Dynamic study of ascorbic acid degradation in fresh juices of orange, lemon and tangerine as a function of temperature: experimental data and kinetic modelling
Ascorbic acid (AA) is a vitamin present in most natural fruit juices and it has been extensively used in the food industry. The application of AA in food formulations contributes to nutritional value and aggregates quality to the product. Unit operations of the food industry such as drying and evaporation require heating. Ascorbic acid is sensitive to temperature and for this reason, its degradation in plant operations takes place during application of heat. Such degradation affects the sensory characteristics of processed food, such as flavour and colour. Consequently, it is important to know the influence of heating on the thermal degradation of AA. This work presents the dynamic degradation of AA during a heating period of 30 min for three fresh fruit juices. The juices of orange, lemon and tangerine were heated from 15 to 57°C, 15 to 60°C and 14 to 56°C, respectively. These temperature ranges were applied for the reason that the peak of the degradation curve is usually observed at about 60°C. During the heating procedure, samples were taken and the concentration of AA as a function of temperature and time were analysed by titration. A degradation of AA of 14.8% for orange juice, 15.8% for lemon juice and 15.1% for tangerine juice was observed. Kinetic modelling results in valuable information which contributes for the design, operation and optimization of processes. Most of the modelling applied to the degradation of chemical compounds in food formulations is focused on a steady state. This work uses a model based on a transient state and it was solved by numerical integration. Results may be used as a useful tool for operations design and provide clues of the mechanism during AA degradation.
Sarturi, G.N., Robazza, W.S. and Galvão, A.C. (2018). Dynamic study of ascorbic acid degradation in fresh juices of orange, lemon and tangerine as a function of temperature: experimental data and kinetic modelling. Acta Hortic. 1198, 159-162
ascorbic acid, dynamic heating, juices, modelling, thermal degradation