Predictive model for growth of ochratoxigenic strains of Aspergillus carbonarius isolated from Argentinean dried vine fruits

ANDREA PATRIARCA; STELLA MARIS ROMERO; VIRGINIA FERNÁNDEZ PINTO; GRACIELA VAAMONDE

Villa Carlos Paz, Córdoba, Argentina

Conferencia; Myco-Globe Argentina 2006 Conference - "Advances in research on toxigenic fungi and mycotoxins in South America ensuring food and feed safety in a myco-globe context"; 2006

Universidad Nacional de Río Cuarto

Predictive Model For Growth Of Ochratoxigenic Strains Of Aspergillus Carbonarius Isolated From Argentinean Dried Vine Fruits   Authors: ANDREA R. PATRIARCA, STELLA M. ROMERO, VIRGINIA E. FERNANDEZ PINTO, GRACIELA VAAMONDE.   Affiliations: Laboratorio de Microbiología de Alimentos, Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Ciudad Universitaria, Pabellón II, 3º Piso, Buenos Aires, Argentina. E-mail: andreap@qo.fcen.uba.ar.       Aspergillus carbonarius is an ochratoxin A (OTA) producing fungus, predominantly responsible for the production of this mycotoxin in grapes, wine and dried vine fruits. The objective of this study was to determine the in vitro effects of water activity (aw, 0.80-0.95) and temperature (15-35ºC) on lag phase extension and radial growth rate of a cocktail inoculum of four strains of A. carbonarius isolated from Argentinean dried vine fruits. The maximum growth rate was observed at 0.95 aw and 30ºC (17.46 mm day-1). In general, growth rates increased with the increment of aw. No growth was observed at aw below 0.85. Optimum temperature for growth was 30ºC for all aw levels tested. At 15ºC growth only occurred at the higher aw levels evaluated (0.925 and 0.95) at a growth rate of 3.82 and 5.57 mm day-1 respectively. The shortest lag phase (0.26 days) was found at 0.925 aw and 35ºC. At marginal conditions of aw and temperature the lag phases increased, being the highest registered at 20ºC and 0.89 aw (33.7 days). Two different predictive models were used to fit the growth data and were statistically evaluated. A growth rate model based on the Gibson aw relationship and a quadratic relationship with temperature showed the best performance and goodness of fit. Lag phases were modelled by a polynomial equation which yielded a very good fit of the data-set. Both growth rate and lag phase models were validated by comparison with experimental results and data from the literature. Predictive models of lag phases prior to mycelial growth and growth rates under the influence of aw and temperature might be used to determine safe storage life of foods.