For an efficient production of spray‐dried fine powders having controllable properties (size, size distribution, and morphology), finding suitable operating conditions and an appropriate initial composition of the fluid material is important. For this purpose, a suspension device is employed to investigate the drying kinetics of a single droplet of hydroxypropylated pea starch (HPS). In the current work, the effect of the drying air temperature (80–160°C) and of the initial solid content of the agent (15–30%w/w) on the drying kinetics, shrinkage, and locking point of a single droplet was systematically investigated to acquire the optimal conditions required for producing HPS powder using a pilot‐scale spray dryer. In addition to the previously mentioned parameters, the atomization pressure effect (2–3 bars) on the spray‐drying process yield, thermal efficiency, and final powder properties were also considered. A laboratory‐scale X‐ray microtomograph and a camsizer‐XT were employed for the acquisition of three‐dimensional images and surface morphology of single dried particles and spray‐dried powder, respectively. Hollow particles were obtained in all single droplet experiments. The drying kinetic study results were supported by those obtained by the spray drying of HPS. An increased temperature of the drying air and the initial solid content of the solution results in higher powder recovery, lower residual moisture content, and larger particle size. Otherwise, the final particles are larger at a decreased atomization pressure. The optimized parameters for the high spray‐drying process yield (24.54%; 3 bars, 140°C, 25 wt%) and better powder homogeneity (span = 2.31; 3 bars, 140°C, 20 wt%) were defined. A mixture of particle morphologies was observed among the different final powders. A broken shell corresponding to rigid particles was obtained at a drying temperature of 140°C and an initial solid content of 25 wt%. A nonbroken particle refers to a pliable particle that corresponds to inflated and collapsed particles dried at high and low drying temperatures.

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Abstract. Heat capacity prediction and estimation methods of solid organic compounds in terms of temperature are limited, particularly concerning complex molecules with functional groups such as active principles and intermediaries used in pharmaceutical field. Recently a correlation between heat capacity at constant pressure (Cp), temperature and a new concept named mass connectivity index (MCI), for ionic liquids, was published [1][2][3]. In this predictive method, heat capacity can be calculated at different temperatures, if standard heat capacity at 298.15 K is known. The effect of molecular structure on heat capacity is accounted for in this model by the mass connectivity index, a molecular descriptor, which differentiates between compounds. The Valderrama generalized correlation admits, in addition, two universal coefficients, which are obtained from experimental data regression. In the present work, a similar approach is used to predict solid state heat capacity of organics and pharmaceutical products. In order to find model parameters, a database was grouped comprising (104) different compounds and a set of more than 5,791 experimental values of solid state Cps obtained from literature. These collected data were used in multiple linear regression to find model parameters. It was found that the values of predicted heat capacities of compounds non-included in the database were good; they are quite close to the ones presented in the literature. Moreover, this method is simple to use, since only molecular structure of the component and its solid state heat capacity at 298.15 K should be known.