Characterization of Bioactive Compounds in Lees from New Zealand Wines with Different Vinification Backgrounds

Potential bioactive peptides obtained after in vitro gastrointestinal digestion of wine lees from sequential fermentations

The biotechnological reuse of winery by-products has great potential to increase the value and sustainability of the wine industry. Recent studies revealed that yeast biomass can be an exciting source of bioactive peptides with possible benefits for human health, and its incorporation in plant-based foods is considered innovative and sustainable. In this study, we aimed to identify, through in silico analyses, potential bioactive peptides from yeast extracts after in vitro digestion. Wine lees from a non-Saccharomyces oenological yeast, Starmerella bacillaris FRI751, Saccharomyces cerevisiae EC1118, and sequential fermentation performed with both strains (SEQ) were recovered in a synthetic must. Cellular pellets were enzymatically treated with zymolyase, and the yeast extracts were submitted to in vitro gastrointestinal digestions. LC-MS/MS sequenced the hydrolyzed peptides, and their potential bioactivity was inferred. S. bacillaris FRI751 fermentation showed 132 peptide sequences, S. cerevisiae EC1118 60, SEQ 89. A total of 243 unique peptide sequences were identified across the groups. Furthermore, based on the peptide sequence, the FRI751 extract showed the highest potential antihypertensive with 275 bioactive fragments. Other bioactivities, such as antimicrobial and immunomodulatory, were also identified in all yeast extracts. A potential antiobesity bioactive peptide VVP was identified only in the yeast extract from S. bacillaris single strain. The wine lees from S. bacillaris single strain and SEQ fermentation are a richer source of potential bioactive peptides than those from S. cerevisiae fermentation. This study opens new possibilities in the valorization of winemaking by-products.

Enhancing Anthocyanin Extraction from Wine Lees: A Comprehensive Ultrasound-Assisted Optimization Study

Wine lees, an important by-product of the wine industry, pose a major environmental problem due to the enormous quantities of solid-liquid waste that are discarded annually without defined applications. In this study, the optimization of a method based on a Box-Behnken design with surface response has been carried out to obtain extracts with high anthocyanin content and potent antioxidant activity. Six variables have been considered: %EtOH, temperature, amplitude, cycle, pH, and ratio. The developed method exhibited important repeatability properties and intermediate precision, with less than 5% CV being achieved. Furthermore, these novel methods were successfully applied to diverse wine lees samples sourced from Cabernet Sauvignon and Syrah varieties (Vitis vinifera), resulting in extracts enriched with significant anthocyanin content and noteworthy antioxidant activity. Additionally, this study evaluated the influence of grape variety, fermentation type (alcoholic or malolactic), and sample treatment on anthocyanin content and antioxidant activity, providing valuable insights for further research and application in various sectors. The potential applications of these high-quality extracts extend beyond the winemaking industry, holding promise for fields like medicine, pharmaceuticals, and nutraceuticals, thus promoting a circular economy and mitigating environmental contamination.

Preparative Fractionation of Phenolic Compounds and Isolation of an Enriched Flavonol Fraction from Winemaking Industry By-Products by High-Performance Counter-Current Chromatography

High-performance counter-current chromatography (HPCCC) was used as a tool for the isolation and fractionation of phenolic compounds (PCs) in extracts from wine lees (WL) and grape pomace (GP). The biphasic solvent systems applied for HPCCC separation were n-butanol:methyl tert-butyl ether:acetonitrile:water (3:1:1:5) with 0.1% trifluoroacetic acid (TFA) and n-hexane:ethyl acetate:methanol:water (1:5:1:5). After refining the ethanol:water extracts of GP and WL by-products by ethyl acetate extraction, the latter system yielded an enriched fraction of the minor family of flavonols. Recoveries of 112.9 and 105.9 mg of purified flavonols (myricetin, quercetin, isorhamnetin, and kaempferol) in GP and WL, respectively, from 500 mg of ethyl acetate extract (equivalent to 10 g of by-product) were obtained. The HPCCC fractionation and concentration capabilities were also exploited for the characterization and tentative identification of constitutive PCs by ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS). In addition to the isolation of the enriched flavonol fraction, a total of 57 PCs in both matrixes were identified, 12 of which were reported for the first time in WL and/or GP. The application of HPCCC to GP and WL extracts may be a powerful approach to isolate large amounts of minor PCs. The composition of the isolated fraction demonstrated quantitative differences in the individual compound composition of GP and WL, supporting the potential exploitation of these matrixes as sources of specific flavonols for technological applications.

