MYCOTOXIN POLLUTION IN STORED CORN GRAINS

Abstract

Corn is one of the major dietary crops in Egypt for man and animal. It is used in food technology in several purposes. Moulds in stored grains cause deterioration in grain quality and viability. In addition it has hazardous side effects due to mycotoxins produced in grains.

Occurring fungi were surveyed on corn grams obtained from different sources. Isolated fungi were Fusarium spp., Aspergillus spp., Helmintho5porium spp., Alternaria spp. and Penicillium spp. Pathogenicity tests showed that Fusaria were more detected and were differed in virulence expressed as percent grain germination and seedling blight.

Mycotoxins were detected in com grains naturally polluted with different moulds. Certain species of Fusarium were examined for capability to produce toxins on rice and maize meals in vitro. Fusaria differed in produced toxin types and quantity. Zearalenone, Deoxynivalenol, Diacetoxyscirpenol and T-2 Toxin • were evaluated qualitatively and quantitatively.

Grain rot development and mycotoxin production by F culmorum were examined under conditions of temperature and relative humidity. Twenty five °C and 80% relative humidity, respectively were optimum for rot development and toxin production. Gradual increase in temperature caused increase in Fusarium, Aspergillus and Penicillium grain rots which were further developed by prolonged storage period.

Prolonged storage decreased grams total carbohydrate contents. However, total soluble sugars, reducing sugars and protein contents were increased.

Natural plant oils and certain fungicides were used to control F culmorum in vitro. Eugenol and citrus oil were effective. Sodium chloride at high concentration was remarkably suppressive to fungal growth. The fungicides Benlate 50%, Topsin 70, Vitavax Thiram 75%, Rizolex 50% and Dithane M 45 were fungistatic and/or fungitoxic to F culmorum.