Ochratoxin A production by Aspergillus westerdijkiae in Italian-type salami

Abstract

The occurrence of ochratoxin A (OTA) in matured meat products can be attributed to mycotoxin coming from raw materials and/or molds that develop on the product surface during ripening. This work aimed to evaluate OTA production by Aspergillus westerdijkiae inoculated on the surface of sausages and its diffusion into the product throughout ripening, study the effect of relative humidity (RH) on the production of this mycotoxin, and investigate the presence of OTA in dry fermented sausages that naturally present intense contamination by A. westerdijkiae. Italian-type sausages were surface inoculated with A. westerdijkiae and two distinct experiments were performed. In the first, the sausages were matured in a chamber with decreasing RH (from 95 to 75%) for 35 days. In the other, the sausages were incubated under different RH (79, 85 or 95%) for 21 days. Samples were taken at the beginning of the experiments and every 7 days, subdividing into casing, outer border, and core for analyses. Sausage samples naturally spoiled by ochratoxigenic fungi were collected during sanitary inspection. Even in the presence of A. westerdijkiae mycelia, no OTA was detected for up to 7 days of sausage maturation. On the other hand, this study demonstrated that the growth of A. westerdijkiae on salami surface produces high amounts of OTA on the casing and allows its diffusion through the casing with contamination to the outer border of sausages. In the same way, it shows that under similar water activity values of substrate, RH influences the amount of OTA produced. Conversely, OTA was restricted to the casing in the naturally contaminated sausages.