Effect of Preservation on Two Different Varieties of iVernonia amygdalina/iDel. (Bitter) Leaves

摘要

Vernonia amygdalina Del. is one of the leafy vegetables that can be used in an attempt to alleviate the problem of micronutrient malnutrition, prominent in tropical Africa. In order to ensure availability in non-growing areas or seasons, the vegetable needs to be preserved. Processing and preservation methods influence the nutrient content of vegetables. The present study was aimed at determining the effects of preservation on two different varieties of V. amygdalina (bitter) leaves (broad and small leaves). To this effect, evaluations were made on the chlorophyll content, phytochemicals, and antioxidant capacity of the two varieties of bitter leaf (V. amygdalina Del.) stored at 4℃ and –20℃ over a period of two weeks. Results showed a significant decrease in all parameters studied for both varieties at –20℃ except for the free radical reducing power (FRAP), DPPH radical scavenging activity (%RSA) and nitric oxide radical scavenging activity (%RSA) of V. amygdalina broad leaves where increase in scavenging activity was observed. Thus, it was concluded that to preserve the chlorophyll, phenol, total soluble proteins and reducing sugar levels, preservation at 4℃ is recommended. The present study finding would be useful during short-term preservation of bitter leaves for soup preparation and/or its aqueous extract for ethnomedicinal purposes, especially the small leaf variety.