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- Study of antioxidant and antitumoral activity of cork processing wastewaters components fractionated by ultrafiltration membranesPublication . Gomes, Luís; Borges, C.; Serralheiro, M.L.M.; Pacheco, Rita; Minhalma, MiguelCork processing wastewater present a severe environmental problem due to its high content in organic matter, such as sugars and non-biodegradable compounds like polyphenols (PPs), namely tannins. In this work, the assessment of the biological activity and identification of valuable polyphenolic compounds was envisaged. These compounds were obtained using membrane technology, leading to the valorisation of the wastewater components and simultaneously leading to the decrease of its pollutant content.
- Nanofiltration of Cork Wastewaters and Their Possible Use in Leather Industry as Tanning AgentsPublication . Geraldes, V.; Minhalma, Miguel; de Pinho, M. N.; Anil, A.; Ozgunay, H.; Bitlisli, B. O.; Sari, O.Cork processing wastewater is a very complex mixture of vegetal extracts and has, among other natural compounds, a very high content of phenolic/tannic colloidal matter that is responsible for severe environmental problems. In the present work, the concentration of this wastewater by nanofiltration was investigated with the aim of producing a cork tannin concentrate to be utilized in tanning. Permeation results showed that the permeate fluxes are controlled by both osmotic pressure and fouling/gel layer phenomena, leading to a rapid decrease of permeate fluxes with the concentration factor. The rejection coefficients to organic matter were higher than 95%, indicating that nanofiltration has a very good ability to concentrate the tannins and produce a permeate stream depleted from organic matter. The cork tannin concentrate obtained by nanofiltration and evaporation had total solids concentration of 34.8 g/l. The skins tanned by this concentrate were effectively converted to leather with a shrinking temperature of 7 degrees C.
- Cork processing wastewaters components fractioned by ultrafiltration membranes–studies of antioxidant and antitumoral activityPublication . Gomes, Luís; Borges, Carlos; Serralheiro, Maria Luisa; Minhalma, Miguel; Pacheco, RitaBACKGROUND: Cork processing wastewater is an environmental problem due to its high content of organic matter, such as sugars and non-biodegradable compounds such as polyphenols (PPs), namely tannins. Membrane technology aimed at valorisation of the wastewaters components, concentrate stream, and simultaneously offer a pre-treatment of the wastewater, permeate stream. In this work, the identification of bioactive PPs was also envisaged. Several fractions of cork processing wastewaters were generated using two cellulose acetate ultrafiltration membranes of 3 kDa and 74 kDa for PPs isolation according to nature and molecular weights. The membranes were prepared by the phase inversion method and fractionation was made in concentration and diafiltration modes. The wastewater and the fractions were analyzed in terms of total organic carbon, total phenols, tannins and total polysaccharides content and the compounds present were identified by FTIR, LC–MS and quantified by HPLC-DAD. RESULTS: Compounds such as quinic, gallic, protocatechuic, brevifolin carboxylic and ellagic acids were identified as the major compounds in cork wastewater. The wastewater and the fractions were tested for antioxidant activity and for capacity to inhibit the proliferation of the growth of human breast carcinoma cell lines, MCF-7. The fractions revealed high antioxidant activity with EC 50 values ranging from 1.174 ± 0.069 to 1.943 ± 0.179 mg/mgDPPH. The fractions demonstrated to be efficient as cell proliferation inhibitors, with values of IC50 ranging from 0.20 ± 0.003 to 0.46 ± 0.02 mg mL-1. CONCLUSION: The process reported demonstrates that PPs compounds can be recovered from cork effluent and further reused as high-value bioactive compounds.