Evaluation of rice pasta properties through new and conventional methods

Quality of gluten-free pasta depends on raw materials composition and, to a greater extent, on the conditions adopted in the pasta making process aimed at forming a tri-dimensional structure of gelatinized and retrograded starch. Samples of rice pasta (spaghetti) prepared following two different processes were considered in this study: sample A, obtained according to the technology adopted in the oriental countries that employs a wet-milled flour as raw material, and sample B, obtained using the conventional process used for wheat pasta production applied to a pre-gelatinized rice flour. Sample characterization included, beside chemical composition, both conventional parameters used for the evaluation of the cooking characteristics of traditional wheat pasta (cooking losses, weight increase, instrumental hardness and adhesiveness) and non-conventional approaches. In particular, bending test was used to evaluate the texture of dry sample, micro-viscoamylographic test to assess the extent of starch modification during pasta production, image analysis for monitoring geometrical changes during cooking, and creep test to evidence viscous-elastic behavior of cooked products. The different technological procedures strongly influenced gelatinization temperature (A=82.0°C; B=67.7°C) and the fracture properties of dry pasta (fracture force: A=1.83N, B=0.55 N; relative deformation at fracture: A=2.38%, B=0.63%). These results pointed out the different macromolecular organization between the two products that reflected upon their cooking characteristics. At their optimum cooking time (9 min for both samples), sample A presented lower cooking losses (3.2g/100g db vs. 5.6g/100g db), higher Young Modulus (0.27N/mm2 vs. 0.36N/mm2), lower adhesiveness (0.67J*10-3 vs. 2.65J*10-3 ) and a more elastic behavior.