This study aims to provide an in-depth understanding of the effects of blanching pretreatment on the preservation of antioxidants, phytochemicals, and mineral contents in Corchorus olitorius, for optimal retention and utilization. Three distinct varieties of C. olitorius seeds, namely Ewedu_Abeokuta, Ewedu_Yaya, and Ewedu_Eleti_Eku, were sourced from farmers and cultivated.
The harvested leaves underwent a 2-minute blanching treatment at 60 °C. Subsequent spectrophotometric-based assays were employed to quantify the biochemical contents. At IC100, Ewedu_Eleti_Eku (blanched) exhibited the highest 2,2-diphenyl-1-picryl hydrazyl (DPPH) activity (81.87 ± 0.10), which was statistically similar (p ≤ 0.05) to that of Ewedu_Yaya (blanched) (76.92 ± 3.62).
The Ferric ion Reducing Antioxidant Power (FRAP) revealed Ewedu_Abeokuta (blanched) to have the highest antioxidant activity across tested concentrations (IC25 =17.43 ± 29.83, IC50 =20.53 ± 34.98, IC75 =25.13 ± 42.82, and IC100 =24.93 ± 42.11), when compared to the other varieties. Ewedu_Abeokuta (blanched) showed significantly higher (p ≤ 0.05) Magnesium (Mg) and Selenium (Se) content, with values of 54.60 ± 2.63 and 0.40 ± 0.01, respectively.
In contrast, Ewedu_Yaya (blanched) had the highest Zinc (Zn) content (6.17 ± 0.05 Zn), which was statistically similar (p ≤ 0.05) to Ewedu_Eleti_Eku (blanched) (5.69 ± 0.84). The FRAP assays (IC25, IC50, IC75, and IC100) demonstrated perfect positive correlations (r = 1) among themselves, indicating a consistent linear relationship.
The treatment further enhanced phenol and tannin content in Ewedu_Yaya and phenol content in Ewedu_Eleti_Eku. These findings suggest that blanching pretreatment can be a valuable technique for improving various quality attributes of C. olitorius varieties.