Antifungal synergic activity of essential olive oil and alcoholic turmeric extracts against isolates from the dried grapes raisins

Abstract

Fungi are responsible for a wide variety of harm to humans, including food spoilage and infections. Using chemicals to restrict fungal development or infections has negative repercussions, such as human health dangers from the chemical applications and rising antifungal-drug resistance, so this study aimed to use medicinal plants and their extracts as an alternative method to restrict fungal growth. Ten isolates of the genus Aspergillus were identified from the fruits of dried grapes (raisins) of all kinds (Iraqi black raisins, Iranian yellow raisins, and brown raisins) at the species level using three – differential media: Czapek Yeast Extract Agar( CYA), Malt Extract Agar( MEA), and 25% Glycerol nitrate agar (G25N) incubated in 5, 25 and 37 ºC. Aspergillus niger was the most common isolated species. The number of A. niger isolates reached seven from all types of dried grapes, while A. flavus recorded three isolates from black raisins and brown raisins. Aspergillus Flavus Parasiticus Agar (AFPA) was used to detect the ability of A. flavus isolates to produce aflatoxin at 25-30 ºC for one week. Alcoholic extract of turmeric showed a significant inhibitory effect on the colony diameter of both A. flavus and A. niger isolated from the fruit of Iraqi black raisins with an inhibition rate of 86.6% and 68.8 %, respectively, at 4 mg/ ml concentration. The mixture of turmeric and essential olive oil gave a distinct inhibitory effect, reaching a 100% inhibition rate from the lowest to highest concentration for both A. niger and A. flavus .