Studies on Mycoflora and Aflatoxin in regular and Decaffeinated Black Tea

The mycofloral analysis of twenty different kinds of black tea powder (commonly used in Egypt) indicated that, all these samples have wide range of mould species and counts. A thirty two species and 2 varieties belonging to 9 genera were collected on 1% glucose- (7 genera and 20 species) and 40% sucrose- (7 and 23+2 varieties) Czapek's agar at 28°C. The most prevalent mould on one or two substrates were members of Aspergillus, Penicillum, Cladosporium and Eurotium. The most polluted tea, in total count, were Tayseer, Blue Tea Pot and El-Balabel. The lowest contaminated tea were Khan El-Khallily, Yaquot and El-Arosa.
The total count of tea-borne fungi was more flourished by increasing moisture content. Aspergillus flavus and A. tamarii represent the most prevalent moulds after 20 days of tea storage at 45% m.c. Aflatoxin production by A. flavus IMI 89717 was also increased by the increase of moisture content of both regular and decaffeinated tea. Aflatoxin biosynthesis on decaffeinated tea was more hazardous than the regular tea specially at 45% m.c.
Aflatoxin biosynthesis of A. flavus IMI 89717 was recorded in all kinds of tea after 20 day of storage at 45% m.c. and 28°C. The highest aflatoxin quantity produced in Al-Fares, Ezi-Nasser, Lipton and Tayseer tea, and by their isolates of A. flavus in PD broth. The lowest quantity produced on Khan El-Khallily and Massgeed tea, and by their isolates in liquid medium.