Center for Paralysis Research, Purdue University, West Lafayette, IN 47906, USA.
Department of Food Science, Purdue University, West Lafayette, IN 47906, USA.
Food Chem. 2017 Oct 1;232:191-197. doi: 10.1016/j.foodchem.2017.03.147. Epub 2017 Apr 1.
In this work, we prepared various sub-micron thymol emulsions with high hydrophilic-lipophilic balance (HLB) surfactants via spontaneous emulsification. Emulsion properties, such as size, polydispersity and charge, were assessed for each surfactant type and mass fraction. Emulsion stability was characterized by monitoring droplet size following exposure to physical (centrifugation) and thermal stressors (freeze, thaw cycling). Emulsions were subsequently screened against several challenge pathogens to evaluate antimicrobial efficacy. Based on these time-kill assays, exemplary formulations were further tested as sanitizing washes on lettuce and blueberries inoculated with food-borne bacterial biofilms. Antimicrobial data elucidate both surfactant and formulation specific antagonisms between thymol and the emulsifying agents. However, the best emulsion compositions were capable of reducing planktonic bacteria by >4 logs and biofilm bacteria by 1.5-2.5 logs in 60 s. These results are comparable to the efficacy of chlorine at ∼50-200ppm. The experimental results have implications in emulsion formulations involving thymol and other terpenoids.
在这项工作中，我们通过自发乳化制备了各种具有高亲水亲油平衡（HLB）值的叔醇亚微米乳液。评估了每种表面活性剂类型和质量分数的乳液性质，如粒径、多分散性和电荷。通过监测暴露于物理（离心）和热应激（冷冻、解冻循环）后液滴尺寸来表征乳液稳定性。随后，用几种挑战性病原体对乳液进行筛选，以评估抗菌功效。基于这些时间杀伤试验，进一步将代表性配方用作接种了食源性病原体生物膜的生菜和蓝莓的消毒清洗液。抗菌数据阐明了叔醇与乳化剂之间的表面活性剂和配方特异性拮抗作用。然而，最好的乳液配方能够在 60 秒内使浮游菌减少 4 个对数级以上，生物膜菌减少 1.5-2.5 个对数级。这些结果与 50-200ppm 左右的氯的功效相当。实验结果对涉及叔醇和其他萜烯的乳液配方具有重要意义。
