A Dissertation Submitted in Partial Fulfilment of the Requirements for the Degree of
Master’s in Life Sciences of the Nelson Mandela African Institution of Science and
Technology
The effects of blanching and drying on micro-nutrients: β-Carotene, Vitamin C, Folic acid,
Iron (Fe), Zinc (Zn), Phosphorus (P) and anti-nutrients: Tannins and Oxalates composition of
False Sesame Leaves (FSL) and Common Bean Leaves (CBL) were investigated. Vegetables
consumption and preservation technologies used were assessed using questionnaire.
Micronutrients content: β-Carotene, Vitamin C, and folic acid were analyzed using HPLC
method while Fe, Zn were determined using Atomic Absorption Spectrophotometer (AAS)
and Phosphorus was determined using UV-VIS Spectrophotometer. The oxalate and tannin
were determined by titration and Folin Ciocalteu method. Several vegetables consumed were
identified, FSL (16.9%) (Bahi) and CBL (21%) (Mbeya rural) were one of those. In vegetable
processing, boiling (76.9%) and sun drying (15%) were reported in Bahi and Mbeya Rural
Districts, respectively. Sun drying was the commonly used method in both Districts. Folic
acid and β- Carotene were below detection limits in both vegetables. The vitamin C content
in fresh FSL and CBL was 16.28 and 5.48 mg/ 100g, respectively, yet the content was
significantly reduced (p<0.05) by blanching and sun drying. False sesame leaves contained P
(700 mg/kg), Fe (115.75 ± 2.23
mg/kg) and Zn (14.13 mg/kg) whereas in CBL P was 600
mg/kg Fe (652.76 mg/kg) and Zn (41.04 ± 0.28 mg/kg). Levels of P, Fe and Zn were
significantly (p<0.05) increased by sun drying. Tannin and oxalate content in blanched and
sun dried leaves were lower than in fresh leaves. Sun drying of FSL and CBL while covering
after blanching further reduced tannins and oxalates, thus it is recommended as an effective
method in anti-nutrients elimination.