Transforming olive pits into functional foods: evaluation of phenolic, antioxidant, nutritional and microbiological properties

Background: The research aims to propose a new potential role for the olive pits as new functional foods for supporting human nutrition, health and wellbeing. The experimental research has been focused on developing a new method to suitably process the by-products of table olives (olive pits) and investigating the health-related and nutritional components of the final products.Methods: A new methodology of processing the olive pit by-product to successfully resume the edible part of the pit interior, has been developed (as showed below): In the final form of the processed olive pit, a detailed identification and determination of specific phenolic compounds with pharmacological interest was developed with a high-performance liquid chromatography- photodiode array detector (HPLC-DAD). Antioxidant activity was also evaluated with DPPH free radical scavenging assay. Other health-related nutritional parameters were also investigated, with an emphasis on fatty acid profile analysis, dietary fiber and protein concentration. Microbiological quality of the final products were also investigated. Results: Results showed that in the processed form of the olive pits, total bioactive phenolic content was found in significant levels, reaching an 8-25-fold higher concentration than the usual phenolic content of extra virgin olive oil. The quantitative determination showed that the principal biophenol determined was hydroxytyrosol, followed by tyrosol. DPPH analysis presented a high antioxidant activity, whilst the product presented considerable contents of monosaturated fatty acids, especially oleic acid, plant proteins and dietary fibers. Microbiological quality of the product was efficient in all samples tested. Conclusions: After suitable processing, the by-products of the olive pits can be considered as a valuable source of bioactive phenolic compounds with strong antioxidant activity,  as well as a good source of monosaturated fatty acids, oleic acid, plant proteins and dietary fibers. Overall, the olive pits could be reconsidered as a functional food or matrix with a promising potential for pharmaceutical, nutritional and cosmetic applications.Keywords: olives; pits; phenols; antioxidants; monosaturated fatty acids; oleic acid; functional foods; by-products