不同加工条件对茶黄素抑制单增李斯特菌稳定性的影响

Effects of different processing conditions on the inhibitory stability of theaflavins against Listeria monocytogenes

目的探讨不同加工条件对茶黄素(theaflavins,TFs)抑制单增李斯特菌(Listeria monocytogenes,LM)稳定性的影响。方法以LM为指示菌,采用二倍稀释法测定TFs的最小抑菌浓度(minimum inhibitory concentration,MIC),并在此基础上通过牛津杯法进一步探究不同加工条件中的环境因素(加工温度、pH、NaCl)和食品基质(脱脂奶粉、卵磷脂、蔗糖)对TFs抑菌稳定性的影响。结果TFs对LM的MIC为2.00 mg/mL,此时的抑菌效果为中敏水平,LM的正常生长被明显抑制;加工温度在25~121℃时,TFs对LM的抑菌圈直径无显著性差异;pH在2.0~10.0时,其抑菌圈直径从12.74 mm显著降低至9.86 mm;NaCl浓度在0.2~0.8 mol/L时,其抑菌圈直径有所增加;脱脂奶粉质量浓度在20.00~60.00 g/L时,其抑菌圈直径显著降低;卵磷脂质量浓度在2.00~12.00 g/L和蔗糖质量浓度在10.00~60.00 g/L时,其抑菌圈直径无显著性变化。结论TFs对LM具有较好的抑菌活性且在不同加工条件下能保持良好的抑菌稳定性。本研究为TFs作为一种新型抗菌配料在食品加工和贮藏中的应用提供了理论依据。

Objective To investigate the effects of different processing conditions on the inhibitory stability of theaflavins(TFs)against Listeria monocytogenes(LM).Methods With LM as the indicator bacteria,the minimum inhibitory concentration(MIC)of TFs was determined through the double dilution method,and the effects of different processing conditions including environmental factors(processing temperature,pH,and NaCl)and food matrices(skimmed milk powder,lecithin,and sucrose)on the antibacterial stability of TFs were further explored via Oxford cup method afterwards.Results The MIC of TFs against LM was 2.00 mg/mL,and their antibacterial effects were at the medium sensitive level,showing that the normal growth of LM was inhibited apparently;when the processing temperatures were 25‒121℃,the inhibition zone diameters of TFs against LM were not significantly different;when the pH values were in the range of 2.0‒10.0,their corresponding inhibition zone diameters decreased significantly from 12.74 to 9.86 mm;when NaCl concentrations were 0.2‒0.8 mol/L,their corresponding inhibition zone diameters increased slightly;when the mass concentrations of skimmed milk powder were in the range of 20.00‒60.00 g/L,their corresponding inhibition zone diameters decreased significantly;when the mass concentrations of lecithin and sucrose were 2.00‒12.00 g/L and 10.00‒60.00 g/L,there was no significant change for their corresponding inhibition zone diameters.Conclusion TFs possess a strong antibacterial activity against LM,and can maintain a good antibacterial stability under different processing conditions.This study provides a theoretical basis for the application of TFs as a new antibacterial ingredient in food processing and storage.