Determination of ascorbic acid in Kenyan fresh and processed fruits and vegetables by differential pulse anodic stripping voltammetry (DPASV) and high performance liquid chromatography (HPLC)
Nanyili, Moses Noobsline
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L-Ascorbic acid (L-AA) is an antiscorbutic vitamin widely distributed in plants and animals. It is derived from L -Gulonic acid, a sugar acid and synthesized both biologically and chemically from D-gulonic acid. It is mainly used in the prevention and treatment of survey. In this study, ascorbic acid was determined in 12 different types of fresh fruits, 13 different types of vegetables and 17 different types of processed fruits by both differential pulse annodic stripping voltammetry (DPASV) and high performance liquid chromatography (HPLC). The effect of climatic changes, nature of the soil and boiling on the quantity of L-AA in fresh fruits and vegetables from different regions was investigated using HPLC. These quantities were then compared with the quantities in other regions. In this study, the effect of drying vegetables by the sun and by solar energy, storing fruits for a long time, cutting the vegetables with a sharp knife and a blunt knife and the amount of water used in cooking, on the loss of L-AA was also investigated. The effect of loss of L-AA in cooking when the container is closed or open was also investigated. The highest and lowest mean levels of L-AA among the fresh fruits and vegetables were in red guavas and cowpea leaves, and pineapples and carrots, respectively while in processed peas, and Cocacola and Kenylon whole carrot respectively. Results of the project were discussed and recommendations made.