Abstract
•Methods for optimal recovery of anthocyanins from corn pericarp were developed.•Anthocyanin recoveries increased with increase in extraction stages.•Techno-economic viability of anthocyanin and ethanol coproduction was evaluated.•Anthocyanin-ethanol coproduction had higher profitability than dry grind process.•Anthocyanins can be produced as a high value coproduct in corn dry grind process.
High anthocyanin concentration in the pericarp, and bioethanol coproduction from remaining fractions make purple corn an attractive source for anthocyanin extraction. Water-based anthocyanin recovery would provide ‘natural’ anthocyanin extract with diverse applications in food industry. However, low anthocyanin recovery with water-based extraction is not economically feasible on a commercial scale. The objective of this study was to investigate various approaches for increasing water-based anthocyanin recovery from purple corn and assessing techno-economic feasibility of these process options for commercial scale application. Anthocyanin recoveries of 48.6, 68.6, 77.9 and 66.8 % with single-stage, two-stage, three-stage, and two-stage countercurrent water-based extractions, respectively, from pericarp, were higher than recoveries (30.8 %) with process conditions used in previous studies. Single-stage extraction with corn flour had 46.1 % higher anthocyanin yield than single-stage extraction with pericarp due to low pericarp yields. Annual ethanol and anthocyanin yields for plants processing 1113 MT purple corn/day were between 35.2 and 36.3 million gal and 496 and 795 MT, respectively for processes modified for water-based anthocyanin extraction, compared to 42 million gal for the conventional process. Capital costs for modified processes ($97.4–101.4 million) were higher than the conventional process ($87.2 million). Due to the high value of anthocyanins, ethanol production costs for modified processes ($0.98 to 0.48/gal) were lower than the conventional process ($1.34/gal). Internal rate of return for modified technologies was 1.9–3.1 times that of the conventional process, indicating an improvement in economic performance. Anthocyanin extraction process with three-stage anthocyanin recovery had the highest profitability among the processes.