Modelling Kinetics of Thermal Colour Degradation in Production of Beetroot Juice Concentrate by Various Heating Methods
Subject Areas : Microbiology
A. Ghorbani Hasan Saraei
1
(استادیار گروه علوم و صنایع غذایی، واحد آیت ا… آملی، دانشگاه آزاد اسلامی، آمل، ایران)
S. A. Shahidi
2
(استادیار گروه علوم و صنایع غذایی، واحد آیت ا… آملی، دانشگاه آزاد اسلامی، آمل، ایران)
M. Mohebbi
3
(استاد گروه علوم و صنایع غذایی، دانشکده کشاورزی، دانشگاه فردوسی، مشهد، ایران)
R. Moaziyan
4
(دانش‌آموخته کارشناسی ارشد، گروه علوم و صنایع غذایی، واحد آیت ا… آملی، دانشگاه آزاد اسلامی، آمل، ایران)
Keywords: Beetroot Juice, concentration, Colour, Kinetics,
Abstract :
Introduction: Preservation of natural colour, as a quality attribute and characteristic ofbeetroot concentrate might be considered as a possibility if the knowledge of kinetic of colorchange is studied thoroughly.Materials and Methods: Three different heating/evaporation processes were employed forthe production of beetroot juice concentrate. The juice was concentrated to a final 40 °Brixfrom an initial °Brix of 10 by microwave heating, rotary vacuum evaporator and evaporatingat atmospheric pressure.Results: The concentration of the final juice at 40 °Brix was achieved in 40, 43 and 70minutes by using microwave, rotary vacuum and atmospheric heating processes, respectively.The changes in colour during the concentration processes were investigated. Total colourdifferences (KE) and L, a and b parameters were used to estimate the extent of colour changesby using Hunter Lab equipment. All colour parameters were decreased with time. The zeroorder,first-order and a combined kinetics model were applied to the changes in colourparameters.Conclusion: The results indicated that the variation in TCD followed both first-order andcombined kinetics models, and parameters L, a and b followed only the combined model.This model implied that the colour formation and pigment destruction occurred duringconcentration processes of beetroot juice.
