Statistical analysis of data from pulsed electric field tests to extract polyphenols

During the last decade, pulsed electric field (PEF) treatment was found to be a useful non-thermal and minimally invasive processing method for breakage of cellular tissue. The strong electric field causes electroporation of plant cells, an increase in their permeability and in some cases, disruption of their structural integrity. Because the integrity of the cell membrane is important to the overall quality of the components within the cell, membrane permeabilization is dependent on several factors such as electric field strength (E), pulse duration (PD), number of pulses (N), and pause between pulses (PBP). In this work, design of experiments for PEF assisted extraction of polyphenols from leaf plant tissues will be presented. The disturbance factors E, PD, N, and PBP were varied to find a suitable combination to maximize extraction yield. For this purpose, multivariate techniques have been used for preliminary evaluation of experimental factors as well as for determination of critical conditions (maximum or minimum) of these factors. Central composite, Box-Behnken and Doehlert designs were among the principal response surface methodologies used in experimental design. Furthermore, the Box-Behnken design of experiments was employed to minimize the number of required experiments. Analysis of variance (ANOVA) was used as a statistical method to quantify main disturbances effects. The key finding is that moderate electric field strength has significant effect on the extraction yield. Moreover, results suggested that higher extraction yield could be achieved under moderate electric field strength and longer treatment time (number of pulses and duration of pulses). The outcome of the statistical analysis will be used to develop surface response models that will be used to optimize the settings for the PEF unit in such way that the extraction yield is maximized.