Evidence of antimicrobial activity of date fruits in combination with high intensity ultrasound.

Abstract

Although dates are highly nutritious materials that may support the growth of spoilage and pathogenic organisms, they are typically safe to store at ambient temperature in a warehouse for up to several months. The goal of this research was to better understand the apparent long-term microbial stability of dates and to investigate new means to further enhance their stability. To this purpose, several different extraction methods with different ultrasonic intensity, ratio of date fruit to water and temperature were first used to investigate their effects on microbial count. Secondly, continuous high-intensity ultrasound waves irradiated date and water mixture sterilized by cold manner and then used as a culture media for native micro flora of dates. Antimicrobial activity was evaluated using agar dilution assay. Results indicate the existence of anti-microbial and anti-fungal activity in date components. Furthermore, sonication of dates decreased microbial counts. Results suggest a synergistic effect between ultrasonication and the presence of antimicrobial substances in date syrup leading to an overall reduction in the initial microbial load of the product. On the whole, 85% decrease was observed in susceptible type of fungi known as Gilmaniella.   Key words:  High-intensity ultrasound, microbial count, date syrup, antimicrobials.