Physical characterization of spray-dried milk powders and their agglomerates with the addition of carob, cinnamon, and ginger powders

Abstract

The scope of the study is to determine the influence of the addition of different amounts of carob (CP), cinnamon (CNP), and ginger (GP) powders and fluidized bed agglomeration process on the moisture content, water activity and powder properties of milk powders as well as powder yield and the energy consumption of the drying and agglomeration operations. CP, CNP, and GP were directly added to whole milk at different concentrations (1-8 % by weight), mixed for 30min and filtered by crude filter paper. Then, the filtrate was spray dried at the inlet and outlet air temperatures of 160 and 80 °C respectively. The powder yield ranged between 55.57-67.07% for milk powder with CP (MPCP), 45.48-61.04% for milk powder with CNP (MPCNP), and 42.42-46.93% for milk powder with GP (MPGP). The addition of the powders decreased the total drying time and energy consumption of the drying process (p<0.05). The agglomeration process was performed at 1.8 m/s, and 80 °C for 15 min. During this process, water (1:0.1 weight: weight, water: powder) was added to powders as a binder. Agglomerates have higher moisture content (3.45-4.60%, wet basis) and water activity (0.171-0.257) values compared to corresponding powders. The solubility times of powders decreased with the increasing amount of ingredients. Higher bulk (200-259 kg/m3) and tapped (339-400 kg/m3) density values were obtained from MPGP compared to other powders. Agglomeration process improved the flow properties of milk powders and increased the bulk and tapped density values. The long solubility times of milk powders (194-244.5 s) reduced to 10-50 s by means of the applied agglomeration process.