The aim of the present study was to analyse and compare camel milk powder quality and functional properties produced with spray-drying and freeze-drying techniques. Freeze-drying is recognized as an advanced method for the production of high-quality dried products, but it has been a costly process for production of camel milk powder. Spray-drying and freeze-drying of camel’s milk demonstrated that the nutritional characteristics of this product basically remained unchanged compared to fresh milk. The differences were found analysing flowability, solubility and hygroscopicity of camel milk powder samples obtained with freeze-drying and spray-drying technique. Analysed quality indices of camel milk demonstrated that spray-drying has lower impact on camel milk powder physical properties in comparison with freeze-drying.

Honey is a naturally supersaturated sugar solution, which tends to crystallize. The crystallization of honey can lead to unwanted fermentation that can have a negative impact to honey quality. The production of honey powder could be an alternative method to prevent honey from fermentation. Honey powder could be used as alternative substitute to liquid honey that would allow to use this product more widely in the food industry. α-amylase activity is one of the most important parameters to evaluate the quality of honey. The aim of this study was to investigate the effect of freeze-drying and spray-drying on honey α-amylase activity. Detection of α-amylase activity was carried out by spectrophotometric method. High-performance liquid chromatography was used to determine the content of hydroxymethylfurfural in the powders. The obtained results showed that both drying methods had a negative impact to the enzyme activity in the samples. The lowest activity of α-amylase (8.3 DN) was measured in the spray-dried honey powder. Concentration of hydroxymethylfurfural (HMF) in the powders did not exceed required concentration 40 mg kgE−1.

Kvass is an aromatic soft drink which in a form of powder could be used in dairy or bakery products, or sugar confectionary to expand the diversity of flavours. Spray drying is one of the techniques used for producing powders; however, liquids with high sugar content become sticky during drying process and need additional drying aids to increase glass transition temperature and improve powder stability. The aim of this research was to evaluate the characteristics of dry naturally fermented kvass. Maltodextrin was used in 50, 40 and 25% quantity to kvass dry matter in order to aid the spray drying of naturally fermented non-pasteurised, non-filtered bread kvass. Spray drying of 8 l naturally fermented kvass returned approximately 500 g dry naturally fermented kvass powder with a light brown colour, a pronounced aroma of rye bread and moisture content of 7 ± 0.1%. Microstructure analysis of the spray dried naturally fermented kvass showed irregularly spherical shaped particles, having many shrinkages, breakages and dents on the surface in general. Total viable microorganism count in dry naturally fermented kvass powder was within the recommended levels, traces of lactic acid bacteria were found in all samples. The presence of Bacillus amyloliquefaciens was established in dry naturally fermented kvass powders, with possible contamination from spray dryer.