Foaming, physicochemical, and sensory characteristics of foam-mat freeze-dried yogurt powder as affected by egg albumin and maltodextrin contents

Drying technologies for yogurt powder include spray drying, microwave vacuum drying, convective drying, and foam-mat drying. This study investigated the effects of egg albumin (EA) and maltodextrin (MD) concentrations on the foaming, physicochemical, and sensory properties of yogurt powder produced by foam-mat freeze-drying. A D-optimal mixture design was employed with two independent variables: EA (X₁) at 10–20% (w/w) and MD (X₂) at 0–10% (w/w). The responses included foam density, foam expansion, powder recovery, moisture content, bulk density, tapped density, Carr Index (CI), and Hausner Ratio (HR). The optimal formulation was achieved at 16.5% EA and 3.5% MD, yielding a foam density of 0.65 g/cm³ and foam expansion of 52.7%. The resulting yogurt powder exhibited a recovery of 20.1%, moisture content of 3.5%, bulk and tapped densities of 0.35 and 0.38 g/cm³, respectively, with CI = 6.98 and HR = 1.08, indicating excellent flowability and cohesiveness. Sensory evaluation showed that rehydrated yogurt with 75% water addition received the highest acceptability score (mean hedonic value = 6.0, “slightly like”) for color, aroma, flavor, and texture. These findings demonstrate that the optimized foam-mat freeze-drying process effectively produces yogurt powder with desirable physical characteristics, good flow properties, and high consumer acceptability, highlighting its potential for small- and medium-scale yogurt powder production.