Microstructural and crystallinity changes in starch-gluten model dough with varying palm oil solid fat content

This study explored the changes in starch-protein-oil interactions during dough mixing and thermal-treated processes using palm oils with different melting points of 38 °C (PO38), 32 °C (PO32), and 24 °C (PO24), and their impact on roasted products quality. The solid fat content (SFC) of PO38, PO32, and PO24 were 29.35 %, 21.53 % and 4.61 % at 25 °C, respectively. Notably, the hardness of fresh dough decreased while its elasticity increased as SFC of fats rise. Higher shear strength was observed in the thermal-treated PO38 dough. Microstructural characterization revealed that PO38 was located at the interface between protein and starch in fresh dough, whereas PO24 appeared as small droplets. Moreover, the fresh PO24 dough exhibited a more continuous gluten network structure. In the thermal-treated PO38 dough, the average length of gluten network was shorter. The thermally treated PO38 dough was more crystalline than the thermal-treated PO32 and PO24 dough, by 27.38 % and 76.76 %, respectively. Furthermore, changes in the hydrophobic interactions of thermal-treated doughs are consistent with changes in protein β-sheet. The findings establish a relationship between the SFC of palm oils and the interaction between dough components during processing, providing important insights for using oils or fats in baked products.