Influence of ohmic heating in the composition of extracts from Gracilaria vermiculophylla


Electric field-based technologies for extraction processes have been gaining importance due to sustainability concerns. This work aims to assess the potential of ohmic heating as an efficient and feasible tool for the extraction of different biocompounds from Gracilaria vermiculophylla and its effect on the extracts' composition. Different ratios of water/ethanol (0 to 75% ethanol, v/v) were used to target different families of biocompounds. The ohmic heating-based extraction was performed at 82 degrees C under electric field and frequency of 2-8 V/cm and 25 kHz, respectively. Conventional extractions without the presence of electric field were made keeping a temperature profile identical to the ohmic heating treatments, thus addressing the potential occurrence of electrical (non-thermal) effects. Extraction yields and extracts composition (content in polysaccharides, proteins, phenolic compounds and pigments) were evaluated. Further, as agar is the major commertially exploited compound from Gracilaria spp., the effect of ohmic heating on the extracted agar in terms of yield, carbohydrates' composition, monosaccharides profile, and gelling ability was also envisaged. Overall, significant differences in the extraction of each family of compounds between ohmic and conventional extractions were observed, being more pronounced at the best solvent for each compound (100% water for carbohydrates, 75:25 water/ethanol for proteins, 75:25 and 50:50 water/ethanol for phenolic compounds and 25:75 water/ethanol for pigments). Higher extraction yields were achieved for ohmic heating at 1 h, except for 100% water, probably indicating accelerated extraction kinetics promoted by the presence of electric field effects. Furthermore, the gelling ability of agar and the antioxidant activity were not impaired by the use of moderate electric fields. Therefore, ohmic heating is an interesting alternative, with reduced energy consumption and improved extraction performances, to recover functional ingredients or additives from seaweeds for the food industry.



subject category

Biotechnology & Applied Microbiology


Pereira, SG; Teixeira-Guedes, C; Souza-Matos, G; Maricato, E; Nunes, C; Coimbra, MA; Teixeira, JA; Pereira, RN; Rocha, CMR

our authors


This work was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of project OH2O - PTDC/EQU-EQU/029145/2017 and the strategic funding of UID/BIO/04469/2019 unit, and by the European Fund for Regional Development (FEDER) and COMPETE 2020 - Competitiveness and Internationalization Operational Program under the scope the projects OH2O (POCI-01-0145-FEDER-029145) and VALORMAR - Full valorization of marine resources: potential, technological innovation and new applications (call 10/SI/2016; reference: 24517) . This work was also developed within the scope of the stratigic funding of CICECO-Aveiro Institute of Materials (UIDB/50011/2020 & UIDP/50011/2020) , QOPNA (UID/QUI/00062/2019) and LAQV-REQUIMTE (UIDB/50006/2020) , financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. This work was also funded by national funds (OE) , through FCT, I.P., within the scope of the frame-work contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19.Statement of informed consent, human/animal rights No conflicts, informed consent, or human or animal rights are applicable to this study.

Share this project:

Related Publications

We use cookies for marketing activities and to offer you a better experience. By clicking “Accept Cookies” you agree with our cookie policy. Read about how we use cookies by clicking "Privacy and Cookie Policy".