Spray-drying pretreatment enabled low-alkaline, highly transparent egg white gels: pH-dependent dual mechanisms in aggregation behavior and gel network formation

To address the quality deterioration associated with the strong alkalinity required for conventional transparent egg white (EW) gels, this study explored spray-drying (SD) pretreatment as a strategy to reduce the required pH, although its mechanism remained unclear. The effects of SD pretreatment on gel transmittance, protein aggregation, and gelation kinetics were systematically investigated under different alkaline conditions. Results showed that gels prepared from SD-pretreated egg white powder (EWP) achieved a transmittance of 57.55% at pH 9.5, comparable to that of untreated EW gels (58.61%) under strongly alkaline conditions (pH 11). Furthermore, the transmittance of EWP gels increased with increasing pH, governed by distinct mechanisms. At moderately alkaline pH (9.5-10), the EW gel transmittance reached 57.55-70.71%. This was mainly because SD pretreatment increased EW aggregate size and slowed gel network formation, thereby promoting a well-ordered gel network. At strongly alkaline pH (10-11), the EW gel transmittance rose to 78.87-87.12%, primarily because SD pretreatment dramatically suppressed the aggregation of alkali-induced EW protein peptides, ultimately forming a gel network with larger pores and high water-holding capacity. These findings demonstrated that SD pretreatment would be a promising strategy for producing high-value transparent EW gels without strong alkalinity. • Spray drying converted egg white gels from opaque to transparent above pH 9.5 • Aggregation degree and network pore structure governed egg white gel transparency • Spray drying enhanced gel transparency by slowing gelation in moderate alkalinity • Spray drying enhanced gel transparency by inhibiting aggregation in strong alkalinity