Optimization of Spray Drying Conditions for Production of Functional Goat Milk Powder Enriched with Pomegranate Peel Extract (Punica granatum L.)

Background: Pomegranate peel, a by-product of juice processing, is rich in bioactive compounds. Encapsulating its extract offers potential applications in food processing. Milk serves as an excellent carrier for such bioactive compounds due to its widespread consumption. Unlike cow milk, goat milk is more nutritious and provides additional health benefits. However, milk proteins lack phenolic compounds, making supplementation with pomegranate peel extract beneficial. Spray drying is a widely used, cost-effective encapsulation technique for functional food production. Methods: This study aimed to optimize the addition of maltodextrin and the inlet temperature in the spray drying process to produce functional goat milk powder. A Response Surface Methodology (RSM) with a Central Composite Design (CCD) was employed. The independent variables included maltodextrin concentrations (5%, 10%, 15%) and inlet temperatures (160^οC, 180^οC, 200^οC). The response variables were total phenolic content, antioxidant activity, solubility, hygroscopicity, bulk density and whiteness. The optimized functional goat milk powder was further characterized. Result: The optimal conditions were determined as 12.10% maltodextrin concentration and an inlet temperature of 178.98^οC. The resulting functional goat milk powder exhibited total phenolic content of 272.11 mg GAE/g, antioxidant activity of 55.36%, solubility of 95.55%, hygroscopicity of 1.91%, bulk density of 0.46 g/mL and whiteness of 76.89. Characteristics of optimized functional goat milk powder revealed water content of 3.85%, fat content of 26.76% and protein content of 31.23%. FTIR analysis identified the presence of a C=C functional group at absorption bands 1680.73 cm^-1 and 480.38 cm^-1. SEM analysis showed agglomerated small particles, while Particle Size Analysis (PSA) indicated a monomodal distribution with an average particle size of 6.2293 μm.