FOOD. Science. Technology. Quality

Food. SCIENCE. Technology. Quality

Food. Science. TECHNOLOGY. Quality

Food. Science. Technology. QUALITY




Temperature characterisation of starch and starch-protein dispersions


The aim of the study was to analyse changes in the parameters describing molecular dynamics of water in starch and starch-protein dispersions taking place in the process of gelation. The study was performed by the nuclear magnetic resonance (NMR) method for starch dispersion samples of the concentration of 0.10g/cm3 (Triticum durum wheat starch) and starch-protein dispersion samples (gluten obtained from wheat) of the concentration c = 0.1g/cm3. NMR measurements were performed in the range of 20°- 70°C. The parameters describing molecular dynamics of water in retrograded gels obtained at 70°C and 100°C were also determined. The process of starch gelation was found to occur already at temperatures lower than 70°C. The spinlattice relaxation times were observed to decrease despite of increase in temperature. It suggested a decreased mobility of water molecules in the system studied. It would result from the formation of spatial lattice formation already in the process of gelation. In the starch-protein samples, the relaxation time, T2, slightly increased with increase in temperature over the whole range studied. In this system water molecules had unlimited mobility, which suggested a lack of gelation. These results were confirmed by analysis of the relaxation times for both systems of retrograded gels obtained at different temperatures. For the starch gel, the relaxation times were identical at both temperatures of gelation. For starch-protein gel the relaxation times are longer for the gel obtained at 70°C than at 100°C. This observation confirmed temperature of 70°C was insufficient for lattice formation.