Chemical compounds issued from two plants grown in Lebanon: Origanum Syriacum and Cymbopogon Wimterianus have been employed for a wide range of applications such as food preservation purpose, and insecticidal activity. This study aim to evaluate and exam the composition of extracts, powder and oil of these plants in order to use them as potential food preservatives in flat bread, and the evaluation of their essential oils as potential insecticides on granary weevils found in bread. The preliminary phytochemical screening results showed that the aqueous and ethanolic extracts of oregano and citronella are rich in secondary metabolites. Furthermore, the hydro-distillation of Syrian oregano and Java citronella leaves resulted in essential oil extraction yields of 4.3% OEO and 0.75% JCEO. Syrian oregano ethanolic extracts contained 110.674 mg GAE/g plant powder of total phenols and 52571.429 μg RE/g plant powder of total flavonoids. The results shows that the powders of Syrian oregano and Java citronella showed promising food preservative effects. These findings were supported by a decrease in the moisture content of the bread samples and most importantly illustrated by a significant decrease in fungal growth in samples fortified with concentrations of 1.5% oregano powder and 2% citronella and oregano powder mix. Finally, these two plants showed positive insecticidal activity optimal when using OEO and JCEO mixed with a 7% LD50, on grain weevils.
Key words: Oregano, Citronella, Food preservative, Insecticide, Moisture