A New Approach with Agri-Food By-Products: A Case Study of Fortified Fresh Pasta with Red Onion Peels

The current study aimed to fortify fresh pasta with red onion peels in the form of powder (OPP). For this aim, three concentrations were used (3%, 6%, and 9% w/w) and properly added to the dough. A control sample was also prepared for comparison (CTRL). Raw and cooked pasta samples were assessed for sensory acceptability and technological properties. Fibre content, total polyphenols, and antioxidant activity (by ABTS and FRAP) were assessed in raw materials and pasta samples. The glycaemic index was also predicted. Results from sensory evaluation and technological analyses demonstrated that with increasing OPP, some defects were perceived to provoke a complete unacceptance with the highest fortification level (9% score < 5). However, these effects were counterbalanced by a significant functional quality increase in fibre content, total polyphenols, and antioxidant activity, justified by the presence of the new onion-based ingredient. Therefore, to better balance benefits and drawbacks of onion peel recycling, a global quality index (GQI) was calculated, which accounted for nutritional improvements and sensory worsening. The most interesting GQI values were found for both 3% and 6% levels of fortification (52.58 vs. 51.86). Considering that these values are very comparable, the 6% can be considered the optimal concentration because it represents the highest concentration to give a fortified and sensorially friendly product.