Optimizing extrusion parameters to develop strawberry by-products-enriched puffed snacks: impact on phenolic composition, textural and physical properties

Strawberry by-products (SBP), generated during industrial processing, are rich in phenolic compounds and dietary fiber. However, they remain underutilized. This study evaluated the feasibility of using SBP as functional ingredients in tapioca starch-based extrudates and optimized extrusion-cooking conditions to improve organoleptic and nutritional quality. A central composite design and response surface methodology were applied to assess the effects of die temperature (DT), feed moisture (FM), and SBP content on expansion index (EI), bulk density (BD), textural properties, color, specific mechanical energy, and phenolic compound contents (PCC). The goal was to maximize PCC and EI while minimizing BD and crispness-related hardness to obtain nutritionally enhanced and texturally appealing snacks. Optimal conditions (DT: 192.01 °C, FM: 18.64 %, SBPC: 16.46 %) maximized PCC, including free (0.67 mg GAE/g Dry Matter) and bound (3.52 mg GAE/g DM) fractions while increased EI (2.15) and reduced BD (0.25 g/cm 3 ) and fracture work (0.7 N mm). High SBP inclusion increased PCC, especially proanthocyanidins, while high FM promoted degradation through reduction of their mean degree of polymerization. These structural changes provide valuable insight into how extrusion conditions could influence proanthocyanidin characteristics. By optimizing extrusion conditions, the present work supports the sustainable valorization of fruit by-products into functional and nutritionally enhanced snacks. • Strawberry by-products increased phenolic compound content in extruded snacks. • Optimal extrusion conditions balanced phenolic content and physical properties. • Proanthocyanidin structure was affected by feed moisture and inclusion level. • Extrusion valorized by-products into snacks with enhanced functional properties.