Upcycling of tomato by-products in food: quality improvements and life cycle assessment

Abstract

This study investigates the upcycling of tomato peels and seeds (TPSs) as functional ingredients for fortifying pasta and gnocchi within a circular bioeconomy framework. The incorporation of TPSs resulted in marked nutritional enhancements, with total dietary fiber increasing by up to much more than 100% in both pasta and gnocchi, and significant improvements in antioxidant activity (ABTS and FRAP assays) and bioactive compounds such as polyphenols and flavonoids (increases of up to ∼20–60% depending on formulation). Despite minor sensory changes associated with TPS addition, all formulations retained acceptable scores (>5 on a 9-point scale), indicating that acceptability was preserved even at the highest enrichment levels. Notably, the impact on sensory quality was limited and formulation-dependent, with optimized samples successfully balancing technological feasibility and palatability. From an environmental perspective, Life Cycle Assessment (LCA) showed that the energy demand associated with additional processing steps (drying and milling) partially offsets the environmental benefits, particularly in terms of Global Warming Potential (GWP). However, the incorporation of TPSs still supports the valorization of agro-industrial by-products and compensates for the reduced use of conventional raw materials. The integration of sensory, nutritional, and environmental indicators through the Global Quality Index (GQI) demonstrated a clear net positive balance for all TPS-enriched samples. In particular, gnocchi showed the highest overall performance, confirming their suitability as a carrier for TPS incorporation. These findings demonstrate that TPS upcycling represents an effective and sustainable strategy to develop nutritionally enhanced staple foods, supporting waste valorization while retaining satisfactory sensory quality.