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Introduction Dracocephalum moldavica L. is an annual plant with blue or white flowers and fragrant leaves which belongs to the family of Lamiaceae with the height of up to 80 cm. This plant is native to Central Asia and is accepted in Central and Eastern Europe. In Iran, it is mainly grown in the province of West Azarbaijan and the Alborz Mountains. The essential oils and extracts derived from the secondary metabolisms which are mainly used in the pharmaceutical industry, dietary, cosmetic, flavoring and also as tea and beverage with sugar or honey. The liquid extract of the herb contains a high percentage of water, which should evaporate to increase shelf-life, easy transport, handling and storage, the ease of standardization and preservation of the product quality. On the other hand, the active compounds of the extracts are affected by temperature, oxygen, light and enzymes. Therefore, because of the uses and benefits of herbal extracts, they need to be dried by a practical and effective method like spray drying. In literature still there are no studies taking into account to the comparisons between RSM and TOPSIS as two important optimization methods. So, as the main objective of the present work, the effects of moisture content, drying performance, total phenol content, total flavonoid content and antioxidant activity have been surveyed. Finally, the optimal point of each process variable was presented by two optimization methods. Materials and Methods Aerial parts of Moldavian balm plant were cleaned and drying of plant was carried out under shade and thin layer conditions. The extraction of Moldavian balm was obtained by maceration method using ethanol 50 % (v/v), plant to solvent ratio of 1/10 (w/v). After 48h, the extract was concentrated in a rotary evaporator (Buchi Rotavapor R-205, Switzerland) to obtain a solid concentration of 6%. The used carrier was: Maltodextrin and apple pectin. Different ratios of carrier were prepared, then the ratio was added to distilled water and stirred by a magnetic stirrer. Finally, the solution was mixed with extract. The drying of Moldavian Balm plant extract was performed using a spray-dryer (Büchi B-191, Switzerland) with co-current flow regime. The powders provided by the spray drying were stored in refrigerator until they were needed for the experiment. Results and Discussion The results of variance analysis showed that the Box-Behnken design with the second-order model has led to the meaningfulness of the model, insignificant of the Lack of Fit and the appropriate correlation coefficient for each of the responses. A total number of 15 experiments were conducted to investigate the effect of process variables such as inlet air temperature, compressed air flow rate and concentration of carriers on moisture content, drying performance, total phenolic content, total flavonoid content and antioxidant activity of Moldavian balm powder. Inlet air temperature and compressed air flow rate had the most significant effect on moisture content and drying performance, while Chemical properties of the powder affected by changing the concentration of carriers. Optimization parameters of the spray drying process was performed using surface response and TOPSIS methods. The optimum predicted conditions in the response surface method and TOPSIS method were obtained at inlet air temperature, compressed air flow rate and concentration of carrier (152.5-150°C), (8.046-7.5 lit min-1) and 20%, respectively. Conclusion By comparing two methods, it can be concluded that although they could provide the same optimum points, the RSM is more efficient. Because RSM offers a mathematical model that can be used at any desired point of variables to predict the output quantities as well as describing the process trend, while TOPSIS method is unable to predict the process trend and only provides the ranking of alternatives.

Introduction: In the recent years, attention to the use of probiotic drugs and probiotic food products, due to probiotic’s functional and health properties has been increased. The storage and the viability of the probiotics in the products and passing through the gastrointestinal tract was always a big challenge. Drying is one of the functional and important choices that can be used for stabilizing microbial species and makes the bacterial usage easy. Among different microencapsulation methods, spray drying is one of the important drying methods that can be used in industrial scale and size. Optimizing the effective parameters on the cultivation and separation of probiotic bacteria, the most important and challenging parameters of spray drying that have influence on probiotic products, and choose of the best wall materials for the cores, are the most important and challenging factors that are necessary for optimizing the microencapsulation in industrial scale. In this review article, the factors affecting the survival and resistance of bacteria in the stage before entering the spray dryer and the factors affecting the survival of probiotic bacteria during the drying stage are discussed. In addition, the important criteria for selecting microfiber wall materials and the tests that are often performed on probiotic microfiber resulting from spray drying have been examined.

The NLCs are potent carriers for lipophilic bioactive compounds. In this study, the NLC:maltodextrin (6:10) solution at the inlet temperatures of 110 or 180 °C, and the feed flow rate of 5 or 15 mL/min was spray-dried and the powders characteristics were evaluated. The SEM micrographs showed the particle morphologies of hollow spheroids with smooth surfaces. The powder production yields as high as 66% was achieved. The sizes of NLC particles after the redispersion of the spray-dried powders shifted to higher amounts [from 57.3 nm (in the biggest size before drying) to 93.7 nm (in the biggest size after drying)], but were below the acceptable size of NLC systems. The measurement of flowability indices such as Carr’s compressibility index (in average 16.21), Hausner ratio (in average 1.20), and angle of repose (31-42°) showed that the samples were categorized as the powders with good flowability. The results of this study revealed that NLC systems can be successfully spray-dried by using maltodextrin as the excipient without any drastic changes in the particle size. [ABSTRACT FROM AUTHOR]

In this study, the effect of different drying methods on cellulosic nanofibers and resulting composites investigated. Four methods were examined to dry nanofibrillated cellulose suspensions: air drying, oven drying, spray-drying and freeze drying. The particle size and morphology of the CNFs were determined via dynamic light scattering, scanning electron microscopy, and morphological analysis. Freeze drying formed ribbon-like structures of the CNFs with nano-scale thicknesses. Width and length were observed in tens to hundreds of microns. Spray-drying formed particles with a size distribution ranging from nanometer to several microns. Spray-drying is proposed as a technically suitable manufacturing process to dry CNF suspensions not only with dimension in nano range but also improving mechanical properties of poly (lactic acid) based composites.

In this study, the effects of some processing parameters on drying yield, moisture content, solubility and bulk density of spray dried cornelian cherry (Cournus mas L.) juice powders were investigated. A pilot-scale spray dryer was employed for the spray drying process and maltodextrin and gum Arabic were used as carrier agent. Experimental design involved the use of Box-behnken design and response surface statistical method. Independent variables were inlet air temperature (110, 140, and 170 C), concentration of drying aids (0, 7.5, and 15 %) and feed flow rate (6, 9, and 12 %). Results show that increasing in concentration of drying aids, increases drying yield and the solubility and reduces the moisture content and bulk density of powder; also increasing in inlet air temperature, increases drying yield and reduce solubility, moisture content and bulk density of powder. Optimization carried out using response surface methodology and optimum conditions were inlet air temperature of 140 oC, maltodextrin concentration of 7% and feed flow rate of 9%. [ABSTRACT FROM AUTHOR]