Comparison of the kinetics of monomeric anthocyanins loss and colour changes in thermally treated blackcurrant, maqui berry and blueberry pulps from Argentina

Abstract: Background: Fruits like blackcurrant, blueberry and maqui berry stand out for their high content of anthocyanins that give products an attractive red colour, in addition to their rich composition of other polyphenols and vitamins. Comprehensive understanding of thermal properties of foods and quantitative changes in quality attributes are necessary for the proper design of thermal processes. Objective: The aim of the present study was to evaluate the kinetics of monomeric anthocyanin (MAcy) and colour degradation due to thermal processing of pulps of blackcurrant, blueberry and maqui berry produced in El Bols´on, Argentina. 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: Activation energies for anthocyanins losses were between 81 and 94 kJ/mol, and for the deterioration of colour between 85 and 89 kJ/mol. In the case of deterioration of anthocyanins, maqui berry presented the highest values of half-life times especially at 90◦C. In the case of colour, blackcurrant showed greater stability showing average colour degradation half-life times between 5 and 11 times higher than those of anthocyanins loss. Conclusions: Kinetic parameters calculated for different berry juices can be used to design a thermal treatment to obtain a high retention of colour and bioactive compounds