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Green Extraction of Nutritional and Antioxidant Valuable Compounds from Wine By-Products
Published in Francisco J. Barba, Elena Roselló-Soto, Mladen Brnčić, Jose M. Lorenzo, Green Extraction and Valorization of By-Products from Food Processing, 2019
Francisco J. Barba, Belén Gómez, Gabriela I. Denoya, Mladen Brnčić, Suzana Rimac-Brnčić, Jose M. Lorenzo, Andrés Moreno
Lees are yeast residues collected after different stages of the winemaking process, such as filtration, centrifugation, or even deposits in wine vessels. The red wine yeast lees involve around 12 kg of pigments per ton (Hogervorst et al., 2017). In fact, these by-products have been characterized for their rich composition consisting of yeasts, tartaric acid, polyphenols, and inorganic compounds. Moreover, lees incorporate enzymes that can change polyphenols into simple phenolic components (Vattem & Shetty, 2003), as well as are usually employed in the aging process for improving the wine quality by reducing bitterness (Tao et al., 2014). With the aim of incrementing its economic value, wine lees are being used as raw material for the recovery of polyphenols. For instance, Tao et al. (2014) compared the extraction of antioxidant compounds from wine lees using UAE and conventional maceration, finding an approximate recovery percentage of 20% lower in the second case, for both the total phenolic content (58.76 vs. 49.04 mg/g) and total anthocyanin concentration (6.69 vs. 5.55 mg/g). Particularly, the optimal UAE conditions for the highest total phenolic content, considering the sonication time, temperature, liquid–solid ratio, and ethanol proportion were 25 min, 60 °C, 60:1, and ~44%, respectively. While the maximum anthocyanin yield was observed after selecting these values for these parameters: 36.3 min, 59.9 °C, and 51.5% of ethanol concentration.
Production of Wines and Spirits
Published in Nduka Okafor, Benedict C. Okeke, Modern Industrial Microbiology and Biotechnology, 2017
Nduka Okafor, Benedict C. Okeke
The fermentation is usually over in three to five days. At this time, ‘pomace’ formed from grape skins (in red wines) will have risen to the top of the brew. As has been indicated earlier for white wine, the skin is not allowed in the fermentation. At the end of this fermentation, the wine is allowed to flow through a perforated bottom, if pomace had been allowed to form. When the pomace has been separated from wine and the fermentation is complete or stopped, the next stage is ‘racking’. The wine is allowed to stand until a major portion of the yeast cells and other fine suspended materials have collected at the bottom of the container as sediment or ‘lees’. It is then ‘racked’, a process, in which the clear wine is carefully pumped or siphoned off without disturbing the lees.
Anaerobic co-digestion of winery waste: comparative assessment of grape marc waste and lees derived from organic crops
Published in Environmental Technology, 2021
J. Hungría, J. A. Siles, A. F. Chica, A. Gil, M. A. Martín
Grape marc waste is produced during the pressing of grapes, which is the first step of the winemaking process. After the liquid (must) is separated from the solid fraction (grape marc waste), the must is stored for clarification and disinfected with sulfide dioxide. The next stage is fermentation, where another waste called lees is generated. Grape marc waste is stacked in the winery until the distillery collects the residues to obtain ethanol, while lees are stored in tanks to extract mainly ethanol and tartrate acid [3].