Studies on the Effect of Oxidation on Bioactivity of Phenolics and Wine Lees Extracts

It is expected that any processing and handling of lees (e.g., drying, storage or removal of residual alcohol using various concentration techniques) will expose the material to oxidation and the consequences of oxidation on the biological activity of the lees and the lees extracts are unknown. The effects of oxidation (using horseradish peroxidase and hydrogen peroxide model system) on phenolic composition and their antioxidant and antimicrobial activities were investigated in (i) a flavonoid model system composed of catechin and grape seed tannin (Cat:GST) extracts at various ratios and (ii) in Pinot noir (PN) and Riesling (RL) wine lees samples. For the flavonoid model, oxidation had a minor or no impact on total phenol content but increased (p < 0.05) total tannin content from approximately 145 to 1200 µg epicatechin equivalent/mL. An opposite observation was found in the PN lees samples where oxidation reduced (p < 0.05) the total phenol content (TPC) by approximately 10 mg GAE/g dry matter (DM) lees. The mean degree of the polymerization (mDP) values of the oxidized flavonoid model samples ranged from 15 to 30. The Cat:GST ratio and interaction of the Cat:GST ratio with oxidation were found significantly to affect the mDP values of the flavonoid model samples (p < 0.05). Oxidation increased the mDP values in all oxidized flavonoid model samples except for Cat:GST 0:100. The mDP values of the PN lees samples ranged from 7 to 11 and remained the same after oxidation. There was no significant reduction in the antioxidant activities (DPPH and ORAC) of the model and wine lees after oxidation except the PN1 lees sample (decreased from 3.5 to 2.8 mg Trolox equivalent/g DM extracts). In addition, no correlation was observed between mDP (approximately 10 to 30) and DPPH (0.09) and ORAC assay (-0.22), which indicates that the higher mDP resulted in a poor ability to scavenge DPPH· and AAPH· free radicals. Antimicrobial activities of the flavonoid model were found to be improved after the oxidation treatment against S. aureus and E. coli with minimum inhibition concentration (MIC) of 1.56 and 0.39 mg/mL. This may indicate that new compounds were formed during the oxidation treatment, and these compounds showed more effective microbicidal activity. LC-MS work is required in the future to identify the compounds that are newly formed during the oxidation of the lees.

The (Poly)phenolic Profile of Separate Winery By-Products Reveals Potential Antioxidant Synergies

The by-products of grapes (Vitis vinifera L.) in the winemaking process present a diverse phytochemical profile of (poly)phenols, essentially represented by phenolic acids, flavonoids, and stilbenes, which have health benefits. In winemaking, solid (grape stems and pomace) and semisolid (wine lees) by-products are generated, negatively impacting the sustainability of the agro-food activity and the local environment. Although information on the phytochemical profile of grape stems and pomace has been reported, especially information concerning (poly)phenols, research on wine lees is necessary to take advantage of the compositional traits of this residue. So, in the present work, an updated, in-depth comparison of the (poly)phenolic profiles of these three resulting matrices in the agro-food industry has been carried out to provide new knowledge and interesting data on the action of yeast and lactic acid bacteria (LAB) metabolism in the diversification of phenolic composition; additionally, we extract complementarities for the possible joint application of the three residues. The phytochemical analysis of the extracts was carried out using HPLC-PDA-ESI-MSn. The (poly)phenolic profiles of the residues showed significant discrepancies. The results obtained showed that the greatest diversity of (poly)phenols was found in the stems of the grapes, followed closely by the lees. Through technological insights, it has been suggested that yeasts and LAB, responsible for the fermentation of must, might play a key role in the transformation of phenolic compounds. This would provide new molecules with specific bioavailability and bioactivity features, which might interact with different molecular targets and, consequently, improve the biological potential of these underexploited residues.