Bioaccessibility of carotenoids from transgenic provitamin A biofortified sorghum

Biofortified sorghum (Sorghum bicolor (L.) Moench) lines are being developed to target vitamin A deficiency in Sub-Saharan Africa, but the delivery of provitamin A carotenoids from such diverse germplasms has not been evaluated. The purpose of this study was to screen vectors and independent transgenic events for the bioaccessibility of provitamin A carotenoids using an in vitro digestion model. The germplasm background and transgenic sorghum contained 1.0-1.5 and 3.3-14.0 μg/g β-carotene equivalents on a dry weight basis (DW), respectively. Test porridges made from milled transgenic sorghum contained up to 250 μg of β-carotene equivalents per 100 g of porridge on a fresh weight basis (FW). Micellarization efficiency of all-trans-β-carotene was lower (p < 0.05) from transgenic sorghum (1-5%) than from null/nontransgenic sorghum (6-11%) but not different between vector constructs. Carotenoid bioaccessibility was significantly improved (p < 0.05) by increasing the amount of coformulated lipid in test porridges from 5% w/w to 10% w/w. Transgenic sorghum event Homo188-A contained the greatest bioaccessible β-carotene content, with a 4-8-fold increase from null/nontransgenic sorghum. While the bioavailability and bioconversion of provitamin A carotenoids from these grains must be confirmed in vivo, these data support the notion that biofortification of sorghum can enhance total and bioaccessible provitamin A carotenoid levels.