AQUEOUS EXTRACTION OF SOLUTES FROM FENNEL (FOENICULUM VULGARE) ASSISTED BY PULSED ELECTRIC FIELD

Abstract

Aqueous nonthermal extraction was performed from thin and coarse fennel gratings of seven different sizes in order to obtain extracts, which could be used as natural food preservatives (antioxidants). A moderate pulsed electric field (PEF) with different intensities, E = 0–600 V/cm, and number of pulses, n = 0–850, was used to electropermeabilize the cell membranes and to accelerate the following extraction. The optimal parameters of PEF were found for each size of grating to maximize the yield of solutes. Extract turbidity and color were evaluated. Additionally, the thermal extraction from coarse gratings was studied at different temperatures (60–90C). The concentration of vitamins C and E in extracts, obtained with thermal and PEF treatments, was estimated. The PEF treatment was more effective for coarse gratings (the juice yield increased from 60 to 98%, and the obtained extracts were less turbid and less colored) than for thin gratings. Furthermore, extracts obtained from coarse gratings treated by PEF contained more vitamins C and E than extracts obtained by thermal extraction. PRACTICAL APPLICATION Researches presented in this article should find their entire practical application in the field of food industries. They will permit preparation of fennel extracts, used as food preservatives (antioxidants), by PEF‐assisted aqueous extraction, which preserves better antioxidant substances. Extracts should be of good quality and the energy consumption should be reasonable.

Applications of Pulsed Electric Field Treatments for the Enhancement of Mass Transfer from Vegetable Tissue

“…Furthermore, extracts obtained from coarse gratings treated by PEF contained more vitamins C and E than extracts obtained by thermal extraction. On the other hand, in order to reach maximum yield, energy required depended on grating size and reached values as high as 40 kJ/kg for largest size [37].…”

“…In addition to the extraction of sugar from sugar beet [38,39,60,74,79,109], PEF has been used to enhance the recovery of soluble substances from apple tissue [59], from carrots [40], and chicory [76], polyphenols and antioxidants from artichoke bracts [22] and from fennel [37], betulin from mushrooms [126], betanine from red beetroot [46,78], and oil from rapeseed [53] and seed maize [54]. Some applications of PEF were also proposed for the recovery of polysaccharides from frog tissue [125] as well as of dissoluble calcium from bones [127].…”

Pulsed Electrical Technologies Assisted Polyphenols Extraction from Agricultural Plants and Bioresources: A Review

“…Initially designed for military or scientific applications of very high energy, HVED can now be adapted for civil applications. They can be classified into three categories: (1) applications in the field of lasers, X-rays and microwaves (mega-joule laser, synchrotron sun, radars, jammers ...) (2) applications for specific test means (lightning tests, electric launchers ...), (3) civil applications processing gases (NOx, SOx, dust smoke ...), liquid handling (removing bacteria, pasteurization, cold extraction of cellular compounds [8][9], flocculation sludge ...), treatment of solid (waste separation and crushing, grinding products, peeling concrete, ceramic sintering ...). This review will focus on the use of this technology for the extraction of polyphenols.…”

Pulse Electric Field-Assisted Extraction

“…PEF treatment was also applied to other tissues, such as red bell pepper and paprika (Ade-Omowaye et al 2001, fennel (El-Belghiti et al 2008), chicory (Loginova et al 2010), alfalfa (Gachovska et al 2006(Gachovska et al , 2009b, and red cabbage (Gachovska et al 2010). Ade-Omowaye et al (2001) studied the impact of PEF treatment at 1.7 kV/ cm on yield and quality parameters (pH, soluble solids [Brix], total dry matter, color, total carotenoids [as β-carotene], and vitamin C) of juice obtained from paprika.…”