Kinetics of degradation of ascorbic acid by cyclic voltammetry method

Abstract

Cyclic voltammetry was used to examine the kinetics of degradation of ascorbic acid (AA) at different temperatures. It has been shown that the reduction of the concentration of AA in all temperatures follow the kinetics of the first order reaction. The rate constant of the oxidation reaction increases with temperature as follows: 5x10-5; 2x10-4; 1x10-3 and 3x10-3 min-1 at temperatures of 25?C, 35?C, 65?C and 90?C, respectively. The temperature dependence of the rate constant follows Arrhenius equation, and the value of activation energy of the reaction degradation is 48.2 kJ mol-1 . The effect of storage time at a temperature of 90 ?C on AA content in fresh juice of green peppers was investigated. It was shown that AA oxidation reaction in the juice is also the first order reaction, while the lower rate constant in relation to the pure AA (5x10-3 min-1) indicates the influence of other substances present in peppers.

Effects of reaction parameters on self-degradation of L-ascorbic acid and self-degradation kinetics

“…ASA degradation behavior and the effects of temperature and time on the concentration loss of ASA during fruit storage have been investigated (12)(13)(14)(15)(16). Degradation of pure ASA has also been investigated (17,18). An explanation for the degradation behavior of ASA remains unknown.…”

Degradation Kinetic Modelling of Ascorbic Acid from Orange Juice

“…Samples of blood orange juices reveal smaller values for rate constants and respectively half-life times than the orange juices, samples 1 and 2. The rate degradation of ascorbic acid from green pepper increased with the increase of temperature and the values ranged between: 1 × 10 −3 to 5 × 10 −5 min −1 [16]. According to Polydera et al [17] a notable difference in acid ascorbic degradation rates was observed when different types of packaging were used for storage of orange juice.…”

“…Oxygen is the most destructive ingredient in juice causing degradation of vitamin C. The sugar presence could decrease the concentration of dissolved oxygen in juice, thus the oxidation process of ascorbic acid was delayed. Grudić et al [16] found that at room temperature, the ascorbic acid degradation occurs much more slowly: after 6 days the reduction of the concentration is 32% and after 12 days, the percentage is 56%.…”

Barriers and Chemistry in a Bottle: Mechanisms in Today’s Oxygen Barriers for Tomorrow’s Materials

“…Instead of reverting back to L-AA, DHA can also undergo a hydrolysis reaction, forming 2,3-diketogulonic acid through ring cleavage. The resulting acid exhibits further degradation towards the brown-colored 2-furoic acid and 3-hydroxy-2-pyrone [144,145]. Under anaerobic and acid conditions, L-AA may also slowly hydrolyze in a ring-cleavage, degrading to furfural, which also incites a brown coloration [138,139].…”