Influence of drying and cooking methods on the nutritional value of four native mucilaginous vegetables consumed in Benin

Abstract

Native vegetables are rich in macronutrients and bioactive micronutrients, including antioxidants. Post-harvest treatments and different ways of cooking vegetables affect their nutritional and functional qualities. The impact of drying and cooking methods on the nutritional value and antioxidant properties of Adansonia digitata L., Bombax brevicuspe Sprague, Ceiba pentandra (L.) Gaertn leaves and Grewia venusta Fresen flowers was investigated. The protein, lipid, fibre, mineral and polyphenol contents of vegetables were analysed using reference methods as per AOAC (Association of Official Analytical Chemists). The results show that shade-dried during harmattan increases the protein (27.63%) and lipid (77.66%) contents of A. digitata, the protein (19.25%) and fibre (30.55%) contents of B. brevicuspe, the fibre (24.59%) contents of G. venusta and decreases the lipid (- 2.90%) contents of C. pentandra. Cooking results in higher losses of iron (-16.26% to -71.96%), calcium (-52.09% to -78.13%) and vitamin C (-44.78% to -75.77%). Cooking also affects the antioxidant activity of the four vegetables, resulting in a decrease in polyphenol levels (-74.48%) of A. digitata, (-87.56%) of B. brevicuspe, (- 80.03%) of C. pentandra and (-94.26%) of G. venusta. To ensure that the quality and quantity of nutrients in these vegetables are preserved, it is important to review traditional drying and cooking methods.