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

Hacienda Jurica, Querétaro.

Simposio; 11th International Symposium on the Properties of Water; 2010

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. The presence of hydrocolloids and proteins in doughs may modify the availability of water to interact with starch in the gelatinization process. Thermal analysis techniques such as differential scanning calorimetry (DSC) have been widely used to study gelatinization and the amount of unfreezable water in a variety of systems. When a mixture design is employed, the purpose of the experiment is to model the blending surface either to predict the response for any combination of the ingredients or to determine the influence on the response of each component individually and in combination with the other components The aim of the present work was to investigate the effect of proteins and hydrocolloids addition on the water mobility using a triangular mixture design. Basic dough formula consisted in a mixture of corn starch and flour (4:1, 53.5%), 1%NaCl, and 3% sunflower oil, water (35.48-39.5%), gums (xanthan and locust bean gums, 2:1 ratio, 0.512-2.519%), and proteins (dry egg and ovoalbumin mixtures, 10:1ratio, 0.683-6.704%) Combinations of gums, proteins, and water were used in a simplex-centroid design with constrains. Modulated DSC (25ºC to 140ºC, heating rate  5ºC/min, modulated at ±1ºC, period of 60s) allowed to obtain the fusion and gelatinization enthalpies for each sample.  Total amount of water present in doughs was determined by drying them in an oven at 105ºC until constant weight. The experimental data were evaluated using response surface methodology. Usually, the addition of hydrocolloids in frozen dough tends to lower fusion enthalpy, indicating a decrease of freezable water content due to the binding of free water, and helps to control moisture migration. However, in the present work, the response surface analysis of the unfreezable water of this composite system led to a “saddle” type surface, involving several interactions between components. Regarding the process of gelatinization, a biphasic endotherm was observed; when the free water content of the dough was progressively reduced, endotherms shifted to higher temperatures.