Impact of Egg White on Rice Bread: A Comprehensive Study of Physicochemical Properties of Rice Dough and Bread Matrix Properties

Rice flour (RF)-based bread typically exhibits low specific volume and high hardness due to the absence of gluten. This study employed egg white (EW) as a quality enhancer, utilizing an RF-EW composite system to simulate the bread-making process and elucidate the underlying mechanisms. The gelatinization behavior demonstrated that EW improved the thermal stability of the system and effectively suppressed starch retrogradation. The rheological analyses demonstrated that EW inhibited starch swelling while modulating viscoelastic properties: At 9% (w/w) EW, both storage modulus (G') and loss modulus (G") reached their minima, whereas creep parameters J_m (retarded compliance) and J_max (maximum creep compliance) peaked, indicating that the system's fluidity had increased, while its texture had weakened. EW, as an inert filler, weakened the system's structure. The interaction forces revealed that hydrogen bonding represented the primary physical interaction between starch and EW. EW proteins were distributed within the interstitial spaces between starch granules, thereby enhancing dough continuity and subsequently improving its gas retention capacity. The final product demonstrated superior quality, characterized by enhanced specific volume, reduced hardness, and a uniform crumb structure. Overall, this study presented a novel strategy for improving rice bread quality and contributed meaningfully to the development of gluten-free bakery products.