Improving technical and economic feasibility of water based anthocyanin recovery from purple corn using staged extraction approach

Abstract

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.