Water Activity and Temperature Effects on Fungal Growth and Ochratoxin A Production by Ochratoxigenic Aspergillus carbonarius Isolated from Tunisian Grapes |
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| Authors: | Salma Lasram Souheib Oueslati Ana Valero Sonia Marin Abdelwahed Ghorbel Vicente Sanchis |
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| Affiliation: | Authors Lasram, Oueslati, and Ghorbel are with Laboratory of Molecular Physiology of Grapevine, Borj-Cedria Biotechnology Center, B.P. 901 Hammam-Lif, 2050 Tunisia. Authors Valero, Marin, and Sanchis are with Food Technology Dept., CeRTA-UTPV, Univ. of Lleida, Av. Alcalde Rovira Roure 191, 25198 Lleida, Spain. Direct inquiries to author Lasram (E-mail: ls_salma@yahoo.fr). |
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| Abstract: | ABSTRACT: This study investigated the effects of temperature (15 to 37 °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 °C. At 37 °C, the growth rate decreased significantly (P < 0.05). Maximum toxin production occurred at temperatures in the range of 15 to 25 °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. |
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| Keywords: | A. carbonarius growth ochratoxin A temperature water activity |
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