Aflatoxin production at different relative humidities on gamma-irradiated herbs used as Egyptian drinks

The effect of gamma radiation on some herbs used as drinks in Egypt indicated that doses between 20 and 40 KGy are capable for mold inhibition on tea, anise, fenugreek and liquorice. The minimum relative humidity [RH] for aflatoxin production and growth of Aspergillus flavus on tea and two strains of Aspergillus parasiticus on anise and liquorice was found to be 90%. The minimum water activity [aw] for aflatoxins production and growth of local Aspergillus parasiticus and Aspergillus parasiticus NRRL 3145 on malt extract broth was 0.9 and 0.85, respectively

effect of the water activity of the growth medium on pesticide sensitivity in saccharomyces cerevisiae and S rouxii

Yeast cells of Saccharomyces cerevisiae and the osmotolerant yeast S. rouxii were grown aerobically and anaerobically on media the water activity of which was regulated either by sodium chloride or glycerol. The yeast cells were washed and suspened either in isotonic solutions of either solutes or in distilled water. Cells were then exposed to three pesticides namely the fungicide Antracol, the insecticide Supracide, and the akaricide Akar. Results were expressed as D-values [Decimal death time i.e, time in minutes required to kill 90% of cells]. Results showed that Supracide exerted the higest toxicity on both yeasts, followed by Akar, while Antraclo was the least toxic. Also, cells of S. cerevisiae showed higher response to the water activity of the growth medium in relation to pesticide sensitivity over S. rouxii in presence of either sodium chloride or glycerol