Establishment of a stable Amaranthus tricolor callus line for production of food colorant

This study aimed at demonstrating the effects of fermentation time (24, 48, 72, 96, and 120 h) and water activity (0.943, 0.970, and 0.985) on the production of cellulolytic enzymes by solid-state fermentation of purple mombin (Spondias purpurea L.) residue using Aspergillus niger. The fermentation was carried out at 35°C and the enzyme production was measured as endoglucanase and total cellulose activities. The optimum condition for endoglucanase was water activity 0.974 and 93.8 h of fermentation, reaching a production of 3.21 U/g of residue; whereas for total cellulase it was 0.958 and 79.4 h achieving 12.1 U/g of residue. Fermentation time had a greater effect on the endoglucanase activity, while water activity had a more significant influence on the total cellulase activity. Endoglucanase had optimum activity at temperature of 50°C and pH 5.0. Although cellulase total optimum activity was also at pH 5.0, the maximum activity was at 60°C.