Bench-scale processing of red-colored extracts from sunflower hulls

Extracts were prepared from the hulls of purple-hulled sunflower, then processed using clarification, evaporation, and spray drying. Addition of citric acid to solvent or raw extract substantially reduced pigment yield, probably by precipitation, but the loss was diminished if citric acid addition was delayed until after evaporation or spray drying. The highest overall yield, 1.5 to 1.7 mg spray-dried pigment per gram of dry hulls, was achieved without addition of citric acid. Pigment loss was observed at each step, and in the case of evaporation, appeared to result mainly from pigment degradation. Although increased browning was observed at each step, reconstituted spray-dried extracts still had an attractive red color.