Comparative assessment of oxalic acid levels in fresh, dried and fermented forms of water spinach (Ipomoea aquatica Forsk.)

The current study aimed to comparatively evaluate oxalic acid levels in fresh, dried and fermented forms of water spinach (Ipomoea aquatica Forsk.) (var. Kashi Manu). The field trial was conducted at the Experimental Farm of ICAR-IIVR, Varanasi, India, July, 2024 and estimation of oxalic acid was carried out at the Biochemical Laboratory of same research institute. The oxalic acid content was assessed by titrimetric analysis using standardized potassium permanganate (KMnO₄) solution. The results showed significant differences among treatments (p ≤ 0.01). Fresh samples showed the highest oxalic acid concentration (250.24 ± 3.08 g/100 g) whereas, the lowest value was observed in the fermented sample prepared with salt water (FSW; 22.17 ± 0.68 mg/100 g). Drying reduced oxalic acid levels to 107.66 ± 4.86 mg/100 g whereas, fermentation distinctly reduced the concentration in all treatments with reductions of 83-91 % compared to fresh samples. The decline in oxalic acid concentration during fermentation is attributed to enzymatic degradation and microbial decarboxylation processes. This result revealed that traditional fermentation particularly salt water fermentation, serves as an effective approach for reducing anti-nutritional oxalic acid in water spinach, thereby enhancing its nutritional safety and value for human consumption.