Variation of carotenoid bioaccessibility from sorghum and maize through maturation and dry milling

Ellie George Kean, Purdue University

Abstract

Sorghum and maize grains are staple crops for a large portion of the world population and are specifically targeted for carotenoids biofortification strategies. While carotenoids remain a focus of the biofortication effort, limited information exist on carotenoid levels in sorghum and bioavailability of these from maize and sorghum based foods subjected to traditional and commercial processing. Following carotenoid profiling, decorticated and milled sorghum fractions and commercial milled maize fractions were incorporated into model foods [wet cooked porridge, extruded puff, and bread]. Foods were then screened for carotenoid stability and, bioaccessibility was assessed using a three-stage in vitro digestion process. Carotenoid content in developing sorghum was observed to increase between 10 and 30 days after half bloom (DAHB) [6.06 and 28.53 μg of total carotenoids per thousand kernels (TK)], followed by a significant decline from 30 to 50 DAHB, to a final concentration between 2.62 and 15.02 μg/TK total carotenoids. Lutein and zeaxanthin were found to be primary carotenoid species followed by zeinoxanthin, β-cryptoxanthin and α- and β-carotenes. Carotenoid content in sorghum milled fractions ranged from a low of 2.93–5.57mg/kg in un-bagged decorticated flour to 8.38–10.61mg/kg in bagged bran fractions (a 10 to 41% increases from bagging sorghum). Carotenoids from commercial milled maize fractions were found to be generally higher than sorghum ranging from 1.77-6.50 mg/kg in yellow maize bran to 12.04-17.94 mg/kg in yellow maize meal. Micellarization efficiency (bioaccessibility) of carotenoid from sorghum porridge ranged from 63 to 81% indicating that a significant portion of carotenoids from sorghum are available for absorption. Xanthophylls were generally more efficiently micellarized (75%) than carotenes (52%). For maize, xanthophylls micellarization from whole yellow corn meal products was highest in bread (85%) and similar in extruded puff and porridge (46 and 47%). For extruded puffs and breads, β-carotene micellarization was 10-23%, but higher in porridge (40-63%), indicating that wet cooking may positively influence bioaccessibility of apolar carotenes. Overall these results suggest that sorghum and maize-based products are good dietary sources of bioaccessible carotenoids and specific food preparation methods may influence the relative bioaccessibility of individual carotenoid species.

Degree

Ph.D.

Advisors

Ferruzzi, Purdue University.

Subject Area

Food Science

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