Design and optimization of gluten-free fresh pasta made of red lentil flour heat-treated by turbo-cooking and extrusion-cooking

The increase of gluten-related adverse reactions and the benefits of consuming legumes have led to the development of new food products, such as legume pasta, tailored for an ever-larger segment of the population. In gluten-free pasta, the amount of gelatinized starch and the organization of alternative-to-gluten proteins play a crucial role in providing a well-structured product. Heat treatments can modify techno-functionalities of legume flours, allowing to avoid additives in the final product. The aim of this work was to design and optimise the formulation of legume-based gluten-free gnocchi, a typical Italian fresh pasta. Method: Optimization of gnocchi formulation with red lentil flour (LF) was performed by means of a two-factor I-optimal Design, considering the amount of added water (90-160% with respect to flour weight) and the heat-treatment technologies applied to red lentil flour, turbo-cooking (TC) or extrusion-cooking (EC), as main factors. Dough extrudability was considered as primary response, being related to the machinability in an equipment for artisanal loose gnocchi production. The optimized gnocchi were characterized for main quality parameters and compared with gnocchi produced using a traditional mix (STD) or a gluten-free mix (GF). Results: For the optimization of LF dough, an extrudability range of 5700-7100 mJ was considered as target. The highest desirability value (1.00) was reached with EC-treated flour and 125% added water, obtaining an extrudability value of 7130±771 mJ. The optimized red lentil gnocchi (GN_OPT) were characterized for moisture, texture, weight increase and amount of solid loss in cooking water, which are parameters commonly used to assess pasta quality. GN_OPT had a moisture content (57.6±0.6%) similar to STD (58.1±0.4%) and GF (57.9±0.8%), which could explain the firmness of cooked gnocchi (207±6 N) comparable to that of GF (216±19 N). However, GN_OPT showed a weight increase lower than STD and GF (3.3% vs 6.7-10.9%) and a slightly higher solid loss value (3.2% vs. 1.3-2.6%). Conclusion: These results demonstrated that legume flour can be successfully used in the design of new foods tailored for consumers’ looking for healthy and clean-label products.