Isolation and identification of fungi producing Ochratoxin in coffee bean varieties available in the markets of Wadi Ataba

Abstract

Coffee is one of the most commonly consumed beverages worldwide، and in Libya، the demandfor coffee has significantly increased. This study focused on isolating fungi that may grow on coffee beans، with an emphasis on mycotoxin-producing fungi such as Aspergillus. Four samples of roasted coffee beans were collected from the local market in the Wadi Atba municipality of Libya. The results indicated that the contamination of the samples with fungi was high، both before and after treatment with a chlorine solution at concentrations of 0.2% and 0.6%. Although the washing process reduced the fungal count، mycotoxin-producing fungi were still present.

Nine fungal strains were isolated from the samples and were identified morphologically as A. ochraceus، A. parasiticus، A. flavus، A. carbonarius، A. niger، Mucor، Rhizopus، Cladosporium، and A. terreus. Some chemical tests were conducted to understand their relationship with contamination and fungal growth in coffee beans. Potato dextrose agar، followed by yeast extract agar and dextrin agar، proved to be the best culture media for isolating fungi present in the samples.

The strains suspected of producing mycotoxins were tested based on their morphological characteristics and colony color using filter paper saturated with a 20% ammonia solution. The results showed that they produced aflatoxins and ochratoxin، as evidenced by the change in color of the ammonia-saturated filter paper to an orange-red hue.