bacterial protease secreted from B.cereus.Last,the PEO/proteoliposomes-encapsulated CEO/?-CD nanofibrous membranes,electrospun for the application in beef,are non-toxic and biodegradable.In this study,the antibacterial activity and mechanism of CEO against B.cereus were researched.Then,the physical properties,release characteristics and antibacterial effect of proteoliposomes containing encapsulated CEO/?-CD were evaluated.Next,the release characteristics and antibacterial effect of PEO proteoliposomes-encapsulated CEO/?-CD nanofibrous membranes were studied.Last,its application in beef was evaluated.The main results are as follows:(1)The main component of CEO was eugenol(75.61%).The MIC and MBC of CEO against B.cereus were 0.25 mg/mL and 0.5 mg/mL respectively.CEO might increase the permeability of cell membrane and affect the synthesis of DNA,leading to the leakage of the intracellular substances.(2)The optimal preparation condition for CEO/?-CD: the ratio of CEO and ?-CD was 1:9,the inclusion temperature was 50 ?,and the inclusion time was 2.5 h.The inclusion rate and embedding rate of CEO/?-CD under this condition were 67.12 ± 1.02% and 82.33 ± 0.66%,respectively.(3)In the case of 20 mg/mL CEO/?-CD concentration,the average partical size of CEO/?-CD proteoliposomes was suitable,with a PDI of 0.063 ± 0.003.The Zeta potential was-43.2 ± 2.16 mV.The encapsulation efficiency of CEO was 79.53 ± 1.59%.The embedding rate of protein was 82.33 ± 0.66%.(4)The release rates of CEO/?-CD proteoliposomes were 62.35 ± 3.12% and 86.74 ± 4.34% respectively after incubation for 2 d and 4 d.After B.cereus treatment,the characteristic peak of eugenol was redetected by GC-MS,which verified the release of CEO from proteoliposomes.(5)The diameters of PEO nanofibrous membranes were usually ranged from 400 nm to 500 nm.It has been found that the diameters of nanofibers become larger when CEO/?-CD proteoliposomes were added simultaneously.The diameters of proteoliposomes-encapsulated CEO/?-CD nanofibrous membranes were mostly 800 nm~900 nm.The release rate of proteoliposomes-encapsulated CEO/?-CD nanofibrous membranes was about 80% after incubation for 2 d.The antibacterial experiment was indicated that the proteoliposomes containing CEO/?-CD can accurately inhibit bacterial multiplication by the stimulus-response of B.cereus protease to casein.(6)The results demonstrated that CEO/?-CD proteoliposomes nanofibrous membranes on silver paper,food wrapping paper and plastic wrap had a significant antimicrobial effect on B.cereus in beef.And the treatment of nanofibrous membranes could not only inhibit and eliminate the B.cereus,but also maintain the quality of beef.After treated by CEO/?-CD proteoliposomes nanofibrous membranes for 2 d,the population of B.cereus in beef was reduced more than 90%. |
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