Optimization of Celery Seed Essential Oil Extraction and its Antioxidant Activity Using Response Surface Methodology and Ultrasound-Assisted

Medicinal plants contain antioxidant compounds are benefits to human health and celery as a medicinal plant, is rich in antioxidant. Celery (Apiumgraveolens L.) seed has a lot of essential oil (EO) and this EOs has long been used for fragrance industries, spice, pharmacological and cure diseases. EO for celery seeds is 1.5-3% (v/w). Although a number of methods are applied for the acquisition of essential oils, the most frequently used method is steam distillation. Among EO extraction methods, ultrasound-assisted extraction (UAE) is an inexpensive, simple, and efficient extraction technique. This is most likely due to the intensification of mass transport and to the facilitation of solvent penetration into plant tissues which are damaged by the ultrasounds. Response surface methodology (RSM) is a powerful mathematical model with a collection of statistical techniques where in, interactions between multiple process variables can be identified with fewer experimental trials. It is widely used to examine and optimize the operational variables for experiment designing, model developing and factors and condition optimization. Antioxidants deactivate free radicals before they can damage to the bimolecular cells structure. In the present study, to find effective antioxidant constitutes of EO, antioxidant activity were determined using DPPH scavenging assay and FRAP methods.
In this research, the effect of seed to water ratio (X1), ultrasonic time (X2), and extraction time (X3) on essential oil extraction (v/w) from wild celery seeds were evaluated by the following equations. Antioxidant activity ofEO was measured via two methods of FRAP, and %DPPH30min.
%EO (v/w) = 1.200000 0.075000 X1 -0.300000X2 0.875000X3 0.725000X12 – 0.825000X22 0.725000X32 0.300000X1X2 – 0.150000X1X3 0.300000X2X3
%DPPH30min = 60.4136 6.3782 X1 -22.7935X2 3.7569X3 – 8.0662X12 – 45.5443X22 – 13.5193X32- 6.6459X1X2 – 5.8430X1X3 21.7333X2X3
FRAP (µMFe�µl EO) = 1432.94 166.65 X1 166.22X2 126.29X3 – 384.48X12 – 1215.25X22 – 322.43X32- 87.85X1X2 575.35X1X3 – 219.80X2X3
For optimization of EO extraction conditions, the RSM method was used. A Box–Behnken design (BBD) with three center points was used to study the effects of three independent variables, water to seed ratio (X1), ultrasonic time (X2), and extraction time (X3) on three dependent responses (EO, %DPPH30min, and FRAP). The independent variables were transformed to three levels (−1, 0, 1), and the complete design consisted of 15 experimental runs with three replications of the center points. The following quadratic polynomial model was fitted to the predicted responses of EO, %DPPH30min, and FRAP with changing water to seed ratio (X1 = 375, 500, and 625 ml water to 35g seed); ultrasonic time (X2= 10, 20, and 30 min); and extraction time (X3=1, 2, and 3 h) in extraction samples; Where EO, %DPPH30min, and FRAP stands (Yn) for the predicted responses for X1–X3; b0 is the constant coefficient; b1, b2, and b3 are the linear coefficients; b11, b22, and b33 are the quadratic coefficients; and b12, b13, and b23 are the cross-coefficients. The accuracy of the estimated coefficient was analyzed by ANOVA method and the model accuracy was obtained using the F test at 1 and 5 % by indicating coefficient R2. Yn = b0
According to the results, the best ratio of treatments (optimized condition) was 35g seed to 625 ml water ratio, ultrasonic time of 20 min, and extraction time of 3h. At this optimization conditions, the ratio of 35g seed/625 ml water, non-using ultrasonic, and extraction time of 3h was used as a control treatment. Under optimized condition, the highest essential oil percentage (v/w) and antioxidant activity with styles of FRAP, and %DPPH30min was obtained 2.33% (v/w), 1513.6µMFe�µl EO and 48.52%, respectively. However, at the control treatment, the highest essential oil percentage (v/w) and antioxidant activity with styles of FRAP, and %DPPH30minwas revealed at 1.45 % (v/w), 1064µMFe�µl EO and 29.30%, respectively. In the study of optimization of ultrasound-assisted extraction of anthocyanins from mulberry, using response surface methodology and also, optimization of ultrasonic-assisted extraction of pomegranate seed oil were shown similarity results.
The values of adjusted R-squared (0.9972, 0.9598, 0.9472) for the equation are reasonably close to 1, indicated a high degree of correlation between the observed and predicted values. Therefore, the experimental values were agreed with those predicted by RSM models, and it suggested that using RSM method foroptimization of extraction condition is suitable. Furthermore, application of ultrasonic technology increased essential oil extraction and its antioxidant activity. In addition, results indicated that the UAE method is a powerful tool for the extraction essential oil from seeds.