Aspergillus carbonarius growth and ochratoxin A production in irradiated dried grapes under different water activity and temperature conditions.

ASTORECA A; BARBERIS C; MAGNOLI C; DALCERO A

World Mycotoxin Journal

Wangenigen Academic Publishers

Año: 2010 vol. 3 p. 175 - 182

1875-0710

Aspergillus carbonarius growth and ochratoxin A production in irradiated dried grapes under different water activity and temperature conditions. A.L. Astoreca 1,2*, C.L. Barberis 1,2, C.E. Magnoli 1,3, A.M. Dalcero 1,3 1 Departamento de Microbiología e Inmunología. Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto. 2 Fellowship of Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina. 3 Member of Consejo Nacional de Investigaciones Científicas y Tecnológicas (CIC-CONICET), Argentina. Running headline: Ecophysiology of Aspergillus carbonarius in dried grapes Abstract Grapes are products which have different destinations. The most important in the national and international market is the wine production but other destination of the grapes is their dehydration to elaborate the dried grapes. Dried vine fruits are at greater risk of ochratoxin A (OTA) contamination than wine grapes because the ratio of Aspergillus carbonarius to A. niger aggregate increases during drying. Growth of these species and consequently OTA production can be influenced by different environmental factors, being the two most important the water activity (aW) and temperature. Therefore, the determination of the optimal environmental conditions is essential for finished food and raw materials safety. The objectives of the present work were to evaluate the lag phase, growth rate and OTA production by two A. carbonarius strains on irradiated dried grapes at different aW (0.910, 0.928, 0.955, 0.973 and 0.995), temperature (15, 25 and 30ºC) and incubation times (7, 14 and 21 days) . No significant differences between the growth rates reached by both strains at 25ºC and 30ºC were observed. These experiments showed the marked influence of aW and temperature on OTA production in irradiated dried grapes. This study suggest that fungal growth could be prevented by an adequate control of environmental factors which are important in the development of A. carbonarius species on this and others substrates destined to human consumption.