EFFECT OF FOLIAR FERTILIZATION FOR OLIVE TREES ON THE BIOACTIVE COMPOUNDS, PURITY AND ORGANOLEPTIC ATTRIBUTES OF OLIVE OILS

Abstract

this investigation was carried out during two seasons 2014 and 2015 at farm located EL -Nobarya, EL-Behera governorate, Egypt, to study the influence of foliar fertilization with solution of potassium and magnesium sulphate at ratios of 3 and 5% and 0.5 and 1.5%, respectively, on the organolyptic attributes, purity, overall quality index, stability, bioactive compounds (tocopherols, pigments, polyphenols and diortho phenols) and phenolic compounds of Koronaki olive oil under the environmental condition. The results were as follows: the spraying with potassium and magnesium sulphate at ratios of 5% and 1.5% foliar fertilization, respectively, gave the highest positive attribute (fruity) of olive oil, followed by 3 and 0.5%, respectively compared with the control samples in seasons 2014 and 2015, while the defect properties of olive oil were equal to zero in both treated (foliar fertilized) and untreated (control) samples during two seasons under study. Results showed that the lowest parameters for K232 and K270 nm. of olive oil were obtained when olive trees were foliar fertilization by potassium and magnesium sulphate at different concentrations in two seasons compared with control samples, while Δk recorded slight increase as a result of all previous treatments. Oleuropein, ellagic and E-vanillic phenolic compounds recorded high content compared to other phenolic compounds in the control samples while ellagic compound decreased compared with the control samples during two seasons.. Commonly, most phenolic compounds increased as a result of allfolair fertilization under study. Foliar fertilization with a solution of potassium and magnesium sulphate at all concentrations caused a high increment in Epi-catechin and cinamic compounds in season 2015, whilst these compounds decreased in seasons 2014 compared to control samples. But it caused a decrease in carotonoids content in two seasons and also in chlorophylls content in season 2014 only. On the other hand, it caused an increase in total tocopherol in two seasons with a higher value (5%) for foliar fertilization. Therefore, folair fertilization by potassium and magnesium sulphate at different concentrations caused increment in di-o-phenols of olive oil compared to the control samples during two seasons