Potencial use of antioxidants for control of growth of Aspergillus carbonarius and Aspergillus aculeatus on peanut-based media.

CARLA BARBERIS; ASILI R.; ASTORECA A.; MAGNOLI C.; DALCERO A.

Carlos Paz, Córdoba

Congreso; “Integration of mycotoxin and toxigenic fungi MYCO-GLOBE Research for Food Safety in Global System”; 2006

Peanut (Arachis hypogaea L.) is an economically important crop commodity in Argentina. Its annual production reaches 350 million tons, 98% of this production is found in the center of the Province of Córdoba (SAGyP, 2005). Peanut is colonized by a number of toxigenic fungal species. The greatest significant mycotoxins for peanuts are produced by Aspergillus spp; including aflatoxins and ochratoxin A (OTA). A. niger is one of the most frequently isolated agregates in agricultural products associated with OTA production from regions with warm and tropical climate. The detection and control of these ochratoxigenic species and OTA in agricultural raw material, has become important to evaluate the risk of contamination and prevention of entry into the human and animal food chain (Keshri et al.,2000). Recent in vitro studies showed that the growth of Fusarium verticilloides and F. proliferatum on culture media could be controlled by food grade antioxidants (Etcheverry et al., 2002; Torres et al., 2003). There is no avaible information of antioxidants and Aspergillus section Nigri species interaction on peanut meal extract agar (PMEA).The aim of this study was to evaluate the effect of butylated hydroxianisole (BHA) and propylparaben (PP) on the lag phase prior to growth and growth rate by strains of  A. carbonarius and A. aculeatus under different water activity (aw) and temperature conditions.  A. carbonarius (ANM 4) and A. aculeatus (ANM 123) were used.  The antioxidants BHA and PP  were added  at 1,5,10 and 20 mM at 45-50 ºC; The aw of the basic media was adjusted to 0.995, 0.98 and 0.93 with glicerol. The plates were centrally needle-inoculated and  incubated for 30 days at 18 and 25 ºC. All treatments were repeated four times. Two diameters were obtained fron each colony. Radial growth rates (mm/day) were calculated as the slope of the linear regression obtained from plotting the colony radius of the replicates against  time. In the control treatments there was an increase in the lag phase and a growth decrease as aw and temperature decreased. The antioxidants  showed  a further increase in the lag phases prior to growth  at  higher concentrations. In both temperatures, changes in aw slightly reduced growth at 0.98 aw and approximately 50% at a 0.93 aw when compared  with controls. At all aw levels, BHA at 20mM and PP at 5 mM completely inhibited growth. At 1mM and 0.995 or 0.98 aw, the antioxidants were relatively ineffective, and the growth increased at 0.93 aw when compared with controls.  In all treatments PP was more effective than BHA. The information obtained  shows that the antioxidants BHA and PP could be considered as effective fungitoxicants for Aspergillus section Nigri species and helpful to prevent their growth in storage peanut.