Effect of storage and drying the phenolic content of a new destoned cake from virgin olive oil production

In the last decades the phenolic compounds of the extra virgin olive oil (EVOO) have been associated with protection against oxidative damage and particularly of the cardiovascular system. Recently EFSA has recognized these properties allowing to insert a specific claim in the label [1]. Since with the crushing only 2-3% of total phenols is retained in the oil, while the majority is lost with the wastes, the interest towards the by-products of oil mill has increased over the years. This study is focused to investigate on a new waste constituted by a destoned olive cake directly obtained from a biphasic decanter. Recently this by-product has been included into a concentrate-based diet for lamb obtaining an extended meat oxidative stability [2]. This waste contains a mix of typical polyphenols present in the fruit (verbascoside) and also in the extra virgin olive oil (oleuropein aglycone derivatives). Many technological factors can influence the content of these phenolic compounds, and about that the thermal effects of an industrial spray-drying as well as the changes in polyphenols of the fresh olive cake during storage have been evaluated by HPLC/DAD/MS. The phenolic content remains almost unaltered after the spray-drying process obtaining, through the use of maltodextrins, a fine non hygroscopic powder. Moreover, the three months of storage at room temperature in closed tank, induced a strong reduction of the content of oleuropein derivatives and an increment of tyrosol and hydroxytyrosol. Fermentation processes were not observed after storage as confirmed by the unaltered smell of the waste. These results indicate this by-product as an interesting natural source of phenolic compounds, mainly verbascoside, hydroxytyrosol, and secoiridoids (oleuropein aglycone derivatives) typical of the EVOO. The product seem to be suitable to use as food antioxidant or ingredient in nutraceutical products