Sustainable Recovery of Antioxidant Compounds from Rossa Di Tropea Onion Waste and Application as Ingredient for White Bread Production

From a sustainability and circular economy point of view, this study evaluated the possibility of recovering antioxidant compounds from Rossa di Tropea onion waste for application in the food industry as natural ingredients. In particular, the aim was to investigate the effect of adding natural antioxidants recovered from ‘Rossa di Tropea’ onion waste to maintain/improve the functional and qualitative characteristics of white bread. Total phenolic content, antioxidant activity, and sensorial aspects were studied on the different enriched samples during the storage period. The ‘Rossa di Tropea’ onion skins proved to be a good source of natural polyphenols, and their use in white bread production has resulted in a significant increase in bioactive compound content and antioxidant activity (ABTS and DPPH assays). Moreover, the enriched bread showed acceptable quality attributes in terms of odor, colour, and taste, despite the increase in firmness during the storage time compared to the control sample. The obtained results suggest the possibility of applying the antioxidants recovered by ‘Rossa di Tropea’ onion waste as ingredients in the formulation of bakery products to obtain new food with functional characteristics.