Journal of Food Research and Technology | July-September, 2014 | Vol 2 | Issue 3 | Pages 106-112 © 2014 Jakraya Publications (P) Ltd JOURNAL OF FOOD RESEARCH AND TECHNOLOGY Journal homepage: www.jakraya.com/journa/jfrt ORIGINAL ARTICLE An Investigation into the Degradation of Ascorbic Acid in Solutions Claire D. Munialo a,b and Vassilis Kontogiorgos a* a Department of Chemical and Biological Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, UK. b Physics and Physical Chemistry of Foods, Department of Agro-technology and Food Sciences, Wageningen University, P.O. Box 17, 6700 AA, Wageningen, the Netherlands. * Corresponding Author: Claire Munialo Email: Claire.munialo@wur.nl Received: 04/06/2014 Revised: 27/08/2014 Accepted: 27/08/2014 Abstract The kinetics of the degradation of ascorbic acid (AA) in solution during heating at 30, 50, 70 and 90°C for 180 min and during 7 weeks of storage at 4°C and 20°C were investigated. The concentration of AA in solution was determined by the fluorimetric method before heating and storing the samples under different conditions. The retention of AA after heating at 30, 50, 70, and 90°C and storage at 4°C and 20°C was 87.6, 84.7, 73.8 and 43.6% (for heated samples) and 74.3 and 77.7% (for stored samples) respectively. Overall, there was a significant correlation (p<0.05) between the loss of AA as a result of heating of the samples or the storage of the samples at 4°C or 20°C. The degradation of AA in aqueous solution at each temperature was shown to follow a first-order kinetic model. The temperature-dependence of degradation was adequately modelled by the Arrhenius equation. The activation energy was 6.06 kcal/mole (for samples subjected to heat treatment) and 1.30 kcal/mole (for samples stored at 4°C and 20°C). The Q 10 values were found to be 1.3 (for samples subjected to heat treatment) and 1.1 (for samples stored at 4°C and 20°C). The results from this study show that AA is a labile nutrient that can be easily lost during storage or processing. The results from this study contribute to the enhancement of the knowledge of the parameters that are of significance in the degradation of AA and thus provide an understanding of the conditions that can be used to optimize heat processing and storage of liquid foods that are rich in AA such as fruit juices. Keywords: Ascorbic acid, temperature-dependence, stability, degradation, fluorimetric method. Introduction Vitamin C (ascorbic acid) is known to be one of the most unstable nutrients found in food (Moreira et al., 2006). Several studies have demonstrated the rate of ascorbic acid (AA) degradation in various foods (Sinha et al., 2012). Thermal degradation of AA has been reported to be one of the many routes of vitamin C loss from foods (Castro et al., 2004). The substantial loss of AA has also been reported to occur via the mechanism of leaching given that AA is highly soluble in water (McKillop et al., 2002). Several methods such as titration with dichlorophenolindophenol (DCPIP) dye, high performance liquid chromatography, spectrophotometric, fluorimetric and turbidimetry have been used for the analysis of AA (Rodriguez et al., 1992). In all mentioned methods of AA analysis, the fluorimetric method was reported to be the most accurate as it measures both AA and dehydroascorbic acid, which are the active forms of vitamin C (Nakajima et al., 2009). Several authors have reported instability of AA during storage and thermal processing. Studies on process optimization of foods have reported AA to be more sensitive to thermal degradation in natural products than in buffered model systems (Oliveira, 1998). L-ascorbic acid was shown to be more sensitive to heat in oranges than in tomatoes (Van den Broeck et al., 1998), whereas the storage temperature was shown to be the most important factor that determines the stability of AA against degradation (Roig et al., 1995). Low temperature storage was reported to be imperative in order to study L-ascorbic acid decay (Roig et al., 1995). Furthermore, L-ascorbic acid was found to be