Browsing by Author "Alimi, Siwar"
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- Quality grade evolution and health claim fulfillment of olive oils under simulated domestic consumption: kinetic modelling and shelf life predictionsPublication . Alimi, Siwar; Peres, António M.; Casal, Susana; Khemakhem, MaissaOlive oil has always played a vital role in the Mediterranean diet, well renowned for its nutritional properties and related health benefits. This is largely attributed to its high concentration of monounsaturated fatty acids and bioactive minor compounds, such as polyphenols. This study aimed to assess how typical household consumption conditions influence the physicochemical and sensory properties of extra virgin olive oil (EVOO), as well as its compliance with the European Union (EU) health claim. The results of the analysis of ten bottles stored in darkness and exposed to light under simulated household conditions, demonstrated an increase in PV and extinction coefficients over the 9-week period, with a more pronounced rise in the light-exposed samples. In these samples, PV increased by 81.2%, and at 6 weeks it exceeded the legal EU thresholds for EVOO/VOO classification. In contrast, oils stored in darkness kept all physicochemical parameters within legal limits allowing EVOO or VOO classification, up to or beyond the seventh week, respectively. Also, by the eighth week, sensory analysis revealed the presence of rancid in light-exposed samples, with intensities ranging from 3.6 to 6.1, indicating advanced oxidation and rendering the oil unsuitable for consumption (lampante oil). Kinetic models were developed to predict the shelf life (SL) of commercial grade EVOO under household conditions, applying zero-, first-, and second-order kinetic models for PV, K232, and K268 in both dark and light storage conditions. The models fitted well the experimental data (R-Pearson values ranging from 0.89 to 0.97), with PV emerging as the most sensitive SL indicator under these conditions. The estimated SL was approximately 15 days for light-exposed oils and 63 days for oils stored in darkness. The greatest variation in SL predictions, based on PV, K232, or K268, was observed in the light- exposed samples. Photo-oxidation led to a rapid increase in PV, in contrast to the slower rise in extinction coefficients, which are associated with secondary oxidation products that form when oxygen availability diminishes. Regarding the health claim, the content of hydroxytyrosol and tyrosol derivatives remained relatively stable throughout the 9-week period in both dark- and light-stored oils, ranging from 12 to 13 mg/20 g of oil, significantly exceeding the minimum required by the EU regulation. In conclusion, typical household conditions significantly impact the quality of olive oil. Storing olive oil in darkness can extend its SL by 3 to 4 times, compared to light-exposed conditions, in terms of maintaining its EVOO classification.