EFFECT OF WATER ACTIVITY AND TEMPERATURE ON TENUAZONIC ACID PRODUCTION BY ALTERNARIA-ALTERNATA ON SUNFLOWER SEEDS

Alternaria alternata is isolated in high frequency in sunflower seeds both in the field and storage. This species produces several toxic met abolites among them alternariol, alternariol monomethyl ether and tenu azonic acid. The accumulation of mycotoxins is regulated by physical, chemical and biological factors and for their production in many commo dities nothing is known with regards to these conditions. In sunflower seeds the optimal conditions of temperature and water activity for te nuazonic acid production are unknown. The aim of this work was to inve stigate the effect of temperature and water activity on tenuazonic aci d production by Alternaria alternata ITEM 539 in sunflower seeds. The temperature conditions evaluated were: 20, 25, and 30 degrees C and th e water activities were 0.97, 0.90, 0.87, 0.80. The tenuazonic acid de terminations were carried out during the incubation period at interval s of 7 days. Under conditions of constant temperature 25 degrees C) an d variable water activities, 0.90 was the optimal value for tenuazonic acid production. At this water activity of the optimal temperature fo r tenuazonic acid production was 25 degrees C.