Temperature and pH levels: Key factors effecting hidden/free zearalenone during maize processing.

The productions of food, agricultural products and feed involve a variety processing conditions, which can affect the release/binding of zearalenone (ZEN) with macro-components in maize, resulting in the interconversion of hidden ZEN with free ZEN. This interconversion can cause the uncertainties and individual differences in the exposure assessment. To fully overcome this uncertainties of the potential risks for humans and animals, further research regarding the key factors and rule of interconversion is needed. This study was designed to analyze the key factors that can induce the interconversion of hidden ZEN with free ZEN during maize processing. Results showed the conversion of hidden ZEN into free ZEN during thermal and alkaline processing, while it showed the conversion of free ZEN into hidden ZEN during acid processing. Furthermore, the temperature and pH-induced interconversion rules were also applicable to the practical maize processing (tortilla production). During producing tortilla, when the processing conditions of 4% lime, cooking time (60 min) and cooking temperature (100 °C) were set, the tortilla products with the lower hidden ZEN hazard could be obtained. This study presented new insights into the risk assessment of maize products as the conversion between hidden ZEN and free ZEN during processing.