Impact of operating conditions on a single droplet and spray drying of hydroxypropylated pea starch: Process performance and final powder properties

Abstract

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.

Unraveling Particle Formation: From Single Droplet Drying to Spray Drying and Electrospraying

“…When applying temperatures above the boiling point of water, the evaporation was accelerated, the formation of a (thinner) crust took place even earlier and at larger droplet diameters, and a larger volume expansion during the inflation/deflation period led to a single big cavity [ 47 ]. The above described general temperature trends and dependencies are in line with studies on a broad selection of solutions: skimmed milk droplets on a glass filament, hydroxypropylated pea starch (HPS) on a polyamide wire, sucrose droplets on a glass filament, poly(lactide-co-glycolide) in ethyl acetate in an acoustic levitator, dextrin droplets in an acoustic levitator, and mannitol droplets on a glass filament [ 49 , 50 , 51 , 52 , 53 , 54 ].…”

“…Single droplet drying experiments are increasingly attracting the attention of the pharmaceutical sector, mostly because they have proven to be of value for the optimization of manufacturing processes such as spray drying and to accelerate process development [ 1 , 50 , 67 , 151 , 152 ]. For example, the morphology of polymer–lactose particles prepared by spray drying was nicely reproduced with the single droplet Drying Kinetics Analyzer™ (DKA) by Nuzzo et al [ 67 ].…”

“…Both et al obtained similar particle morphologies for single droplet drying and pilot-scale spray drying of whey protein and maltodextrin solutions [ 153 ]. Gouaou et al demonstrated that optimal conditions for spray drying of HPS, used for pharmaceutical coating applications, can be determined via SDD experiments [ 50 ]. Additionally, in the food industry, single droplet drying is used to get a better understanding of the spray drying process by identifying critical phenomena during drying.…”

Nanoliposome Powder Containing Shrimp Oil Increases Free Flowing Behavior and Storage Stability

“…Spray‐dried products are spherical since the drying occurs in tiny atomized droplets at very high temperature, thus resulting in rapid moisture migration and constant rate drying at the surface. [ 41 ] However, some spray‐dried powders can have a collapsed structure due to differential shrinkage rate caused by uneven drying at surface and core. [ 42 ] Therefore, the wall materials play a major role in maintaining the spherical shape of powder particles.…”

Fabrication of Concentrated Palm Olein-Based Diacylglycerol Oil–Soybean Oil Blend Oil-In-Water Emulsion: In-Depth Study of the Rheological Properties and Storage Stability

“…Furthermore, these emulsions also exhibited significantly ( p < 0.05) larger particle sizes, with 90% of the overall particle size distribution consisting of mean particle diameters > 10 µm. The span index indicates the width distribution regardless of the median size [ 21 ]. The span index for the emulsion samples after one day of storage ranged between 1.70 and 1.98, whereas critical differences were observed after storage for 30 days, with the dispersion index increasing from 1.50 to 3.50.…”