| Cinnamon oil showed great antimicrobial activity against food microorganism. However, application of cinnamon oil as natural preservative was limited due to its hydrophilic and unstable properties. Microemulsion technology has solubilizing synergistic effect, and the O/W microemulsion system has good stability. Therefore cinnamon oil microemulsion was formulated and its application used in food preservation was studied.Tween 80 and ethanol were selected as surfactant and cosurfactant respectively, the effect of different aqueous phase (containing nisin, sodium phytate or ε-poly-L-lysine·HCl) on the phase behavior of the cinnamon essential oil microemulsion (CEM) system was studied. The pH value, density, electric conductivity, stability, particle size of the O/W microemulsion were measured. In addition, the minimum inhibitory concentration of composite microemulsions against E coli and S aureus were researched. The preservation effect by measuring the volatile base nitrogen, texture profile and microbial characteristic of spiced beef during cold storage were tested. The results of the study are as follows:1) The oil solubilization was dramatically improved of short-chain alcohol, and the solubilization effect was enhanced with the increasing of ethanol content. In this study the ratio of ethanol and cinnamon was determined at 3:1. There is no obvious influence on phase behavior when food preservatives (nisin, sodium phytate and ε-poly-L-lysine·HCl) was at low concentration (<0.5%) into aqueous phase.2) Effect of preservative concentration on microemulsion system characterization was studied. The change of pH or viscosity values was similar between different concentration of the same preservative.3) Effect of different types of preservatives on microemulsion system characterization was researched. Trends of pH value in microemulsion, which nisin or ε-poly-L-lysine·HCl was added into aqueous phase, were consistent with distilled water microemulsion. However, pH value of sodium phytate-microemulsion system was growing. In presen ative-microemulsion system, it was found that electrical conductivity increased as the dissociation of ion, and there was no influence in viscosity value.4) On the dilution tunnel N55,80% aqueous phase was selected as the formula of O/W microemulsion, the ratio of aqueous phase, surfactant, cosurfactant and essential oil was determined at 32:4:3:1. Results showed that microemulsions had good stability and microemulsion particle size had increased significantly after adding nisin. There is no significant difference between other microemulsions.5) Microemulsions showd good antibacterial activity against E coli and S aureus. The antimicrobial activity of microemulsions that adding nisin or ε-poly-L-lysine·HCl for different dosages respectively were improved compared with distill water phase microemulsion. However, there is no significant difference in antimicrobial activity between microemulsions that adding sodium phytate and distill water phase microemulsion.6) Spiced beef treated by microemulsions showed that TVB-N value were reduced inordinately; the texture profile had no obvious influence; significantly reduced to the total bacteria count, groups that treated by MEN and MEP did not overweight (103 and 104cfu/g, respectively). In spiced beef, the presevation effect of MEN is best, MEP takes second place and the effect with MEW is equal with MES. Microemulsion also showed antibacterial activity to E coli and other microorganism, such as lactic acid bacteria.7) The pilot study for microemulsion in enterprise, two microemulsions was applied to flavour goose and sweet-halogen duck’s gizzard, results showed that cinnamon essential oil microemulsion could improve the quality of spiced meat and had great preservation effect. |
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