Salma Lasram

Multi-mycotoxin determination in cereals and derived products marketed in Tunisia using ultra-high performance liquid chromatography coupled to triple quadrupole mass spectrometry.

The aim of the study was the use of a fast and simple method using ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) for the simultaneous determination of aflatoxins (AFB1, AFB2, AFG1 and AFG2), ochratoxin A (OTA), fumonisins (FB1 and FB2), deoxynivalenol (DON), T2 and HT2 toxins in 58 samples of raw wheat (n = 34), barley (n = 5), sorghum (n = 3), processed wheat (n = 13) and breakfast cereals (n = 3) from Tunisian markets. The frequency of contamination of total samples with the analyzed mycotoxins was 50%. AFG2 was the most frequently detected in 11 samples (4 wheat, 4 barley and 3 sorghum) and it was detected at 5.2-52.4 μg/kg. HT2 toxin contaminated seven samples (4 wheat and 3 barley) and it was detected at 5.0-11.1 μg/kg. FB2 was detected in one wheat, sorghum, semolina and breakfast cereal samples at 5.0-61.5 μg/kg. FB1 was detected in three samples (2 sorghum and one barley) at 6.4-120 μg/kg. AFB1 was only found in two sorghum samples at 14 and 79.9 μg/kg. OTA was detected in one sorghum sample at concentrations below limit of quantification (5 μg/kg). The analytical results also showed that all the analyzed samples were not contaminated with DON, AFG1, AFB2 and T2 toxin.

Water Activity and Temperature Effects on Fungal Growth and Ochratoxin A Production by Ochratoxigenic Aspergillus carbonarius Isolated from Tunisian Grapes

This study investigated the effects of temperature (15 to 37 degrees C) and water activity (0.90 to 0.99) on the growth and production of ochratoxin A (OTA) by Aspergillus carbonarius cultured on synthetic nutrient medium (SNM) after 5 and 10 d of incubation. Total of 8 ochratoxigenic A. carbonarius, isolated from vineyards located in different regions of Tunisia, were used. Growth data were modeled by the flexible model of Baranyi and growth rates at each set of conditions were obtained. For both growth and OTA production, optimal water activity was 0.99; however, optimal temperature varied. The optimal temperature for growth was 30 degrees C. At 37 degrees C, the growth rate decreased significantly (P < 0.05). Maximum toxin production occurred at temperatures in the range of 15 to 25 degrees C with the optimum one depending on the isolate tested. Significant amounts of OTA were produced after only 5 d of incubation. Our results showed that A. carbonarius isolated from Tunisian grapes behave as those from European and Australian grapes, as reported in the literature, although some differences in trends for growth and OTA production were observed.

Alternating temperatures and photoperiod effects on fungal growth and Ochratoxin A production by Aspergillus carbonarius isolated from Tunisian grapes

The effect of three alternating temperatures cycles (20/30, 20/37 and 25/42 degrees C) and photoperiod on growth and Ochratoxin A (OTA) production of six isolates of Aspergillus carbonarius on synthetic nutrient medium were investigated. The different temperature regimes affected significantly both the mycelial growth and the OTA production. The best growth and OTA production were recorded at 20/30 degrees C. The isolates from the region of Baddar produced the highest OTA yields. A 24 h light cycle generally enhanced the growth of A. carbonarius. Growth rates cycles of 11 h/13 h light/darkness and 24 h darkness were often similar for individual isolates, such conditions enhanced OTA production in two of the six isolates tested.