Thermal degradation kinetics of monomeric anthocyanins, colour changes and storage effect in elderberry juices
Abstract
BACKGROUND:
Elderberry (Sambucus nigra L.) is considered an interesting fruit as food ingredient, due to its high content of anthocyanins that give products an attractive red colour.
OBJECTIVE:
The aim of present study was to evaluate the kinetics of elderberry monomeric anthocyanin (MAcy) and colour degradation due to thermal processing and storage.
METHODS:
Anthocyanins content was measured with pH-differential method. CIELab parameters were obtained with a Minolta Spectrophotometer, total phenolics were determined by Folin-Ciocalteu method. MAcy degradation and evolution of colour parameter a* were fitted to a first–order model. RESULTS: The degradation rate of a* was about three times lower than MAcy degradation rate. Activation energy for degradation of a* and MAcy were 140.6 and 144.6 kJ mol−1 respectively. Degradation rates (k) obtained during storage were 0.025 d−1 for MAcy and 0.0064 d−1 for a*. During storage, 50% reduction of initial values was at 120 days for MAcy and at 432 days for colour parameter a* at 25°C. However, a high retention of polyphenols and antioxidant was noted.
CONCLUSIONS:
Kinetic parameters calculated for elderberry juice can be used to design a thermal treatment to obtain a high retention of colour and bioactive compounds.
