RETROGRADATION OF AMYLOPECTIN AND THE EFFECTS OF AMYLOSE AND ADDED SURFACTANTS EMULSIFIERS

The retrogradation of mixtures with different amylopectin/amylose ratios and 50% (w/w) water content was followed by differential scanning calorimetry. The effect of the addition of surfactants/emulsifiers (sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide (CTAB) and monoglycerides) was investigated. The results showed that the relationship beween the melting enthalpy of recrystallized amylopectin and the proportion of amylopectin was not linear. Mixtures with less than 50% amylopectin showed a higher melting enthalpy than expected. The effect of surfactants/emulsifiers on that relationship was to decrease the retrogradation of all the mixtures, but they had their greatest effect on 100%-amylopectin samples and least effect on mixtures with 50% amylopectin. Thermograms obtained for 100% amylopectin with added surfactants/emulsifiers showed transitions above 100°C, thus indicating the formation of a complex between amylopectin and the surfactants/emulsifiers. This was supported by X-ray diffraction analysis, as amylopectin samples with added SDS and CTAB showed a mixture of B- and V-patterns. This complex formation between amylopectin and surfactants/emulsifiers can explain the large reducing effect of the addition of surfactants/emulsifiers on retrogradation of 100% amylopectin samples, and partly the retrogradation of other mixtures. © 1990.