29D-27 |
Products of sucrose caramelisation kinetics: Fructose, glucose and aromatic and coloring agents |
M. QUINTAS, A. L. Mota, T. R. S. Brandão, R. M. Cruz, and C. L. M. Silva. Escola Superior de Biotecnologia, Universidade Católica Portuguesa, R. Dr. António Bernardino de Almeida, 4200-072 Porto, Portugal Caramelisation occurs when sucrose is heated in a concentrated solution. At traditional reaction conditions, high sucrose concentration, neutral pH and absence of impurities, a lag phase in sucrose degradation can be observed. As the degradation of sucrose proceeds, products of sucrose caramelisation are produced: fructose, glucose and aromatic and color agents (e.g. 5-hydroxymethyl-2-furaldehyde (HMF) and 2-furaldehyde (furfural)). The objective of this work is to study the formation of these products. Samples with different levels of sucrose concentration (from 75 to 97%) were heat treated, at different temperatures (from 100 to 180°C), and the reaction products were quantified using HPLC technique. The results obtained confirm the existence of a lag phase in the reaction of sucrose degradation, which depends on concentration and temperature. As the reaction proceeds, fructose and glucose are produced. Their concentration showed a peak followed by degradation until equilibrium is reached; HMF and furfural are formed latter in the reaction. The maximum reaction rates of all the studied compounds were dependent on temperature, following an Arrhenius type behavior. The results obtained are of utmost importance for industrial use, since they can provide information for the optimization of the caramel production and also for preventing the reaction, when it is undesirable (e.g. in the nut coating or syrup fabrication).
Session 29D, Food Engineering: Thermal processes
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