Sustainable β-carotene production from sorghum syrup using Rhodotorula glutinis: bioprocess optimization and scale-up

Abstract

β-Carotene, a key provitamin A carotenoid, is widely used as an antioxidant and natural pigment. Due to animals' inability to synthesize carotenoids, dietary sources are essential. This study utilized low-cost sorghum syrup for β-carotene production via Rhodotorula glutinis fermentation. Bioprocess optimization using response surface methodology was conducted in shake flasks, then scaled to 300 mL and 7 L fermentations. The optimized medium (9.18% sorghum syrup, 0.96% yeast extract, 0.07% KH₂PO4, 0.13% (NH4)₂SO4, 0.42% MgSO4) yielded a predicted 1003 µg/g β-carotene after 10 days. Scale-up achieved 1153 µg/g (300 mL) and 1753.33 µg/g (7 L). Nutritional analysis showed the presence of chelated minerals, vitamins, proteins, and glucosamine, enhancing biomass value. These results highlight sorghum syrup as an effective, sustainable substrate for β-carotene production with applications in food, feed, and nutraceutical sectors. One Sentence Summary: Using sorghum syrup as a low-cost substrate, we optimized β-carotene production by Rhodotorula glutinis via response surface methodology and validated at 7 L scale (up to 1,753 μg/g), while profiling the nutrient-dense biomass (protein, minerals, glucosamine) for food/feed applications.