Zanoni et al. (1999) have registered an increase in HMF content in dried tomatoes once with the increase in temperature and drying duration. The increase of drying duration from 390 to 430 min led to the increase of HMF content from 10 to 36mg/kg DM at temperature of 80oC and from 18 to 512mg/kg DM at 110oC. The paper shows that if the HMF content is greater than 20 mg/kg DM, it will change the colour from red to brown.