Development of new non-dairy beverages from Mediterranean fruit juices fermented with water kefir microorganisms

The aim of this work was to explore the use of several Mediterranean fruit juices as fermentable substratesto develop new non-dairy fermented beverages. Microbiological, chemical and sensory features ofkefir-like beverages obtained after the fermentation of juices extracted from fruits cultivated in Sicily(southern Italy) with water kefir microorganisms were investigated. Results indicated that both lacticacid bacteria and yeasts were able to develop in the fruit juices tested, but the highest levels wereregistered with prickly pear fruit juice. All fruit juices underwent a lactic fermentation, since a lactic acidcontent was detected in the resulting kefir-like beverages. Except kiwifruit and quince based kefirs, totaltitratable acidity increased for the other experimental products. A general decrease of the soluble solidcontent and an increase of the number of volatile organic compounds (VOCs) was also observed afterfermentation. As expected, the fermentation increased the concentration of alcohols. The mainfermentation in KLBs resulted to be yeast-based. Kiwifruit and pomegranate juices possessed a highantioxidant activity. Esters compounds were present at higher amount after the fermentation, especiallyin grape, pomegranate and quince. Aldehydes showed an opposite trend. Changes in colour attributeswere registered as noticeable at human perception scale. The overall quality evaluation indicated that,among the Mediterranean fruit juices tested, apple and grape beverages were the products mostlyappreciated by the tasters. Therefore, these findings support the possibility to develop fruit-based kefirlikebeverages with high added value and functional properties.