Study On The Formation Of Food-grade Microemulsions With Tween-80

Food-grade microemulsions were prepared with tween-80 as the surfactant phase (S), ethanol, propylene glycol and glycerol as the co-surfactant phase (CS) and soybean oil, medium chain triglycerides and ethyl butyrate as the oil phase (O) by using titration method. The structure and character of microemulsions were studied. The preparation and character of microemulsions with gingerols were also studied.Whether food-grade microemulsions were easily prepared with tween-80 depended on the structure of oil. It was more easily for short chain fatty acid ester than the long chain one to prepare microemulsions. Ethyl butyrate was the suitable choice as the oil phase, which was also one kind of food flavors. Compared with other food-grade co-surfactants, ethanol was more useful to prepare microemulsions and the forming mechanism was much simpler.Microemulsions made by this research were capable of being clear and transparent or translucent for at least six months, whose particle size was less than one hundred nanometers. Microstructure and structural transition of food-grade microemulsions with tween-80 were studied by detecting their conductivity and viscosity. The conclusions were nearly the same by these two different methods. In the tween-80/ethanol/ ethyl butyrate/water system, water in oil microemulsions were formed with water contents below 50wt.% to 56wt.%. And oil in water microemulsions were formed with water contents above 70wt.% to 72wt.% and bio-continuous microemulsions were formed with water contents between 50wt.% to 72wt.%. More surfactants were capable of advancing a structural transition from water in oil structure to a bio-continuous structure and delaying another structural transition from a bio-continuous structure to the oil in water structure, which eventually led to enlarge the formation zone of bio-continuous microemulsions.Microemulsions with gingerols were clear and transparent for at least six months, which were yellow or dark yellow. Besides, they were capable of being diluted without any change. When water content of microemulsions with gingerols was seventy-five percent, the gingerols contents of microemulsions prepared with soybean oil, medium chain triglycerides and ethyl butyrate were 1.709wt.%, 1.314wt.% and 1.167wt.% at the 9/1 dilution line. Dilution was capable of reducing the gingerols content of microemulsions. Gingerols content of bio-continuous microemulsions was higher than oil in water microemulsions but lower than water in oil microemulsions. Microemulsions with gingerols maintained high stability although they were affected by some environment factors, including centrifugal effect, temperature, salinity and acidity. But the stability of microemulsions with gingerols was a little lower than microemulsions without gingerols.