Thermal characteristics of dried sugar beet pulp, leaves and leaf fractions obtained after extraction: fibrous leaf pulp and fibre rich leaf fraction, were investigated by differential scanning calorimetry and thermogravimetry. The sugar beet samples showed a similar thermal behaviour associated with a similar composition. Two endotherms are found on the differential scanning calorimetry curves. First one in the temperature range 31-153 °C and the second from 150-160 °C. Thermal degradation kinetics was studied by thermogravimetric analysis. Four degradation stages were observed within the temperature range 25-700 °C. The kinetic parameters of the degradation, obtained by Ortega and Friedman non-isothermal isoconversional methods did not significantly differ between models: Ea-activation energy at a conversion degree 0.1-0.9 ranged 50-200 kJ/mol; lnA- the natural logarithm of the pre-exponential factor 8-48; kp1-thermal degradation rate constant at a conversion extent of 0.5 ranged of 0.19-2.55 min-1. Constant rate of degradation is highest for the sugar beet leaves kp1 (2.58-2.55 min-1), and kp2 (70.1-70.4 min-1). The results obtained are valuable for sugar beet leaf industrial processing. A positive environmental impact is achieved by transforming the waste into high-value food additives.
Keywords: DSC; TGA; activation energy; by-products; enthalpy of transition; kinetics; sugar beet leaves; thermal analysis; thermal degradation.