In this study, lemon essential oils (LEOs) were extracted from lemon peels by using nonionic microemulsions which could avoid the problem of residual organic solvent and energy consumption. At first, the stability of the microemulsion formulations, including P123/Tween80 (in 1/4 mass ratio), P123/PE 64 (in 1/4 mass ratio) and P123/T20 (in 1/2.5 mass ratio), was examined by size measurements with the dynamic light scattering (DLS). The results showed that P123/Tween 80 was the most stable one during a test duration of 21 days. With the good storage stability, the P123/Tween80 system could satisfactorily form microemulsions and extract LEOs from peels. Effects of various parameters including the mixed ratios of surfactants, the dosage of surfactants and the concentrations of micellar solutions, as well as the procedures of the dynamic extraction, were all investigated in attempt to optimize the extraction condition. The results of LEOs extraction obtained by using 6 wt% P123/Tween80 after 24 h indicated an LEO extraction efficiency of 59.2% and 50.2% for fresh and waste peels, respectively. Moreover, the preconcentration technique was well used with sodium sulfate added to dramatically decrease the cloud point of the three formulations. Under the optimal condition, the preconcentration factor of P123/Tween80 was more than 20 and the most in all mixed surfactants used in this work. On the other hand, the antibacterial activity was determined against bacteria using growth curve and disc diffusion method under in vitro conditions. The commercial LEOs and extracted LEOs had fairly better activity against Bacillus cereus, compared with Escherichia coli BL21(DE3) and Proteus hauseri ZMd44. It is also found that the antibacterial effect of LEOs could be further improved by using preconcentration technique, leading to the higher concentration of LEOs present.

Extraction of lemon essential oils from lemon peels with food-grade surfactants and its antibacterial applications

255th National Meeting (2018)

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