USE OF DIFFERENTIAL SCANNING CALORIMETRY AND THERMOGRAVIMETRIC ANALYSIS TO CHARACTERIZE THE THERMAL-DEGRADATION OF CRYSTALLINE SUCROSE AND DRIED SUCROSE-SALT RESIDUES
G. Eggleston et al., USE OF DIFFERENTIAL SCANNING CALORIMETRY AND THERMOGRAVIMETRIC ANALYSIS TO CHARACTERIZE THE THERMAL-DEGRADATION OF CRYSTALLINE SUCROSE AND DRIED SUCROSE-SALT RESIDUES, Journal of agricultural and food chemistry, 44(10), 1996, pp. 3319-3325
Thermal degradation of pure sucrose in concentrated aqueous solution (
100 degrees C, similar to 65 degrees Brix) in the presence of KCl, LiC
l, NaI, and Na2B4O7 was investigated. Polarimetry was used to quantify
sucrose degradation, and pseudo-first-order kinetic constants of init
ial degradation rates were calculated. All salts significantly increas
ed sucrose degradation; colored degradation products were only formed
in the presence of Na2B4O7. Thermal degradation characteristics of cry
stalline sucrose and dried, crystalline residues from sucrose-salt mod
el solutions heated at 100 degrees C for 0 and 3 h were further invest
igated by differential scanning calorimetry (DSC), thermogravimetric (
TG), and differential thermogravimetric (DTG) analyses. Rate of heatin
g was 15 degrees C/min from 50 to 500 degrees C. DSC and TG studies co
nfirmed the catalytic nature of salts on the thermal degradation of su
crose. Salts affected thermal degradation in various ways. The initial
condensation degradation reactions were more rapid than expected, and
subsequent elimination reactions were slower. The thermal analysis re
sults indicate that complexation between the salt and sucrose is occur
ring, and further study at the molecular level is required.