Comparative kinetic modeling of ascorbic acid degradation in commonly consumed vegetables stored in fridge temperatures using computer simulation technique

Abstract

Vitamin C [ascorbic acid (AA)] is one of the most important and popular vitamins, and is 
contained in most fruits and vegetables; the problem with vitamin C is its easy degrada
tion during pre-treatment and storage. In this study, kinetics modeling of degradation of 
AA (vitamin C) in lettuce, cabbage, and carrot common vegetables under fridge tempera
ture ranges of 6.5°C–9.5°C was investigated and samples after storing at various fridge 
temperatures and timing were prepared for analysis and high-pressure liquid chromatog
raphy (HPLC) was used for the determination of the AA of the common vegetable samples 
which consisted of an isocratic elution procedure with ultraviolet-Visible detection at 245 
nm. The rate constants and half-lives were calculated using the integrated law method. 
Activation energy and forecast were determined using the Arrhenius equation and time 
series analysis. Degradation of AA in the commonly consumed vegetables under the same 
pretreatment procedure followed the first-order kinetic model, as the average coefficient 
of determination (R2-value) was greater than 0.91. The rate constant of AA degradation 
for lettuce, cabbage, and carrot under the same fridge temperature condition of 6.5°C 
was 0.5165, 0.3214, 0.2273 day−1, respectively. Their half-lives were 1.3420, 2.1566, and 
3.0494 day−1, activation energies; 19.4052, 23.3180, and 25.7018 Kcal/mol, respectively. 
The ln(C) forecast at 20 days stored at 6.5°C, for lettuce, cabbage, and carrot exhibited 
−3.3537, 0.5080, and 1.8486 mg/100g, respectively. The proposed models at 6.5°C were 
ln(C) = ln( C0
) − 0.5165, ln(C) = ln( C0
) − 0.3214, and ln(C) = ln( C0
) − 0.2273. The most appro
priate vegetable under the same fridge temperature and storage is the carrot because its 
rate constant depicted from the model equations was lower, half-life longer, activation 
energy higher, and forecast longer.