Preliminary Results on Aroma Compounds Recovery from Wine Lees ^†

Valorization of agro-industrial wastes and by-products to obtain new value-added products is one of the most important goals of the scientific research for the development of the sustainable bioeconomy. According to the statistics of The Food and Agriculture Organization (FAO) of the United Nations, grape is the largest fruit crop worldwide. Wine industry disposes large volumes of wastes which represent 20–30% of total wine production including wastewater and solid organic by-products as wine lees and grape pomace composed of stalks, skins and seeds [1]. Wine lees are the residue that forms at the bottom of the vessel containing wine during the storage, represent 2–6% of the total volume of wine produced and contain about 62.9% (w/w) water, 5.7% (w/w) ethanol and 31.4% (w/w) solids on a dry basis [2]. Biorefinery of wine lees produces mainly ethanol, antioxidants and tartaric acid. The solid fraction contains high concentrations of macronutrients, yeast cells with polyphenolic compounds and proteins [3]. Wine lees also contain natural essential oils with complex composition mainly fatty acid esters produced during the fermentative process, when metabolites from yeast after bioconversion of grape juice are released and contribute to wine flavor and aroma [4]. The purpose of present research is the wine lees valorization for the recovery of volatile compounds responsible for wine aroma, one of the most important indicators of wine quality and potential ingredients for new additives with various applications. Several preliminary experiments were performed using azeotrope distillation with Clevenger apparatus for light oil extraction. The most important aroma compounds known as “cognac oil” (C8-C12 fatty acid ethyl esters) were obtained from red wine lees by a cascade hydrodistillation process, identified and quantified to a 0.99% total concentration with GC-MS analysis.