Studies On Camellia Oil Extraction By Green Solvent Dimethyl Carbonate And Its Thermodynamics And Kinetics

Camellia oleifera Abel, which have a long history of cultivation and utilization for over 2,300 years in china, is an evergreen shrub or small tree in Camellia family. Camellia oil, produced from Camellia oleifera seeds, whose beneficial unsaturated fatty acids are comparable to those of olive oil. In this study, the main components of camellia seed and the physicochemical properties of camellia oil were measured. The technology of camellia oil extraction by green solvent dimethyl carbonate (DMC) was optimized, and its thermodynamics and kinetics were studied for the further development of camellia seed. The main contents are as follows:The main components of camellia seed and the physicochemical properties of camellia oil were measured used GC-MS machine, ultraviolet spectrophotometer and chemical analysis methods. The camellia kernel oil content is 51.27%, which is suitable for camellia oil extraction. The camellia kernel contain 7.12% of crude protein,6.29% of total sugar,12.37% of tea saponin,2.11% of ash,1.06% of crude fiber and 12.4% of water. Except 68.75% of crude fiber, there are 10% of tea saponin,5.31% of water,0.46% of ash,2.57% of crude protein,0.89% of crude fat and 1.26% of sugar in camellia shell. Under the effect of heating and mechanical, the refractive index, saponification value, iodine value, acid value, peroxide value, unsaponifiables content and insoluble impurities content of camellia oil obtained from extraction ultrasonic-assisted are larger than that of camellia oil obtained from extraction by DMC. Camellia oil obtained from extraction by DMC and extraction with ultrasonic-assisted meet the national standard. Fatty acids component and content of camellia oil obtained from different methods are similar, total unsaturated fatty acids’content are about 85%, saturated fatty acids content are about 14%.Methods regarded camellia oil yield as index, used different single-factor experiment designs, the influence of time, temperature, solvent-to-solid ratio on camellia oil obtained from two camellia extraction methods were investigated. The method of response surface based on Box-Behnken central composite design was used to optimize the extraction technolog of the two camellia extraction methods. The optimal technological conditions of extraction by DMC are time of 169 min, temperature of 78℃, solvent-to-solid ratio of 9:1 mL·g-1, the practical camellia oil yield is 90.5%, which is similar to the predicted yield 90%. The optimal technological conditions of extraction with ultrasonic-assisted are time of 84 min, temperature of 75℃, solvent-to-solid ratio of 5:1 mL·g-1, the practical camellia oil yield is 91.69%, which is similar to the predicted yield 91.23%.Analyzed how the camellia oil yield changed with time and investigated the kinetics of camellia oil extraction with green solvent DMC and ultrasonic-assisted. The Kinetic model that included washing and diffusion steps was developed based on the separated variable method and activation energy, enthalpy change, entropy change and Gibbs free energy were calculated. The value of washing step rate constant k1 was 17-37 times of the value of diffusion step rate constant k2. Activation energy values of the two steps were 4.41 and 5.85 kJ·mol-1, respectively. The results indicated that the phenomenological model fitted the experimental data very well. The value of enthalpy change and entropy change were 18.02 kJ·mol-1å'Œ72.20 J·mol-1, respectively. The value of Gibbs free energy obtained from the camellia oil extraction was -4.94 to -7.10 kJ·mol-1. The results indicated that the process was endothermic, irreversible and spontaneous.