Plant materials especially green leafy vegetables contain nutrients and phytochemicals whose consumption has been associated with protecting the human body from chronic diseases. With the aim to promote the utilisation of indigenous leafy vegetables commonly consumed in Botswana, nutrient and phytochemical composition of three leafy vegetables: Amaranth (Amarunthus spp.), Spider plant (Cleome gynandra), and Cowpea leaves (Vigna unguiculata) were evaluated. The moisture content of the vegetables was high ranging from (84.1 ± 0.05 (Amarunthus spp.) to 88.8 ± 0.10% wet basis (Cleome gynandra). The ash content ranged between 1.90 ± 0.06 % (Amarunthus spp.) and 3.0 ± 0.04 % (Cleome gynandra). All the leafy indigenous vegetables were found to be poor sources of protein, fat and fibre. The total phenolics ranged from 10.4 ± 0.5 to 40.4 ± 0.11 mg/g DW. Amarunthus spp. had the highest phenolic content (40.4 ± 0.11mg/g DW). 3,4-dihydroxbenzoic, chlorogenic and ferulic acids were found to be present in Amaranthus spp., 3,4-dihydroxbenzoic, 4-hydroxbenzoic, p-coumaric and ferulic acids where found in Vigna unguiculata whilst vanillic, chlorogenic and ferulic acids were found in Cleome gynandra. Ferulic acid appeared in all the samples analysed, however, chlorogenic acid was the most abundant. The results from the study emphasize the role of these vegetables as a source of nutrients and polyphenols which could contribute to their health promoting properties and offer enormous opportunities for the functional food industry.
Vitamin C is an antioxidant and free radical scavenger for human body. Consumption of Vita C as a nutrient in diet is recommended. Thermal process, environmental factors and pH can cause a negative impact on vitamin content in multivitamin formulation and juices due to physical and chemical instability. Vita C content varies with the age of lemon fruit from unripe to stale. The present paper aims towards content variability and stability studies under various storage conditions like temperature air and pH. Classical methodology like Iodatometric titration is an easy way to trace out the vitamin content in any source using potassium iodate with starch as external indicator. Fresh ripened lemon juice contained 36.5 mg/100ml Vita C, whereas unripened contains 74.6 mg/100ml. Thermal shock of higher degree can decrease the content but for preservation lower temperature was found less deteriorative and deleterious. Percent loss of vitamin were found higher, 56.52 at 80°C and 39.12, 34.8 and 26.3 at 60°C, 40°C and room temperature respectively. Lower temperature shows good retention of vitamin content in the juice so as the percent loss were found 21.9, 13.01 and 8.68 at 12°C , 0°C and -12°C respectively. Air treatments and pH attacks were found harmful for Vita C storage. Storage of it in open bottle in environment the amount was decrease up to with time of min. manipulation of ph using acids and bases also found to decrease the content.