Influence of extrusion on starch structure, physicochemical properties and in vitro digestibility of banana flour (Musa spp.) and its potential application in wheat dough

Despite growing interest in improving the processability of green banana flour (GBF), few studies have examined how extrusion impacts its starch structure, digestibility, and potential applications. This study explored the effects of extrusion conditions, specifically feed moisture (FM) and extrusion temperature (ET), on starch structure, physicochemical properties, and in vitro digestibility of GBF, along with its application in wheat dough formulations. Extruded GBF (EGBF), particularly at low FM, exhibited increased degree of gelatinization and amylose content but reduced relative crystallinity, gelatinization temperature, and enthalpy. Extrusion under optimized FM facilitated leaching of higher molecular weight starch molecules, enhancing water solubility. Additionally, EGBF showed irregular structures, increased water absorption, and improved thermal stability and anti-retrogradation properties. Under low FM and high ET conditions, intensified starch degradation promoted digestibility and elevated slowly digestible starch content. In wheat flour blends, EGBF increased gelatinization temperature, thermal stability, and cold paste stability. EGBF addition inhibited gluten network formation but reinforced dough strength at a 10 g/100 g inclusion through gelation among gelatinized starch molecules. The microstructure demonstrated that EGBF enhanced the structural continuity of wheat dough. The findings offer theoretical support for the development and utilization of green banana-derived starch products in wheat-based dough applications. • Extrusion improves the functional properties of green banana flour (GBF). • Extruded GBF (EGBF) exhibits increased digestibility and slowly digestible starch. • EGBF shows higher water absorption and improved pasting viscosity stability. • Feed moisture has a greater effect on extrusion than extrusion temperature. • EGBF reinforces dough strength and improves wheat dough structure at 10% level.