Effect of Spray Dryer Scale Size on the Properties of Dried Beetroot Juice

Abstract

Experiments detailing the spray drying of fruit and vegetable juices are necessary at the experimental scale in order to determine the optimum drying conditions and to select the most appropriate carriers and solution formulations for drying on the industrial scale. In this study, the spray-drying process of beetroot juice concentrate on a maltodextrin carrier was analyzed at different dryer scales: mini-laboratory (ML), semi-technical (ST), small industrial (SI), and large industrial (LI). Selected physicochemical properties of the beetroot powders that were obtained (size and microstructure of the powder particles, loose and tapped bulk density, powder flowability, moisture, water activity, violet betalain, and polyphenol content) and their drying efficiencies were determined. Spray drying with the same process parameters but at a larger scale makes it possible to obtain beetroot powders with a larger particle size, better flowability, a color that is more shifted towards red and blue, and a higher retention of violet betalain pigments and polyphenols. As the size of the spray dryer increases, the efficiency of the process expressed in powder yield also increases. To obtain a drying efficiency >90% on an industrial scale, process conditions should be selected to obtain an efficiency of a min. of 50% at the laboratory scale or 80% at the semi-technical scale. Designing the industrial process for spray dryers with a centrifugal atomization system is definitely more effective at the semi-technical scale with the same atomization system than it is at laboratory scale with a two-fluid nozzle.

Spray Drying of Chokeberry Juice—Antioxidant Phytochemicals Retention in the Obtained Powders versus Energy Consumption of the Process

“…It directly determines the level of raw material losses during the process, which should be as low as possible. In industrial practice, it is expected to maximize powder yield at least above 90%, and preferably above 97% [ 7 ]. In the case of the dependence of the powder yield on the inlet air temperature, its graphic image indicates the presence of a maximum ( Figure 3 ).…”

“…Therefore, in the production of functional food with a long shelf life, it becomes necessary to use dehydrated juices. In recent years, the demand for the development of food convenient for quick preparation, including instant food, has been growing steadily [ 7 ]. As a consequence, this trend has increased the demand for dehydrated juices.…”

“…Spray drying is a popular method for this purpose [ 7 , 8 , 9 , 10 , 11 ]; it minimizes losses of bioactive properties in dried plant products compared to other convection drying methods [ 11 ]. Previously, several researchers studied spray drying of chokeberry juice and extracts with various carriers [ 8 , 9 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ].…”

A Brief Overview of Spray Drying Technology and Its Potential in Food Applications

“…Regardless of the size of the spray drying equipment, only one man is recommended to be assigned to operate the dryer. Therefore, the labor component of the total cost becomes negligible as the size of the drying equipment increases [158]. In addition, spray drying also has a low maintenance requirement because it only has two moving parts: the main circulating fan and a high-pressure pump or centrifugal disc for atomization, and the technique naturally contributes itself to continuous operation [159].…”

“…When comparing spray dryers with other kinds of drying equipment, there is a critical capacity for a specific application [158]. However, the appropriate critical point varies for each type of application.…”