Effect of Hydrocolloids on starch thermal transitions, as measured by DSC

FERRERO C.; MARTINO M.; ZARITZKY NOEMI

JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY

SPRINGER

Lugar: Berlin; Año: 1996 vol. 47 p. 1247 - 1266

1388-6150

Differential scanning calorimetry (DSC) was used to analyze the influence of different hydrocolloids (xanthan, guar, and locust bean gums, carboxymethylcellulose and sodium alginate) on the gelatinization of corn starch in systems with starch concentration ranging between 0.1 and 0.7 g starch/g mixture. The reduction of available water produced a shift in gelatinization temperature, especially of the conclusion temperature. The effect was more marked for ionic hydrocolloids.The influence of hydrocolloids on glass transition temperature (Tg) of gelatinized starch suspensions and oll the glass transition temperature of the maximally freeze-concentrated solute/unfrozen water matrix (T'g) was also studied. T'g onset values ranged between -4.5 and -5.5 ºC for corn starch pastes with and without hydroeolloids. Those hydrocolloids that increased the viscosity of the unfrozen matrix inhibited additional ice formation during thawing (devitrification).Starch concentration and final heating temperature were found to be relevant factors affecting the kinetics of amylopectin retrogradation during frozen storage at -4ºC. Xanthan gum failed to prevent amylopeetin retrogradation; this observation could be attributed to the fact that gums act outside the starch granule, while amylopectin retrogradation takes place within the granule.