Influence of cooking time on the quality attributes and rheology of gluten free pasta

V. LARROSA; G. LORENZO; N. ZARITZKY; A CALIFANO

Viena

Simposio; 3rd International Symposium on Gluten-Free Cereal Products and Beverages; 2013

International Association of Cereal Science and Technology

Pasta products are one of the most typical Western cereals products and play an important role in nutrition for the world?s population. Improvement in celiac disease diagnosis has led to a rising demand for these convenience products with satisfying quality prepared from gluten-free cereals like maize, millet, sorghum, among others. In noodle processing, gluten is mainly responsible for the formation of the structure and its absence results in a big challenge for food research and development. 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. Gluten free (GF) pasta dough was prepared (Lorenzo et al.,2008); main components were a 4:1 mixture  of corn starch and corn flour (53.5%), 1% NaCl, a mixture of xanthan and locust bean gums (2:1,1.5%), 3% sunflower oil, a 10:1 mixture  of dry egg powder and ovoalbumin (EP), and water (W). A 22 design with central point varying added proteins (2.7-6.7%) and water (35.5-37.5%) contents to analyze the effect on rheological behavior of cooked pasta; cooking times ranged between 0-15 min. Small amplitude oscillatory data (storage modulus G? and loss modulus G??) was used to obtain the relaxation spectrum. 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 the two moduli with frequency was small. Oscillatory spectra were satisfactorily modeled using the Maxwell Generalized model. On raw samples the plateau modulus (GN0, a viscoelastic parameter defined for polymers as the extrapolation of the entanglement contribution to the viscoelastic functions at high frequencies) and water content were negatively correlated; EPxW interaction term was also significant. Cooking time had a stronger effect on the mechanical spectra than protein and water contents. Cooking for 5min transformed the raw matrix due to egg proteins gelation, water diffusion, disruption of starch granule structure, and partial starch gelatinization, as was observed by Environmental Scanning Microscopy. A frequency sweep master curve for the cooked system was obtained using GN0 as shift factor. Longer cooking times produced a significant softening of the pasta (smaller GN0); GN0 also slightly diminished when water content increased while raising EP had the opposite effect. Optimal cooking time (the time to disappearance of the core of the spaghetti strand on squeezing) was found to be 10 min. Cooking losses and total organic matter (TOM) in the cooking water, weight gain by the product (WG), Texture Profile Analysis (hardness, adhesiveness, chewiness, cohesiveness, springiness, resilience), firmness (AACC 16-50 pasta blade), and color (CIE-LAB parameters) were determined on GF pasta cooked for 10min to evaluate the effect of water and protein content. Surface Response Methodology enabled definition of mathematical models that accurately described the response of the analyzed variables. Increasing water content produced smaller weight gains, and smaller cooking losses and TOM, while increasing EP levels had the opposite effect, also raising pasta adhesiveness. Cooked GF pasta was more adhesive when EP fraction was larger and average values of firmness and hardness were smaller at higher initial W, positively correlating with higher weight gains.  Cooking strongly affected the color of GF pasta; the cooked product presented smaller luminosity (L*) and yellowness (b*) values than raw dough. EP and W levels, as well as their interaction, had a significant effect on both color parameters (L* and b*) of GF cooked pasta. A multiresponse optimization was used to found the optimum formulation using a desirability function approach.