STABILITY, MICROBIOLOGICAL QUALITY, AND ANTIOXIDANT PROPERTIES OF EXTRACTS FROM BERRY FRUITS

The purpose of the study has been to determine the stability, microbiological quality, and antioxidant properties of extracts from the berry fruits of black chokeberry, American blueberry, and bilberry. In addition, the content of polyphenolic compounds in the extracts was analysed and the ratio of the content of anthocyanins to total phenols (the ACY/TP ratio) was determined. Extracts from the fruits of black chokeberry, American blueberry, and bilberry had different stability, microbiological quality, content of polyphenols, and ACY/TP ratio. The highest stability of anthocyanins and the highest ACY/TP ratio were determined in the extracts from bilberry, and the lowest ones appeared in the extracts from American blueberry. The stability of anthocyanins tended to decline during storage, either cooled or frozen. No bacteria were found in the berry fruit extracts although small contamination with microorganisms (yeast, mould) was detected. The highest content of polyphenolic compounds was determined in the extracts from black chokeberry and the lowest one in the extracts from American blueberry. The antioxidant activity of the extracts ranged from 1.99 to 2.41 TEAC mmol TR/100 g, and the antiradical activity varied from 84.91% to 86.30%. The applied extraction method with citric acid had a positive influence on the stability, microbiological quality, and antioxidant properties of the fruit extracts.