PRODUCTION OF A FUNCTIONAL BEVERAGE FROM WINEMAKING BY-PRODUCTS: A NEW WAY OF VALORISATION

Abstract

In the challenge of transforming waste into useful products that can be re-used in a circular economy perspective, winery by-products can be considered as a source of potentially bioactive molecules such as polyphenols. The wine industry generates each year 20 million tons of by-products. Kombucha fermentation is an ancestral process which allow to increase the biological properties of tea by the action of a microbial consortium formed by yeasts and bacteria called SCOBY. It belongs to the field of healthy food for which the interest of consumers is growing. The objective of this work was to propose a new functional beverage made from winemaking by-products fermented by a Kombucha SCOBY.

In a preliminary step, 2 types of by products were evaluated for Kombucha fermentation, wine lees and grape pomaces in order to assess their ability to ferment. Then the work was focused on grape pomaces originated from red winemaking. Several parameters were varied during the fermentation process: temperature, pomace concentration, sugar concentration, temperature and duration. The fermentation kinetics and final composition of grape Kombucha were monitored. Several biological activities were assessed in vitro at the beginning and at the end of fermentation: antioxydant, antidiabetic and anti-inflammatory. Depending on their physico-chemical and biological characteristics, some of the pomace Kombucha beverages were submitted to a sensory evaluation.

For all fermentation conditions the biological activities were increased, at least by a factor 2, at the end of fermentation compared to the non-fermented grape pomaces infusions. However according to their concentrations in sugar and total acidity, the grape pomace Kombuchas were not equally appreciated by the panellists. A majority of them preferred the Kombucha flavoured with natural fruity aroma.

This work confirmed the feasibility of making a grape pomace Kombucha beverage. Even if the kombucha fermentation improved the biological activities of this new beverage, results showed that there is no significant impact of the tested processing parameters on the biological activities in vitro. This new functional beverage consists into a new way of winemaking by-products valorisation. As for future perspectives, the organoleptic aspect must be improved.