Comparative effects of prebiotic addition on the physicochemical and microstructural properties of spray-dried yogurt powder

Abstract

This experimental study examined the effects of inulin and fructooligosaccharides (FOS) additions as partial maltodextrin (MD) replacement on the physicochemical and microstructural properties of spray-dried yogurt powder. Pasteurized whole milk, maltitol, yogurt cultures, and carrier materials were used to make yogurt. The carrier materials were 15% MD (Control), a combination of 5% MD and 10% inulin (Inulin), and a combination of 5% MD and 10% FOS (FOS). Spray-drying conditions were inlet and outlet temperature of 150ºC and 90ºC, with a feed rate of 9 mL/min. Physicochemical properties, solubility, hygroscopicity, particle size, and microstructure of the spray-dried yogurt powder were analyzed. Results showed that replacement of MD with inulin and FOS did not affect product yield (13.16–15.07%), moisture content (2.47–2.70%), and water activity (0.21–0.25) of the powder. Inulin and FOS additions significantly increased powder tapped density compared to the Control (p<0.05), indicating smooth and uniform particle surfaces. Replacement of MD with inulin and FOS improved the solubility of the powder, while addition of inulin decreased powder hygroscopicity and flowability compared to the Control (p<0.05). Mean particle diameters of the powder ranged from 26.43 to 29.99 µm, with morphological structure as spherically shaped with smooth surfaces and varying particle size with uniform distribution. Results suggested that inulin effectively enhanced the quality of spray-dried yogurt powder by reducing hygroscopicity and improving the solubility and tapped density.

Keywords

• spray-dried yogurt powder
• prebiotics
• physicochemical properties
• microstructure