Barberries (Berberis vulgaris) species have different nutritional and phytochemical content and valuable health-promoting properties (Bakmohamadpor, Javadi, Azadmard-Damirchi, & Jafarizadeh-Malmiri, 2021). Barberry contains flavonoids, polyphenols, anthocyanins, vitamins, and pigments (Naji-Tabasi, Emadzadeh, Shahidi-Noghabi, Abbaspour, & Akbari, 2021b). Berberis vulgaris is rich in anthocyanins which are polyhydroxy and polymethoxy glycosides and are derivatives of 2-phenylbenzopyrylium or flavylium cation (Bakmohamadpor et al., 2021). Anthocyanins are glycosylated anthocyanidins; sugars are attached to the 3-hydroxyl position of the anthocyanidin (sometimes to the 5 or 7 positions of flavynium ion) (Sharifi, Mortazavi, Maskooki, Niakousari, & Elhamirad, 2013). Cyanidin-3-glycoside and pelargonidin-3-glycoside are the main anthocyanins in barberry. Berberis vulgaris L. fruits are used for ailments and discomforts of kidneys, urinary and gastrointestinal tract, liver diseases, bronchial discomforts, and as a stimulant for the circulatory system (Naji-Tabasi, Emadzadeh, Shahidi-Noghabi, Abbaspour, & Akbari, 2021a; Sarraf, Beig-babaei, & Naji-Tabasi, 2021).
Barberry extracts prepared using advanced extraction methods have demonstrated antioxidant, antidiabetic, anti-inflammatory, anticancer, anti-melanogenic, anticholinergic, antipsychotic, and antimalarial activities (Aliakbarlu, Ghiasi, & Bazargani-Gilani, 2018; Qadir et al., 2009). Berberis amurensis alkaloids (jatrolysine, palmatine, berberine) have also shown anticancer properties (Wu et al., 2015). In addition, barberry (Berberis vulgaris) root extract has demonstrated cosmetic potential (Dulić, Ciganović, Vujić, & Zovko Končić, 2019). Berberis species phytochemicals are widely used in various pharmaceuticals and dietary supplements (Belwal, Pandey, Bhatt, & Rawal, 2020). Indeed, they are used in the food industry as food additives, flavorings, and preservatives (e.g., to improve the stability of oils and lipids) (Ardestani, Sahari, & Barzegar, 2015; Belwal, Bhatt, Rawal, & Pande, 2017; Tavakoli, Sahari, & Barzegar, 2017), nutritional supplements, and topical products for dermatology (Ali Redha, Siddiqui, & Ibrahim, 2021; Dulić et al., 2019). It is, therefore, essential to use the best processing methods to preserve the nutritional and functional potential of barberry and the species in general.
In extraction, variables like technique, time, size, solvent, pH, concentration, volume, and ratio can be optimized. Traditional methods can be simple but ineffective due to heat-sensitive bioactive compounds breaking down. (Azimi Mahalleh, Sharayei, & Azarpazhooh, 2020). Conventional extraction processes are also associated with a high solvent requirement and low mass transfer (Najafpour Darzi, Heidari, Mohammadi, & Moghadamnia, 2019). These extraction methods are labor-intensive, often expensive, and environmentally unfriendly. Therefore, there is a need for more sustainable alternative extraction techniques (Kumari et al., 2019), such as ultrasound, pulsed electric field, supercritical fluid extraction, and pressurized liquid, which are also known as non-thermal or green technologies (Soquetta, Terra, & Bastos, 2018). On the other hand, the application of new extraction technologies such as ultrasonic, microwave, ultrasonic-microwave, pulsed electric field, homogenate, and high hydrostatic pressure assisted extraction can improve the yield and efficiency of extraction.
Classical solvent extraction methods, and modern extraction methods, including supercritical carbon dioxide, pulsed electric field, high voltage electric discharge process, ultrasonic, microwave, subcritical water, and enzymatic methods, were used to extract effective compounds from Berberis vulgaris (Maroun et al., 2018).
Extraction using a pulsed electric field is a non-thermal extraction technique in which the electric field penetrates the cell wall and permeabilizes the cell membrane, causing leakage of intracellular compounds (Carullo, Pataro, Donsì, & Ferrari, 2020). This is due to a phenomenon called electroporation, where a strong electric field permeabilizes the cell membrane, allowing ions and macromolecules to exit the cell (Juan M. Martínez, Delso, Álvarez, & Raso, 2020). The parameters such as field strength, temperature, extraction time, and specific energy are factors that affect the efficiency of this extraction method (Juan M. Martínez et al., 2020).
Plasma with relatively low ionization used to scrape plant tissue and extract its active substances is called cold plasma (Keshavarzi, Najafi, Ahmadi Gavlighi, Seyfi, & Ghomi, 2020). Another innovative but largely unexplored approach in the extraction process can offer cold plasma applications if the appropriate conditions (input voltage, gas, and treatment time) are applied to reduce the treatment time (Muhammad et al., 2018). So, these methods are much quicker than conventional methods.
Enzymatic extraction is a promising alternative method that requires fewer solvents and short extraction times. It can also increase the yield of active ingredients (Chávez-González et al., 2020). Furthermore, extractions of plant anthocyanins and vacuolar pigments with solvents often do not reach completion as the solvent is only sometimes fully distributed in the substrate (Cagliari et al., 2011; Mushtaq, Sultana, Bhatti, & Asghar, 2015). Pectinases are a class of enzymes that catalyze the degradation of substances contained in pectin, primarily including pectinesterase and depolymerase. The former cleaves the ester bond of pectin to produce pectic acid, while the latter cleaves the glycosidic bond of pectic acid (Chen et al., 2023).
This study used vacuum plasma, pulsed electric field, and enzymatic pre-treatment method (using pectinase enzyme) to increase extraction efficiency. The reason for applying plasma and pulsed electric field pre-treatments is to increase efficiency, reduce energy consumption and decrease extraction time. The purpose of this research was to focus on the distinct color compounds of this plant, which are anthocyanins, and try to increase its extraction efficiency through the methods mentioned above. In this study, the response surface methodology (RSM) based on a central composite face-centered design (CCD) was used to optimize the extraction of anthocyanins and polyphenols from barberry.