Spray dried powder of lutein-rich supercritical carbon dioxide extract of gamma-irradiated marigold flowers: Process optimization, characterization and food application

A lutein-rich extract from African marigold (Tagetes erecta L.) flowers (packaged-irradiated) obtained by the green technology of supercritical carbon dioxide extraction at 450 bar (4.5 x 10(7) Pa), 80 degrees C after 105 min of extraction time had lutein content of 215.53 +/- 3.75 mg/100 g dry basis (d.b.) and DPPH radical scavenging activity of 0.83 +/- 0.03 mg/mL (IC50 value). This antioxidant-rich extract was microencapsulated by spray drying to improve shelf-stability of lutein. The encapsulation parameters were optimized using a Taguchi L9 orthogonal array design to obtain highest microencapsulation efficiency (ME%) under the experimental conditions. The optimized conditions of spray drying obtained were: spray concentration (%w/w) of 30, wall material composition of maltodextrin:gum Arabic :: 60:40, core (lutein):wall material :: 1:30, sample feed flow rate of 0.90 mL/min (1.5 x 10(-8) m(3)/s), inlet air temperature of 170 degrees C, spray gas flow rate of 742 L/h (2.06 x 10(-4) m(3)/s) and atomization pressure of -60 mbar (-6000 Pa). At these conditions ME(%) was found to be the highest (78.32%) w.r.t. lutein content (1.28 +/- 0.05 mg/g powder). The encapsulate possessing highest ME% exhibited concomitant highest antioxidant activity (IC50 value of 233 +/- 039 mg/mL and FRAP value of 6.16 +/- 130 mM FeSO4 equivalent/g d.b.) vis-a-vis those obtained at other encapsulation conditions. Besides, half-life of the best encapsulate (E-best) was 6.90 times higher than the native extract under ambient storage conditions (23 +/- 2 degrees C, 80% R.H., in the dark). Along with E-best, lutein-rich native extract and pure lutein were characterized by thermogravimetric/differential thermal analysis, X-ray diffraction analyses, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy analyses. E-best was then employed in designing a novel lutein-rich ready-to-serve beverage and its sensory, physicochemical and phytochemical properties were evaluated. (C) 2018 Elsevier B.V. All rights reserved.