Impact of the malaxation temperature on the phenolic profile of cv. Cobrançosa olive oils and assessment of the related health claim

Phenolic compounds contribute to the bioactive properties of olive oil. However, olive oils can only support a health claim concerning the protection against oxidative stress depending on the polyphenolic concentration, requiring effective measures during extraction to preserve/enhance their concentrations. The effect of the malaxation temperature (22, 28 and 34 °C) on the phenolic profile was studied for industrially extracted cv. Cobrançosa oils. Higher malaxation temperatures decreased the contents of the majority of the chromatographically detected compounds (P<0.05, one-way ANOVA), enabling oils differentiation. This decreasing trend was observed for hydroxytyrosol and tyrosol bound forms, determinant for the health claim, which were also negatively affected by temperature, despite revealing that all the industrially extracted oils tested supported the health claim. The observed constant free to bound forms ratio showed that the temperature range tested had a minor effect on bound-forms hydrolysis, being both free and bound forms equally affected by temperature.The authors are grateful to the Foundation for Science andTechnology (FCT, Portugal) forfinancial support by national fundsFCT/MCTES to CIMO (UIDB/00690/2020), to CEB (UIDB/04469/2020), to REQUIMTE-LAQV (UIDB/50006/2020) and to BioTecNorteoperation (NORTE‐01‐0145‐FEDER‐000004) funded by the EuropeanRegional Development Fund under the scope of Norte2020‐Programa Operacional Regional do Norte. Ítala Marx acknowledges the Ph.D.research grant (SFRH/BD/137283/2018) provided by FCT. NunoRodrigues thanks the National funding by FCT- Foundation for Scienceand Technology, P.I., through the institutional scientific employment program-contract.info:eu-repo/semantics/publishedVersio

Estimating hydroxytyrosol-tyrosol derivatives amounts in cv. Cobrançosa olive oils based on the electronic tongue analysis of olive paste extracts

The estimation of hydroxytyrosol-tyrosol derivatives amounts in olive oils through the analysis of olive pastes collected during malaxation is of utmost relevance due to the relationship with the oils' health claim regarding the protection of blood lipids from oxidative stress. Olive pastes were collected during the industrial extraction of cv. Cobrançosa oils (060 min; 2234 °C). Total phenolic contents of pastes' extracts were assessed (28005400 mg GAE/kg paste). Oils were laboratory-extracted from each paste and, after acid hydrolysis, the contents of hydroxytyrosol and tyrosol derivatives as their sum were determined (25135, 62120 and 68255 mg/kg oil). Olive paste extracts were analyzed with a lab-made potentiometric electronic tongue. The device enabled estimating the total phenolic contents of the pastes (internal-validation: correlation coefficient  0.86, root mean square error  392 mg GAE/kg). Moreover, the electronic tongue allowed a more satisfactory indirect estimation of the total secoiridoids derivatives amounts of the oils (internal-validation: correlation coefficient  0.91, root mean square error  25 mg/kg), based on the olive pastes' potentiometric profiles, without requiring the oils posteriori invasive/destructive analysis. Thus, the electronic tongue could be foreseen as a potential tool for anticipating the health claim fulfilment during oils industrial extraction.The authors are grateful to the Foundation for Science and Tech nology (FCT, Portugal) for financial support by national funds FCT/ MCTES to CIMO (UIDB/00690/2020), to CEB (UIDB/04469/2020), to REQUIMTE-LAQV (UIDB/50006/2020) and to BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. ´Itala Marx acknowledges the Ph.D. research grant (SFRH/BD/137283/2018) provided by FCT. Nuno Rodrigues thanks the National funding by FCT- Foundation for Science and Tech nology, P.I., through the institutional scientific employment program contract.info:eu-repo/semantics/publishedVersio