Physicochemical properties, antioxidant activity and stability of spray-dried propolis

Abstract

Summary 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 120∫C was s elected, and a sprayed dried sample of propolis was obtained. The sample was evaluated for moisture, water activity, hygroscopicity, s olubility, thermal behaviour, morphology, stability of flavonoids and antioxidant activity whilst stored for 120 days at a temperature u nder 25 o C. The sample displayed low hygroscopicity and water solubility. Its flavonoids remained stable during the storage period; however, thesample presented a tendency to agglomerate and it did not present a well -defined glass transition range. The spray drying process cause d significant loss of phenolic compounds (approximately 30%) but antioxidant properties were retained. Thus, it was concluded that the spra y-drying dehydration process may be used to obtain alcohol -free propolis powder thatpossesses antioxidantactivity and stable flavonoids during storage.