Response surface methodology to assay the effect of the addition of proteins and hydrocolloids on the water mobility of gluten free pasta formulations

VIRGINIA LARROSA; GABRIEL LORENZO; NOEMÍ ZARITZKY; ALICIA CALIFANO

Water Stress in Biological, Chemical,Pharmaceutical and Food Systems

Springer

Lugar: New York; Año: 2015; p. 367 - 374

In a gluten free pasta formulation (suitable for celiac people), the influence of each constituent has a major importance on the final product quality, especially water and hydrocolloids contents used to replace the gluten matrix. Gluten-free doughs are mixed dispersed systems; the dispersion medium contains several types of dispersed particles, with two main construction materials: polysaccharides and proteins. The amount of water content and the presence of different components such as sugars, gums and proteins affect the extent to which the amorphous regions are plasticized during gelatinization, modifying the corresponding enthalpy and the peak temperature in a differential scanning calorimetry (DSC) thermogram. The extent of hindered mobility of water molecules is related to the amount of the unfrozen water content of the systems and their glass transition temperature (Tg) and influences the conditions for starch gelatinization. The aim of this chapter is to use the Response Surface Methodology to analyze the effect of proteins and hydrocolloids addition on water-starch interaction during gelatinization in gluten free doughs using a triangular mixture design, through the analysis of thermograms obtained by modulated differential scanning calorimetry (MDSC). The amount of unfrozen water, water melting temperature, and glass transition temperature (Tg). for each formulation are also studied, and their relationship with dough composition is determined. In the present work a simplex-centroid augmented design with constraints was chosen to study the effect of adding gums (0.51-2.52%), protein (0.68-6.70%), and water (35.5-39.5%).  Thermograms were performed from -50ºC to 140ºC, at a heating rate of 5ºC/min, with a modulation of ±1ºC and a 60s period, using a modulated DSC. The latent heat of water melting was obtained by integrating the melting peak of the thermograms; this value was used to estimate the frozen water fraction in the food material. For all the formulations assayed in this work, thermograms show the characteristic water melting peak between -5 and -8ºC and above 65ºC starch gelatinization transition. The response surface analysis of the unfrozen water of the composite systems led to a ?saddle? type surface involving several interactions between components, were the largest influence corresponded to gums and the interaction between gums and water. The dependence of peak melting temperature on water, proteins, and hydrocolloids content also showed a saddle-like effect. Glass transition temperatures were around -26ºC (from -24 to -29ºC) for all the tested formulations. Particularly, it could be observed that increasing the amount of water available to freeze in the dough produced a decrease in Tg. A biphasic endotherm was observed in the gelatinization transition for all formulations and a significant displacement to higher temperatures of the endotherms was observed when the hydrocolloids content was increased or water content decreased.