CHEMICAL AND NUTRITIONAL EVALUATION OF OLIVE LEAVES AND SELECTION THE OPTIMUM CONDITIONS FOR EXTRACTION THEIR PHENOLIC COMPOUNDS

Abstract

This work was carried out to evaluate some chemical and nutritionalproperties of olive leavesOlea europaea L. Cv. Kalamata, and investigate theoptimum conditions for extraction their total phenolic compounds. Chemical composition and minerals content of whole and boiled leaves weredetermined. Amino acids profile of olive leaves was also estimated. Phenoliccompounds were extracted from the leaves using different solvents anddifferent extraction times. The obtained results revealed that slight variationswere observed between the whole and boiled olive leaves regarding their contents of crude protein, ether extract and ash contents that amounted inwhole leaves 10.6, 7.9 and 6.8%, while in boiled leaves were 10.7, 8.1 and6.7%, respectively. Olive leaves are a rich source of crude fiber and minerals.Calcium was the predominant element of whole and boiled olive leavesfollowed by potassium. Olive leaves are a good source of iron whichamounted 19.1 and 19.5 mg/100g for whole and boiled olive leaves,respectively. Olive leaves contain all essential amino acids (exceptethionine) in favorable amounts and the total percentage was 57.51g/100gprotein and lysine was the major essential amino acid (17.12%) followed byleucine (8.82%). Computed protein efficiency ratio and computed biologicalvalue of olive leaves protein were higher than those of casein. 70% ethanolfor 8 hrs and boiled water (90oC) for 10 min gave the highest amount of totalphenolic compounds (38.8 and 39.2 mg galic acid equivalent/g, respectively).There was no certain correlation between increasing of time and the amountof phenolic compounds recovered from olive leaves.