Alternative application to overcome caking problem for pomegranate juice and sage extract powder production

Spray drying is a widely used technique for drying liquids and obtaining powdered products. The short exposure of the product to high temperatures, ease of production, economic feasibility and relatively low infrastructure costs have played a role in the wide-scale use of this technique. Although the products have many advantages in terms of production method, the physicochemical properties of the products can show large variations depending on environmental factors. Caking is one of the most common problems encountered during the storage of powdered products, altering the technological properties of the product and limiting its use. In this study, the use of anti-caking agents and agglomeration applications in fluidized bed dryer were aimed separately to eliminate the caking problem, which negatively affects the quality characteristics of powdered products, and to improve the flow properties of the product. Spray-dried powders of sage extract and pomegranate juice were selected as model foods, since they have high caking tendency, and both anti-caking agent dosage rates and agglomeration conditions were attempted to be optimized for each product. Silicon dioxide, tri-calcium phosphate and calcium carbonate were selected as anti-caking agents in the study and a mixture design was used to optimize the optimum combination of these agents. The maximum anti-caking agent usage rate was fixed at 2% due to legal regulations. The impact of the anti-caking agents and usage rates tested in the study on the target properties of both products, specifically the degree of caking and flow properties, was found to be insignificant in terms of the optimization models tested and no difference between the anti-caking agents used could be determined in terms of their effectiveness. For this reason, silica was preferred as an anti-caking agent in the study, considering the raw material costs. In the fluidized bed dryer experiments, the agglomeration of sage extract powders showed only a temperature-dependent change, and agglomeration could not be achieved with the tested gum Arabic and maltodextrin (DE 18) solutions as binder liquids. Agglomeration could be achieved at a drying temperature of 75 °C using only water as binder liquid. The optimum agglomeration conditions for pomegranate juice powders were determined to be 78.5 °C drying temperature and 25% gum Arabic solution as the binding liquid according to the central composite experimental design. In the analyses carried out, the degree of caking was determined to be 35.6%, 34.8% and 7.6% for spray-dried, anti-caking agent added and agglomerated sage extract powders, respectively. It was found that the use of agglomeration had a 5-fold and decreasing effect on the degree of caking, while the use of anti-caking agent had no significant effect on the dosages tested in the study. The degree of caking was determined to be 71.7%, 46.5% and 17.9% for spray-dried, anti-caking agent added and agglomerated pomegranate juice powders, and it was determined that the use of anti-caking agent and agglomeration application reduced the caking tendency of the products by approximately 1.5 and 4 times, respectively. In terms of flow properties, it was found that the processes applied were only significantly effective in improving the flow properties of pomegranate juice powder. In addition, as a result of the processes carried out, it was determined that the agglomerated samples were less affected by external factors and accordingly showed a less hygroscopic structure during the storage period and the bioactive components were better preserved. According to the results obtained within the scope of the thesis, agglomeration application in fluidized bed dryer was found to be more successful in preventing the degree of caking on the tested products compared to other methods. With regard to the stability of the products, it was assessed that storage at low temperatures would be more appropriate.