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Browsing by Author "Marcet, Ismael"

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  • Biosynthesis of antioxidant xanthan gum by Xanthomonas campestris using substrates added with moist olive pomace
    Publication . Crugeira, Pedro Jorge Louro; Almeida, Heloísa H.S.; Marcet, Ismael; Rendueles, Manuel; Pires, Marcella Golini; Rafael, Helder Martins; Rodrigues, Ana Isabel G.; Santamaria-Echart, Arantzazu; Rafael, Helder; Barreiro, M.F.; Golini Pires, Marcella
    Moist olive pomace (MOP) is a high moisture content by-product of the olive oil industry. Managing this recalcitrant residue (transport, storage, and drying) is a priority demanding investment in finding alternative valorisation routes. In this context, the biosynthesis of xanthan gum (XG) incorporating MOP in the substrate (0.0 %, 5.0 %, 10.0 %, 15.0 %, 20.0 %, 25.0 %, 30.0 % and 50.0 %) to induce bacterial stress was attempted. XG biosynthesis yield was quantified, and the product was characterised by structural analysis (FTIR), thermal behaviour (TG), rheology and antioxidant capacity. Relative to the control (sample with no added MOP), a significant increase in XG biosynthesis was found for concentrations up to 30.0 % MOP. In particular, for XG produced with 15 % MOP, a 50.91 % (p < 0.0001) increase was achieved, together with 395.78 % for viscosity. In general, XG produced with MOP presence showed antioxidant activity, a value-added property, especially for applications in the food, pharmaceutical and cosmetic areas. The results indicated that the stress imposed by the MOP induced a microbial response leading to XG production increase, structural and viscosity modifications, and antioxidant properties incorporation. Overall, this work points out a new MOP application contributing to the sustainability of the olive oil productive chain from a biobased circular economy perspective.
    2023Journal article Open access Show more
  • Solid dispersions as effective curcumin vehicles to obtain k-carrageenan functional films for olive oil preservation
    Publication . Rezende, Stephany; Santamaria-Echart, Arantzazu; Almeida, Heloísa H.S.; Marcet, Ismael; Carpintero, Maria; Rendueles, Manuel; Lopretti, Mary; Dias, Madalena M.; Barreiro, M.F.
    Synthetic packaging materials offer cost efficiency and performance but pose environmental risks. This study explores sustainable alternatives by developing k-carrageenan (KC) films functionalized with curcumin, using solid dispersions (SDs) to improve curcumin's compatibility, addressing the challenge of incorporating hydrophobic functionalities into hydrophilic film matrices. Films with varying curcumin content (1–20 wt%; KC1- KC20) were compared to a base film without curcumin (KC0) regarding water solubility, vapor permeability, water contact angle, and tensile properties. Compared to KC0, KC10 (10 % curcumin-SDs) exhibited improved water resistance, with solubility decreasing from 82.89 % to 77.18 %, while maintaining vapor permeability (2.96 × 10􀀀 10 g⋅m/s⋅m2⋅Pa). KC10 demonstrated enhanced tensile properties, with a 12.51 % increase in tensile modulus (241.47 MPa), a 3.86 % increase in stress at break (3.50 MPa), and a 4.42 % increase in strain at break (2.36 %). Furthermore, it exhibited potent antioxidant activity without releasing curcumin into a simulated fatty medium (non-migratory active protection mechanism), effectively preserving olive oil by limiting lipid oxidation to a peroxide value (PV) of 14 mEq. O2/kg oil, compared to 20 mEq. O2/kg oil in unprotected samples under accelerated conditions. It demonstrated significant antimicrobial activity with bacterial reductions of 95.4 % (Escherichia coli) and 90.6 % (Listeria monocytogenes), surpassing KC0. In conclusion, k-carrageenan films functionalized with curcumin SDs are promising and sustainable alternatives to synthetic packaging materials.
    2025Journal article Open access Show more