Gluten free pasta rheology: influence of cooking time on structural features

Abstract

Pasta is a stable food product that is produced mainly by mixing durum wheat semolina and water. It can be consumed after cooking as fresh pasta or can also be dried for future use. Pasta products are one of the most typical Western cereals products and play an important role in nutrition for the worlds population. Improvement in celiac disease diagnosis has led to a rising demand for these convenience products prepared from gluten-free cereals like maize, millet, sorghum, among others. The absence of gluten often results in a liquid batter rather than a dough and results in a big challenge for food research and development, because the network forming ability of gluten needs to be substituted by other means, in order to achieve products with satisfying quality. Pasta cooking is such an important step in pasta processing; pasta of high quality may result in poor quality cooked pasta by the wrong cooking process. Rheology is of considerable importance in the manufacture of pasta dough, it influences the machinability, processing conditions and quality of the final product. This chapter deals with the influence of different cooking conditions on the rheological changes on gluten free pasta. Gluten free pasta dough was prepared; main components were a mixture of corn starch and corn flour, NaCl, a mixture of dry egg powder and ovoalbumin, a mixture of xanthan and locust bean gums and sunflower oil. A factorial design was used to analyze the effect of composition and cooking time on textural and rheological behavior of cooked pasta. Small amplitude oscillatory data (storage modulus, G, and loss modulus, G) was used to obtain the relaxation spectrum and to correlate these results with those obtained at large deformation experiments. The curves were qualitatively similar for all the formulations assayed. G was always greater than G in the frequency range measured and the increase of both moduli with frequency was small. Oscillatory spectra were satisfactorily modeled using the Maxwell Generalized model. Cooking time had a stronger effect on the mechanical spectra than protein and water contents. Hydrothermal treatment produced a significant microstructural change within the network entanglements of the gluten-free pasta dough. For all the formulations studied, water uptake by the matrix, partial gelatinization of the starch and the aggregation of denatured egg proteins led to chemical and morphological changes, which could be observed through the rheological behavior.