Comparative Effects of Drying on the Drying Characteristics, Product Quality and Proximate Composition of Some Selected Vegetables (Published)
This study investigated the effects of drying on the drying characteristics, product quality and proximate composition of some selected vegetables. The vegetable investigated were Ocimum gratissimum (Scent leaf), Vernonia amygdalina (Bitter leaf), Moringa oleifera and Heinsia crinite (Atama leaf). These vegetables were collected fresh, sorted, oven dried at 50oC for 12 h and evaluated for drying kinetics, rehydration properties, proximate composition, and total chlorophyll content. The result of drying kinetics indicated that the rate of moisture loss was at its highest in the first and second hour of drying; however the moisture loss was slowed down in the subsequent drying period. The removal of moisture at the end of drying was found to be at a faster rate in the following order: bitter leaf>scent leaf>Moring oleifera leaf>atama leaf. Results of the rehydration properties showed that significantly (p<0.05) higher rehydration ratio and rehydration capacity was obtained in atama leaves (10.56 and 0.223, respectively) while Moringa oleifera recorded the lowest (10.56 and 0.097, respectively). The results revealed that the drying significantly (p<0.05) affected the proximate composition of the dried vegetables with bitter leaf having the highest ash and protein content (11.31% and 29.28%, respectively), atama had the highest fat and carbohydrate content (17.36% and 50.33%, respectively) while Moringa oleifera was highest in crude fibre (19.98%). Total chlorophyll content was higher in the dried vegetables (1.75-3.22mg/100g) than in the fresh vegetable (0.80-1.39mg/100g). In its fresh and dried forms, bitter leaf had the highest chlorophyll content (1.39 and 3.22mg/100g) while chlorophyll retention was highest in scent leaf (67.21%) after drying. This study therefore indicates that drying affects the nutritional composition and product quality of the vegetables differently and that these vegetables in its dried forms are recommended as they supply adequate nutrients.
Anti-Bacterial Effect of Cold Water Extract of Bitter Leaf (Vernonia Amygdalina) on Some Selected Micro Organisms (Published)
Anti-bacterial activities of the leaf of V.amygdalina (bitter leaf) was tested on some microorganisms. Five concentrations 0.5g/ml, 1.0g/ml, 1.5g/m, 2.0g/ml and 2.5g/ml were used and the control experiment was carried out to compare the diameter zones or clearing from the extracts and already standardized antibiotics. Agar well plug method was used for the tests. The bitter leaf extract was made with cold water. Nutrient agar were prepared and inoculated with the different bacteria strains after which wells were made in the in the media and bitter leaf extracts were poured on them. The cold water extracts of V.amygdalina showed inhibitions on the five organisms according to concentration. The organism susceptibility varied with more inhibition to E.Coli, P.aeruginosa, Salmonella typhi, Klebsiella pneumoniae and least to Styaphalococcus aureus.
Mineral and Antinutrients of Fresh and Squeezed-Washed Bitter Leaf (Vernonia Amygdalina) As Affected By Traditional De-Bittering Methods (Published)
The effect of traditional de-bittering methods on the mineral and anti-nutrient components of fresh and squeezed-washed bitter leaf was studied. Palm oil, Potash, Salt and boiling process was used in the squeeze-washing at 3 pre-processing methods of squeeze-wash and periods of 3 to 8 minutes. The percentage retention and losses of mineral and anti-nutrients increased simultaneously during squeeze-washing. Copper, magnesium, calcium and anti-nutrient had retention of 55 to 100% for samples squeezed-washed with palm oil than the other squeeze- washed samples. This could be due to rigidity of the cells which did not allow much nutrients to leach into the squeezed leaf-water. Loss of minerals and anti-nutrients was observed to be influenced directly by the cause-and-effect of disintegration changes which usually leads to softening due to the severity of the squeeze-washing on the bitter leaf instead of cellular composition or level of minerals and anti-nutrients initially present. Palm oil should be used in the squeeze-washing of bitter leaf for better nutrient retention.