Evolution of antioxidant compounds in lime residues during drying

This work aimed at studying the effects of pretreatment, namely, hot water blanching, and hot air-drying (60–120 °C) on the evolutions of vitamin C, phenolic compounds, nomilin and limonin, which are potential bioactive compounds in lime residues during drying. Blanching was found to decrease both the antioxidant contents and activities of the residues due to thermal degradation and loss with the blanched water. During drying, nomilin and limonin contents first increased, probably due to the remaining enzyme activity after blanching. After this period, the amounts of both nomilin and limonin dropped rapidly, due to thermal degradation. Product temperature was found to be a major factor controlling the changes of limonoids and there was no direct correlation between the moisture change during drying and limonoid contents. During degradation of vitamin C and phenolic compounds, the amounts of both substances decreased as the product temperature increased and the moisture content decreased during drying. The amount of phenolic compounds correlated well with the total antioxidant activity and phenolic compounds were found to be a major contributor to antioxidant activity of the product.