Modeling aflatoxin B1 production by Aspergillus flavus during wheat malting for craft beer as a function of grains steeping degree, temperature and time of germination.

This study aimed to model the aflatoxin B1 (AFB1) production by A. flavus in wheat grains during malting for craft beer. A total of sixty-four different combinations of grains steeping degree (ST; 41, 43, 45 and 47%), temperature (13, 15, 17 and 19 °C) and time of germination (48, 72, 96 and 120 h), comprising the range of malting conditions that allow the production of quality malt, were assayed. AFB1 was produced in a range of 15.78 ± 3.54 µg/kg (41% ST, 13 °C for 48 h) to 284.66 ± 44.34 µg/kg (47% ST, 19 °C for 120 h). The regression model showing an acceptable fit to the experimental data (adjusted R2 0.84) for AFB1 as a function of grains steeping degree, temperature and time of germination. Results showed that AFB1 levels in wheat malt increase with increase of the temperature or time of germination. Within the range of tested malting conditions, no significant effects were observed for steeping degree on AFB1 levels in wheat malt. The generated model is useful to estimate the AFB1 levels in wheat malt. Findings highlight overall that if wheat grains are contaminated with A. flavus, AFB1 might be produced in malt in levels above the limits set by regulatory agencies, regardless the steeping conditions used.

Fungal communities in rice cultivated in different Brazilian agroclimatic zones: From field to market.

Rice is one of the most consumed cereals in Brazil and around the world. Due to the major health impact of rice consumption on populations, studies about its quality have great importance. The present study determined the mycobiota of soil, field, processing and market rice samples from two production systems in Brazil, dryland in the state of Maranhão and wetland in the state of Rio Grande do Sul. These areas are distinct agroclimatic zones. A total of 171 rice and 23 soil samples were analyzed. A high differentiation was observed in the composition of the fungal communities found in the two production systems, as the wetland presented greater fungal incidence and biodiversity. It was observed that toxigenic species from Aspergillus section Flavi and Fusarium, present in the field, may infect rice grains pre or postharvest and may persist into the final product.

Occurrence of Aspergillus section Flavi and aflatoxins in Brazilian rice: From field to market.

The guarantee of the high quality of rice is of utmost importance because any toxic contaminant may affect consumer health, especially in countries such as Brazil where rice is part of the daily diet. A total of 187 rice samples, from field, processing and market from two different production systems, wetland from the state of Rio Grande do Sul, dryland, from the state of Maranhão and market samples from the state of São Paulo, were analyzed for fungi belonging to Aspergillus section Flavi and the presence of aflatoxins. Twenty-three soil samples from wetland and dryland were also analyzed. A total of 383 Aspergillus section Flavi strains were isolated from rice and soil samples. Using a polyphasic approach, with phenotypic (morphology and extrolite profiles) and molecular data (beta-tubulin gene sequences), five species were identified: A. flavus, A. caelatus, A. novoparasiticus, A. arachidicola and A. pseudocaelatus. This is the first report of these last three species from rice and rice plantation soil. Only seven (17%) of the A. flavus isolates produced type B aflatoxins, but 95% produced kojic acid and 69% cyclopiazonic acid. Less than 14% of the rice samples were contaminated with aflatoxins, but two of the market samples were well above the maximum tolerable limit (5µg/kg), established by the Brazilian National Health Surveillance Agency.

Kinetics of aflatoxin degradation during peanut roasting.

This study investigated aflatoxin degradation during peanut roasting. First, peanuts contaminated with three initial aflatoxin concentrations (35, 332 and 695µg/kg) were roasted at 180°C for up to 20min. The percentage of aflatoxin degradation after 20min were 55, 64 and 81% for peanuts contaminated with aflatoxin at 35, 332 and 695µg/kg, respectively. This difference was statistically significant (p<0.05), showing that initial concentration influences aflatoxin reduction. Thereafter, peanut samples contaminated with an initial aflatoxin concentration of 85µg/kg were roasted at 160, 180 and 200°C for 5, 10, 15, 20 and 25min, then residual concentrations of aflatoxin were determined. Roasting at 160, 180 and 200°C resulted in an aflatoxin reduction of 61.6, 83.6 and 89.7%, respectively. This study has provided quantitative data reinforcing the fact that roasting alone is not enough to control aflatoxins in peanuts.