Effects of Different Extracting Solvents on Non-Phenolic Phytochemical Profiles of Selected Nigerian Spices and Spice-treated Foods

Abstract

The aim of this research was to investigate the impact of extraction solvents on the non-phenolic phytochemical profiles of selected spices (Ocimum viride, Monodora myristica, Monodora tenuifolia and Tetrapleura tetraptera) and spice-treated foods in southern part of Nigeria. The spice samples were processed into powder for antioxidant screening. The spice extracts were obtained from the samples using 5 extracting solvents [distilled water, 95 % methanol, acetone / hexane (1:1 v/v), n-hexane / methanol / acetone (2:1:1, v/v/v) and acetone / water / acetic acid (70:29.5:0.5, v/v/v)]. Water extracts were obtained from beef, pork and fluted pumpkin leaves. The alkaloid, saponin, oxalate and phytate components of the spice extracts and the spice-treated foods were evaluated using standard methods. The laboratory analyses were performed at analytical laboratory, National Centre for Energy Research and Development, University of Nigeria, Nsukka during the 3rd quarter of 2020. The percentage yield of the extracts were low (0.32 - 0.96 %) and varied widely among extracting solvents, spices and spice-treated foods. M. myristica and T. tetrpleura had the highest yield, 0.96, in methanol extracts. Phytochemical contents differed significantly (p < 0.05) among spices, extracts of the same spice and among spice-treated foods. Spices had high contents of oxalate (2.0 – 7.0 mg/100 g), alkaloid (0.8 – 5.76 mg/100 g) and phytate (2.14 – 3.88 mg/100 g) but relatively low content of saponin (0.03 – 0.736 mg/100g). Methanol alone or in combination with other solvents extracted higher amounts of phytochemicals (0.96 %) than other solvent mixtures from the spices. Phytochemical contents of spice-treated foods were in the order: vegetable > rice > pork > beef.