ABSTRACT

The aim of this study was to determine the effect of processing methods on the nutrient, mineral, vitamin and anti-nutrient content of Vernonia amygdalina. The vegetable was harvested from National Root and Crop Research Institute (NRCRI) staff quarters. The vegetable was divided into 5 portions A, B, C, D, and E. Portion A was kept fresh, B was squeeze-washed and boiled, C was squeeze- washed with salt, D was squeeze-washed with oil and E was squeeze-washed and then sundried. The fresh sample of the vegetable served as control. All the samples were analyzed for various nutrients and anti-nutrient on wet and dry weight basis using AOAC methods. Data generated were statistically analyzed. The means were separated and compared. Boiling only increased the moisture content but decreased the content of the other nutrients. The addition of salt while squeeze-washing reduced all the nutrient content except for dry matter, ash, crude fiber, fat, protein, carbohydrate, sodium and flavonoid. There was no significant difference (P>0.05) between the ash content of the fresh and the boiled sample (4.49±0.01% and 4.36±0.00%). For the crude fiber content, the bitter leaf washed with salt, washed with oil and the fresh sample had comparable values (P>0.05) (3.26±0.00%, 3.34±0.85% and 3.24±0.00% respectively). The use of palm oil while squeeze-washing increased the fat, β carotene and vitamin E content of the sample but reduced the content of the other nutrient, vitamin and mineral content. For the fat content, the fresh, boiled and squeezed washed with salt sample had comparable values (2.46%, 2.40% and 2.51% respectively). There was no significance difference (P>0.05) in the zinc content of the fresh and sundried sample (1.67±0.03mg/100g and 1.63±0.00mg/100g) and also no significance difference (P>0.05) in the sundried sample and the sample washed with salt (1.63±0.00mg/100g and 1.61±0.02mg/100g). Sun drying increased the bitter leaf’s dry matter, ash, fiber, fat, protein, carbohydrate content but decreased the content of the other nutrients. There was no significance different (P>0.05) between calcium content of the fresh and the sundried sample (19.61±0.01mg/100g and 19.60±0.00mg/100g). As judged by the result all the processing methods reduced the anti- nutrient content of the vegetable. The addition of salt and palm oil on the overall appears to be the best method that maintained and conserved nutrients, minerals and vitamins composition. Boiling after squeeze washing and sun drying after squeeze washing were of best methods of reducing the anti-nutritional factors of bitter leaf.