Phytochemical and anti-nutrient composite from selected marginalized Zimbabwean edible insects and vegetables

Abstract

The aim of this study was to do qualitative screening and quantification of phytochemical and anti-nutrient characteristics of four (4) selected marginalized vegetables (Dicerocaryum zanguebarium, Asclepias densiflora, Hibiscus articulatus, and Corchorus olitorus) and two (2) edible insects (Macrotermes facilger and Henicus whellani) of Zimbabwe. Preliminary qualitative screening showed that the plants and insects primarily contained steroids, triterpenoids, tannins, flavonoids, alkaloids and reducing sugars. On quantification of the phytochemicals and anti-nutrients in both insects and the vegetables, the compounds had the following ranges in 100 g: flavonoids (0.006–15.5 g CE), tannins (0.01–0.5 g CE), total phenolic compounds (0.9–9.37 g GAE), alkaloids (1.19–52.3 g), saponins (4.30–57.0 g DE), oxalates (6.0 g), phytates (0–0.02 g) and cyanogenic glycosides (53.0–119.0 μg HCN). The levels of flavonoids obtained are known to have antioxidant and antimicrobial properties, which produce some physiological action in the human body. However, some of the compounds here studied, like cyanogenic glycosides, tannins and oxalates in the vegetables and insects, might contribute towards anti-nutritional properties due to their presence in high quantities. Aqueous processing methods like boiling and cooking are recommended before consumption of the vegetables and insects, to reduce anti-nutrient concentrations to safe levels. Alternatively, the consumption of marginalized vegetables and insects may be done in moderation.