Effects of drying techniques on cowpea albumin as an egg replacement for meringue cookie applications

In this study, we evaluated the effects of freeze-drying, spray-drying, and vacuum-drying on upcycled cowpea albumin powder and its functional performance in meringue cookie applications. Freeze-drying most effectively preserved protein structure and functionality, resulting in cookies with well-defined air cells, superior texture, and minimal color change. Conversely, spray-drying led to extensive protein denaturation and aggregation due to rapid thermal exposure, which compromised air incorporation and foam stability. Vacuum-drying exhibited intermediate performance, partially preserving protein integrity and exhibiting moderate foaming capacity. Structural and functional analyses revealed that freeze-dried albumin exhibited the highest foaming capacity (133.67 %) and foam stability (53.37 %), along with a significantly lower zeta potential (-6.79 mV) and higher surface hydrophobicity (H₀ = 363.38) compared with the other treatments. These findings highlight the significant role of the drying method in preserving the physicochemical properties of plant-based proteins.