Effects of shade and sun drying on nutrient composition of hibiscus cannabinus

Abstract

Leafy vegetables are very rich sources of nutrients in diet. However, they are perishable and have short shelf lives after harvest. This study assessed effects of shade and sun drying as methods of preservation or retention of nutrients of Hibiscus cannabinus, a leafy vegetable commonly cultivated in Northern region of Ghana. Freshly harvested leaves of H. cannabinus were either shade or sun dried for 72 hours. Proximate (moisture ash, fat, protein, fibre and carbohydrate) and minerals (calcium, copper, iron, potassium, magnesium, phosphorus and zinc) analysis were done using Association of Analytical Chemists (AOAC) methods. Results showed that sun drying retained more nutrients than shade drying of leaves, which were significant (P < 0.05). Ash, protein, fat, fibre and carbohydrate contents of shade and sun dried leaves were respectively 1.75±0.35 g/100g and 6.91±0.06 g/100g, 2.56±0.03 g/100g and 19.14±0.09 g/100g, 0.78±0.06 g/100g and 4.12±0.04 g/100g, 1.68±0.07 g/100g and 12.19±0.07 g/100g, 7.38±0.12 g/100g and 49.16±0.17 g/100g. Calcium, copper, iron, potassium, magnesium, phosphorus and zinc contents of shade and sun dried leaves were 60.98±0.03 mg/100g and 454.03±0.03mg/100g, 0.03±0.01 mg/100g and 0.28±0.01 mg/100g, 4.36±0.03 mg/100g and 21.58±0.23 mg/100g, 5.60±0.02 mg/100g and 41.33±0.02 mg/100g, 5.33±0.02 mg/100g and 37.87±0.04 mg/100g, 21.31±0.03 mg/100g and 154.16±0.06 mg/100g, 0.26±0.01 mg/100g and 1.81±0.03 mg/100g respectively. Sun dried leaves thus provided more of Recommended Dietary Allowance (RDA) of fibre, carbohydrate, proteins and fat than shade dried leaves. Apart from calcium and phosphorus, sun dried leaves provided more of Recommended Dietary Allowance (RDA) of the mineral than shade dried leaves. Sun drying is therefore recommended for preservation of Hibiscus cannabinus. Continued intake of sun-dried H. cannabinus could significantly increase micronutrient consumption thus reducing micronutrient deficiency among Ghanaian population