Effect of fertilizer on biochemical composition, and antioxidant properties of white‑fleshed sweet potato (Ipomoea batatas L.) flour

This study evaluated the impact of different fertilizer treatments on the proximate composition and antioxidant properties of flour from two white-fleshed sweet potato varieties (PCS and LCCS). The tubers were cultivated in the Sayo district of the Kellem Wollega Zone, Ethiopia. A two-factor experimental design with three blocks was employed, incorporating six treatments: eluate (T1), digestate (T2), compost (T3), a digestate-compost mixture (T4), a negative control (T-), and a positive control with NPK fertilizer (T+), each replicated three times. Analysis of variance (ANOVA) revealed significant differences (p < 0.05) in the biochemical and antioxidant properties of the flours due to both treatment and variety. The PCS variety exhibited the highest ranges for water content (70.09 ± 1.02% to 72.95 ± 2.98%) and lipid content (0.45 ± 0.12 g/100 g to 1.08 ± 0.02 g/100 g). In contrast, the LCCS variety showed superior values for carotenoid, (536.56 ± 58.04-1888.78 ± 35.52) µg/100 g, total sugar (5.77 ± 0.74-46.98 ± 0.39) g/100 g, and protein content, (1.20 ± 0.23-6.68 ± 1.83) g/100 g. The digestate-compost mixture (T4) consistently produced flour with the highest nutritional quality across most parameters. These findings provide valuable insights for optimizing fertilizer strategies to enhance the nutritional and functional value of white-fleshed sweet potato flour.