| With the improvement of living standard,people pay more and more attention to food safety and health problems,the development of a natural,green,pollution-free natural preservative has attracted the attention of consumers.Korean pine needles contain pine needle essential oil,and the main components of this oil are terpenes,Among them,Terpene,Caryophyllene and Cubebene have strong antibacterial activity.The essential oils of Korean pine needles in Yichun area were extracted by ultrasound-assisted steam distillation and supercritical CO2 extraction.The optimal process conditions were optimized and determined,and the antibacterial activity of the pine needle needle oil was studied to provide reference for the development and utilization of the pine needle needle oil.The main findings are as follows:（1）The optimum extraction conditions of Korean pine needle oil through ultrasonic assisted steam distillation（UASD）were obtained by single factor and response surface experiments.The optimal extraction conditions of UASD method:the ratio of material to liquid is 1:10,the distillation time is 5 h,the ultrasonic power is 260 W,the yield of pine needle essential oil is 0.42±0.01%,and the relative content of terpene is 64.14±0.74%;UASD method were analyzed by GC-MS,31 compounds were identified;（2）The optimum extraction conditions of Korean pine needle oil through supercritical CO2 extraction（SCF-CO2）were obtained by single factor and response surface experiments.The optimal extraction conditions of SCF-CO2 method:extraction pressure is 12 MPa,extraction temperature is 44℃,extraction time is 1.7 h,the yield of pine needle essential oil is1.71±0.09%,and the relative content of terpene is 72.38±1.14%;SCF-CO2 method were analyzed by GC-MS,48 compounds were identified;The terpenes in the two extraction methods are different,mainly because most of the substances extracted by SCF-CO2 method are macromolecular terpenes,aliphatic and unknown substances with high boiling and high volatility.（3）Research on antibacterial activity of pine needle essential oil by the Oxford cup method,the effect of external factors on the antibacterial activity of pine needle essential oil were studied.The results showed that the antibacterial activity of pine needle essential oil extracted by SCF-CO2 method was stronger than that by UASD method.SCF-CO2 method had the inhibited the eight tested bacteria,among which the inhibition of V.parahaemolyticus was the strongest,but the inhibition of E.sakazak was poor.The inhibitory effect of pine needle essential oil is stronger than that of alkaline under acidic conditions.High temperature will make volatile components in terpenes disperse.Ultraviolet irradiation has no effect on the antibacterial activity of pine needle essential oil.Excessive salt and pine needle essential oil have synergistic promoting effect,and the best shelf life is 60 d.（4）The effects of pine needle essential oil on the antibacterial activity of birch juice was studied.The results showed that the concentration of pine needle essential oil at 6.25 mg/mL could keep the birch juice at room temperature for 12 days without deterioration. |
