Phytochemical, Antioxidant and Spectral Characteristics of Moringa Herbal Tea Processed Using Different Methods

The study examined the effect of processing methods on the phytochemical, antioxidant and the spectral characteristics of Moringa herbal tea. Fresh Moringa oleifera leaves were processed into moringa herbal tea using four different methods namely; Oven-dried (OD), Blanched-Oven-dried (BOD), Oxidised-Oven-dried (OOD) and solid-state Fermented Oven-dried (FOD). Phytochemical analysis consists of total phenolic, total flavonoids, saponins and alkaloids. Analysis revealed that total phenolic content was in the range of 2.278±0.041 mg/mL GAE to 1.745±0.081 mg/mL GAE. The total flavonoids were in the range of 2.93±0.001 mg/mL QAE to 2.582±0.008 mg/mL QAE. Alkaloids were estimated as follows: 22.350±0.891 % DW to 8.83±0.72 % DW and saponins, 7313±0.272 % to 2.94±0.088% DW. Antioxidant activities reveals hydrogen peroxide assay in the range of 3.315 ± 0.001% to 5.103 ± 0.004% and total and the ferric reducing/antioxidant power (FRAP) assay was in the range of 4.836± 0.067% to 7.173 ± 0.010% of AAE. Spectral findings revealed that the λ-max of herbal tea samples were in the range of 380-396 nm. Major observed FTIR frequencies were 3280.1 cm-1, 2918.5 cm-1, 2847.7 cm-1, 1606.5 cm-1 and 1025.0 cm-1, corresponding to; amides, alcohol, alkene, aldehydes, aromatic amines, and esters. Infusion time had no effect on the UV-Visible spectral profile of tea samples, while the processing method affected the spectral profiles for both FTIR and UV-Visible spectral profiles. These spectroscopic methods have shown to be fast, efficient and highly sensitive, they require little sample preparation, and are usually environmentally friendly.