Grape pomace: from waste to natural food supplement and biodiesel

The purpose of this study was to introduce a new source of antioxidants obtained from grape pomace as well as aronia and blueberry and engages them in preparation of a new yoghurt product in order to be last – longer and more beneficial for human health than the traditional one. Totally, grape pomaces from 4 varieties (Zupjanka, Prokupec, Kadinal and Vranec), as well as blueberry and aronia, were used. For the extraction of polyphenols, liquid-liquid extraction with ethanol/water/acetic acid was used in order to concentrate phenols and introduce them into the milk. Three different concentrates of each sample (18 in total) were applied on milk together with lactic bacteria in order to study the influence of polyphenols during the fermentation; as well as, 18 other extracts applied on milk after the fermentation (into the obtained yoghurt). The pH value of the newly generated yoghurts was analyzed during the fermentation and storage. All yoghurt samples containing polyphenolics applied before the fermentation, presented higher pH value compared to the control and samples with polyphenolics applied after fermentation.