UV–visible spectral changes of gamma irradiated olive leaves extract

Abstract

Olive leaves benefits are less well known, despite having potential health benefits that could make them a valuable addition to a daily diet, compared to olive oil, which is well known for the many benefits it provides. The antioxidant capacity of olive leaves extract (OLE) is higher than that of the most known powerful antioxidants, such as vitamins C and E or pure hydroxytyrosol. The aim of this study was first to maximize the bioactive compounds in extra virgin olive oil (EVOO) by enriching it with olive leaves; the EVOO acts as an extraction solvent, and a study of the macerating period was carried out to select the best macerating period to improve the stabilization of the bioactive compounds in the olive oil matrix. Once the best macerating period was selected (7 days), OLE was gamma-irradiated with a dose of 25 kGy to assess its oxidative stability. To this end, UV–visible spectroscopy was used to perform stability and quality analysis of the OLE during a macerating period of 21 days and after irradiation. The results of this study show an extremely significant (p < 0.0001) improvement in the quality parameters (K232, K270, and ΔK) and in total carotenoids and chlorophylls, assessed by K470 and K670, among all the macerating periods of OLE compared to the control group. Regarding the irradiated OLE compared to the irradiated EVOO, there was an extremely significant (p < 0.0001) difference in ΔK. In addition, there was a significant decrease in total carotenoids and chlorophylls in the irradiated EVOO compared to the irradiated OLE. In conclusion, olive leaves extract in olive oil could be used as a free radical scavenger in food irradiation and tissue sterilization to alleviate the detrimental effects of ionizing radiation.