Browsing by Author "Lopez-Alarcon, Camilo"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    EVALUATION OF THE TOTAL AMOUNT OF PHENOL GROUPS IN COMPLEX MIXTURES BY FOLIN'S AND ORAC-FLUORESCEIN METHODOLOGIES
    (2013) Maria Campos, Ana; Lopez-Alarcon, Camilo; Lissi, Eduardo
    The total number of phenolic HO groups in a mixture and their average reactivity are fundamental parameters in the evaluation of the capacity of the sample to remove potentially damaging free radicals. The total number of phenolic groups is generally determined by Folin's method and several competitive experiments have been proposed to estimate the reactivity of the sample. Among those stand the Oxygen Radical Absorbance Capacity (ORAC) methodologies. However, when fluorescein is employed as target molecule (ORAC-FL methodology) the index is more related to the number of phenolic groups than to their average reactivity. In the present work it is shown that both indexes correlate with the number of phenolic groups in pure compounds and with the total number of reactive OH groups in complex mixtures (beverages, infusions, fruits and vegetables). This leads to a fair correlation between Folin's and ORAC-FL indexes in these samples.
  • No Thumbnail Available
    Item
    Immobilization of Andean berry (Vaccinium meridionale) polyphenols on nanocellulose isolated from banana residues: A natural food additive with antioxidant properties
    (2019) Felipe Alzate-Arbelaez, Andres; Dorta, Eva; Lopez-Alarcon, Camilo; Cortes, Farid B.; Rojano, Benjamin A.
    Nanocellulose obtained from banana rachis (NCBR) was loaded (through simple impregnation) with a polyphenolic-rich extract (PRE) of Andean berries (Vaccinium meridionale). The adsorption/desorption of polyphenols onto NCBR and the thermal stability and antioxidant activity of the polyphenolic-NCBR nanocomplex (NCX) was studied. Thermodynamic properties (Delta H-ads degrees, Delta S (ads)degrees, and Delta G(ads)degrees) showed that polyphenols interact with NCBR by physisorption through a spontaneous and exothermic process. The NCX kept the original color of PRE (magenta) and released polyphenols in aqueous medium (80% of phenolic compounds in the first hour and 50% of anthocyanins in the first few minutes). The NCX showed high antioxidant activity, as evidenced by traditional assays, and inhibited the peroxyl radicals mediated oxidation of a tryptophan-containing peptide. Additionally, NCX inhibited lipid peroxidation in an emulsified system of Sacha inchi oil exposed to accelerated oxidative conditions. In conclusion, the NCX showed good properties as an antioxidant with potential use as a food additive.