Abstract
The effect of vinification techniques on phenolic compounds and antioxidant activity of wine lees are poorly understood. The present study investigated the antioxidant activity of white and red wine lees generated at early fermentation and during aging. In this study, the total phenol content (TPC), total tannin content (TTC), mean degree of polymerization (mDP), and antioxidant activities of five white and eight red wine lees samples from different vinification backgrounds were determined. The results showed that vinification techniques had a significant (p < 0.05) impact on total phenol and tannin content of the samples. White wine lees had high mDP content compared with red ones. Catechin (50–62%) and epicatechin contents were the predominant terminal units of polymeric proanthocyanidin extracted from examined samples. Epigallocatechin was the predominant extension unit of white wine lees, whereas epicatechin was the predominant compound in red wine marc. The ORAC (oxygen radical absorbance capacity) assay was strongly correlated with the DPPH (α,α-diphenyl-β-picrylhydrazyl) assay, and the results showed the strong antioxidant activities associated with red wine lees (PN > 35 mg Trolox/g FDM) (PN: Pinot noir lees; FDM: Freeze-dried Material). This study indicates that tannin is one of the major phenolic compounds available in wine lees that can be useful in human and animal health applications.
Highlights
75 million tonnes of grape were produced annually, of which 85% is used in the wine industry, and around 9 million tons of organic waste is generated [1]
Pinot Gris (PG) grapes may contain more anthocyanins and other phenolic compounds in their skins, as they are more coloured compared to C and Sauvignon Blanc (SB) varieties, and may contain more
Results from the present study show that Pinot Noir (PN) wine lees contained high phenolic compounds and antioxidant activities, and it is a useful source of antioxidants
Summary
75 million tonnes of grape were produced annually, of which 85% is used in the wine industry, and around 9 million tons of organic waste is generated [1] These waste materials are high in organic substances which are recognized as environmental pollutants, since they have high chemical oxygen demand (COD) and biological oxygen demand (BOD) [2]. Wine lees consist of dead yeast, yeast residues or particles precipitated at the bottom of wine tanks or barrels [5]. Current management of this waste, such as discarding to a landfill or spreading in vineyards as compost, were reported to have a negative impact on soil [6].
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