Micotoxigenic fungi and ochratoxin a in coffee fruits with prolonged stay on the tree and on the soil in the brazilian cerrado

Abstract

In Brazil, the regions called ‘Cerrado’ in Minas Gerais and Bahia states are expressive coffee producers and stand out for productivity and quality of grain produced. The bloom unevenness of coffee in Brazil leads to fruit with various stages of maturity at the harvest period. As a result, some producers use low quality grains with long soil or plant contact and mix them with those of quality to compose the harvest. The objective of this work was to study coffee fruits with soil contact of up to 90 days evaluating ochratoxin A (OTA) levels, humidity dynamics and water activity in coffee fruits harvested every 30 days. The coffee with prolonged stay on the plant, showed no major variations in humidity and water activity levels during the 120 days studied. However, in coffee with prolonged stay on the soil, after 90 days, the humidity and water activity levels varied dramatically according each region. During this period, the humidity and water activity were 14.15 and 0.74%, 6.64% and 0.63 for the Cerrado Mineiro and Baiano, respectively. Despite the coffee with prolonged stay in the plant having been heavily colonized by Aspergillus ochraceus G. Wilh. (1877),  OTA contamination was not detected, but in coffees with prolonged stay on the soil, high levels of OTA were observed, 49.42 and 30.93 μg.kg ^-1, for the Cerrado Mineiro and Baiano, respectively. There was OTA  production even in the grains with low water activity, indicating how the complexity of the system in the field interferes with the micotoxigenic dynamic fungi growth and consequently in OTA production.