食品安全现状及食品安全检测

测定5种不同浓度（0%、55%、75%、95%、100%）乙醇云南木姜子醇提物（Ethanol Extract of Yunnan Litsea cubeba，EELC）对两种致病菌的抑菌效应，筛选出抑菌活性最强的醇提取物，并研究其稳定性。采用KB纸片法测定不同浓度乙醇EELC对E.coil、S.aureus的抑菌圈直径，并采用TTC（2,3,5-三苯基氯化四氮唑）法测定其MIC，筛选出最佳抑菌活性EELC，进一步研究其温度、热处理时间、酸碱度及紫外光照稳定性。结果表明：55%和75% EELC分别对S.aureus，E.coil抑制效果最好，其MIC分别为19和819 μg/mL。
在40 ℃下处理55% EELC时，OD₆₀₀为0.118抑菌活性最佳，且在此条件下处理1~5 h抑菌活性保持稳定；经30 W紫外光照射10~60 min抑菌活性无显著差异（P>0.05）；在pH为4时，抑菌活性有所下降，pH为6~10时，抑菌活性保持稳定。在100 ℃处理75% EELC时，抑菌活性保持率达到92.88%，在此温度下加热1~5 h，抑菌活性无显著差异（P>0.05）；在pH为4~8时，75% EELC抑菌活性显著下降（P<0.05），在pH为10时，抑菌活性有所上升；经紫外光照射10~60 min对其抑制效果无显著影响（P>0.05）。综上，55% EELC对S.aureus具有较高的稳定性以及较低的作用浓度，75% EELC对E.coil的抑制效果良好且稳定，为云南木姜子的综合利用与开发提供了理论依据。

Current Situation of Food Safety and Food Safety Inspection

In this study, the antibacterial effects of five different ethanolic concentrations (0%, 55%, 75%, 95%, 100%) EELC (Ethanol extract of Yunnan Litsea cubeba) on two kinds of pathogenic bacteria were determined. Ethanol extracts which had the strongest antibacterial activity and their stability were analyzed. The inhibition zone diameter of different concentrations in ethanolic EELC against E.coil and S.aureus were determined by KB paper method. At the same time, using TTC (2,3,5-triphenyltetrazolium chloride) method detected the MIC of EELC to screen out the best antibacterial activity of EELC. At the end, the temperature, heat treatment time, pH and UV light stability of EELC were further studied. The results showed that 55% and 75% EELC had the best inhibitory effect on S.aureus and E.coli, with MIC of 19 and 819 μg/mL, respectively. 55% EELC treated at 40 ℃, the OD₆₀₀ was 0.118, which had the optimal antibacterial activity. Furthermore, the antibacterial activity remained stable after treatment for 1~5 hours at this condition. There was no significant difference in antibacterial activity between the two groups after irradiation with 30W UV light for 10~60 min (P>0.
05). The bacteriostatic activity decreased at pH4, while it remained at a stable level at pH6~10. 75% EELC was treated at 100 ℃, the retention rate of antibacterial activity reaching 92.88%, and no significant difference was found in antibacterial activity after heating at this temperature for 1~5 h (P>0.05). The antibacterial activity was significantly decreased at pH4~8 (P<0.05), but it showed increasing trend at pH10. UV light irradiation for 10~60 min had no significant effect on the inhibitory activity (P>0.05). It was suggested tha, the 55% EELC had a high stability and low action concentration against S.aureus, while 75% EELC had a stable inhibition effect against E.coil. The results would provide a theoretical basis for the comprehensive utilization and development of Yunnan Litsea cubeba.