Effective assay for olive vinegar production from olive oil mill wastewaters

In this work, an effective and simple approach for vinegar production from olive oil press-mill wastewaters (OMW) is presented. Effects of sterilization and yeast presence on the acetic acid production were investigated. Sugar addition and inoculum of selected yeast starter have been crucial for a satisfactory acidification. In the obtained olive vinegar, the pH and total acidity were 2.92 and 5.6%, respectively. A considerable high level of ash (2%) and total phenols (3600 mg/L as GAE) characterized olive vinegar, in comparison with samples of apple, wine and balsamic commercial vinegars. Moreover, a high presence of hydroxytyrosol (1019 mg/L) was obtained. This abundant presence of antioxidants makes olive vinegar a promising nutraceutical and environmentally-friendly product, based upon a waste material such as OMW.