title: Phase behavior, microstructural transition, antimicrobial and antioxidant activities of a water-dilutable thymol microemulsion.
abstract: Pseudo ternary phase diagrams were constructed to assess the dilutability of thymol microemulsions using non-ionic (Tween 80), cationic (CTAB), and anionic (SDS) surfactants. We successfully constructed a thymol U-type microemulsion system using Tween 80 as surfactant and studied the microstructural transition along the dilution line at a 90/10 surfactant/oil mass ratio, with thymol and ethanol (3:1, w/w) as the oil phase. Differential scanning calorimetry analysis suggested that the microemulsions gradually inverted from the water-in-oil (W/O) (0-20% water) to the bicontinuous (25-35% water), and finally to the oil-in-water (O/W) (40-90% water) microstructures upon dilution, in good agreement with the conductivity measurements, while the rheological results indicated the collapse of rod-like micelles followed by formation of spherical micelles in the O/W region. The activities of the U-type thymol microemulsions are structural dependent. The antimicrobial activity against Escherichia coli and Staphylococcus aureus decreased when the microemulsions transformed from W/O to bicontinuous and O/W structures, while the DPPH scavenging activity increased.
authors.affiliation: College of Biosystems Engineering and Food Science, Fuli Institute of Food Science, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R&D Center for Food Technology and Equipment, Zhejiang University, Hangzhou 310058, China.
authors.forename: Lingli
authors.initials: L
authors.lastname: Deng
authors.affiliation: College of Biosystems Engineering and Food Science, Fuli Institute of Food Science, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R&D Center for Food Technology and Equipment, Zhejiang University, Hangzhou 310058, China.
authors.forename: Maierhaba
authors.initials: M
authors.lastname: Taxipalati
authors.affiliation: Ningbo Entry-Exit Inspection and Quarantine Bureau, Ningbo 315012, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Sun
authors.affiliation: Department of Applied Engineering, Zhejiang Economic and Trade Polytechnic, Hangzhou 310018, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Que
authors.affiliation: College of Biosystems Engineering and Food Science, Fuli Institute of Food Science, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R&D Center for Food Technology and Equipment, Zhejiang University, Hangzhou 310058, China. Electronic address: hubert0513@zju.edu.cn.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D004655:Emulsions; D013943:Thymol / Q000737:chemistry*; D014867:Water
chemical_list: D000890:Anti-Infective Agents; D000975:Antioxidants; D004655:Emulsions; D014867:Water; D013943:Thymol
keywords: Antimicrobial; Antioxidant; Microemulsion; Microstructure; Thymol