Spectrophotometric Determination of Ascorbic Acid Content in Selected Fruit Juices Sold in Lagos State Supermarkets

Ascorbic acid, commonly known as Vitamin C, is an essential micronutrient required for collagen biosynthesis, immune function, and antioxidant defence. Commercially processed fruit juices are frequently marketed as rich sources of ascorbic acid; however, storage conditions, processing methods, and shelf life significantly affect the actual vitamin content. This study evaluated the ascorbic acid content of ten commercially available fruit juice brands sold in supermarkets across Ikeja, Lagos Island, and Victoria Island in Lagos State, South West Nigeria. Samples were purchased at two different time points within the product shelf life and analysed using the 2,6-dichlorophenolindophenol titrimetric method and UV-Visible spectrophotometry at 243 nm. Results were compared against manufacturers' label claims. Significant variation was found between declared and measured ascorbic acid concentrations, with certain brands showing losses exceeding 35% of the labelled value. Refrigerated storage was associated with better retention compared to ambient temperature storage. These findings raise concerns about consumer information accuracy and the reliability of nutritional labelling regulations currently enforced by the National Agency for Food and Drug Administration and Control in Nigeria. The study recommends stricter post-market surveillance of vitamin content claims on commercially distributed beverages in Nigeria. Keywords: ascorbic acid, fruit juice, spectrophotometry, nutritional labelling, Lagos State.