Peanut skin phenolics obtained by green solvent extraction: Characterization and antioxidant activity in pure chia oil and chia oil in water (O/W) emulsion

BACKGROUND: The peanut skin (PS) is considered as an industrial waste with undervalued applications. Although several studies report potent antioxidant capacities of PS phenolics, the effectiveness in highly unsaturated lipid systems has not yet been evaluated. The objectives of the present study were two-fold: (i) to characterize a PS phenolic extract (PSE) obtained by means of a green technology and (ii) to evaluate its antioxidant efficacy on pure chia oil and chia oil in water (O/W) acid emulsion. RESULTS: PSE was composed mainly of monomeric and condensed flavonoids (procyanidin and proanthocyanidin oligomers). PSE displayed strong antioxidant properties as measured by different reducing power and radical scavenging capacities [IC50 = 0.36 μg dry extract (DE) mL−1 for ferric reducing antioxidant power; IC50 = 4.96 μg DE mL−1 for 2,2-diphenyl-1-picrylhydrazyl (DPPH)•; IC50 = 6.01 μg DE mL−1 for 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS)•+; IC50 = 2.62 μg DE mL−1 for HO•]. It also showed high antioxidant efficacy when tested in pure chia oil under accelerated oxidation conditions (Rancimat, 100 °C). When added to the O/W emulsions maintained at 40 °C for 15 days, the PSE was more effective than a synthetic antioxidant (tert-butylhydroquinone) with respect to minimizing the formation and degradation of lipid hydroperoxides. CONCLUSIONS: The antioxidant efficacy of PSE was primarily attributed to the abundance of compounds with a high number of phenolic-OH groups. Because they were found to cover a relatively wide range of partition coefficients, the antioxidant properties could be also enhanced by effect of both interfacial and solubility phenomena. All of these features allow the potential use of PSE as a natural antioxidant in different types of foods, including acid emulsion systems.Fil: Bodoira, Romina Mariana. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; ArgentinaFil: Martinez, Marcela Lilian. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Velez, Alexis. Universidad Nacional de Córdoba; Argentina. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Cittadini, María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Ribotta, Pablo Daniel. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; ArgentinaFil: Maestri, Damian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin