Physicochemical properties, antioxidant activity and stability of spray-driedpropolis
Felipe C. da Silva, Carmen S. Favaro-Trindade, Severino M. de Alencar, Marcelo Thomazini, and Julio C C. Balieiro
The aim of this study was to prepare and characterise alcohol-free propolis powder obtained using the spray-drying technique. The inlet air temperature that caused the least loss of phenolic compounds during spray drying was determined. A temperature of 120ºC was selected, and a sprayed dried sample of propolis was obtained. The sample was evaluated for moisture, water activity, hygroscopicity, solubility, thermal behaviour, morphology, stability of flavonoids and antioxidant activity whilst stored for 120 days at a temperature under 25oC. The sample displayed low hygroscopicity and water solubility. Its flavonoids remained stable during the storage period; however, the sample presented a tendency to agglomerate and it did not present a well-defined glass transition range. The spray drying process caused significant loss of phenolic compounds (approximately 30%) but antioxidant properties were retained. Thus, it was concluded that the spray-drying dehydration process may be used to obtain alcohol-free propolis powder that possesses antioxidant activity and stable flavonoids during storage.