 IVES 9 IVES Conference Series 9 New plant protein extracts as fining agents for red wines

New plant protein extracts as fining agents for red wines

Abstract

AIM: Quinoa (Chenopodium quinoa) is a non-allergenic pseudocereal with a high protein content. The aim of this work was to determine the phenolic fining ability of quinoa protein extracts (QP), and to compare them against commercial proteinaceous fining agents.

METHODS: Quinoa seeds of the variety Regalona-Baer, cultivated in Santa Rosa Experimental Center (Chillán, Chile) and red wine samples (Petit Verdot and Malbec) from the Maule Region of Chile were used for this study. QP were obtained by alkaline extraction and isoelectric precipitation. The protein content of quinoa samples and QP was determined by the Dumas method with a nitrogen to protein conversion factor of 5.85. SDS-PAGE profile of QP was analysed by electrophoresis, according to the Laemmli method (1). The fining efficacy of QP was evaluated at 20°C at different doses and contact times (48 and 96 h) and compared against three commercial fining agents of animal and vegetal origin (Vegefine, Vegecoll and Gelatin). The total tannin content in wines were measured spectrophotometrically by the methyl cellulose precipitable (MCP) tannin assay (2) and the Harbertson-Adams tannin assay (3). The total phenolics were quantified by the Folin-Ciocalteu assay (4). The anthocyanin content was determined according to the HPLC-DAD method OIV-MA-AS315-11 for the analysis of major anthocyanins in red and rosé wines.

RESULTS: QP showed a content of 60% protein with molecular weight distribution of ̴ 35 kDa, ̴ 22 kDa and ̴ 10 kDa. QP treatments significantly reduced turbidity, total tannin and total phenolics in Petit Verdot wine at the two doses tested (30 and 50 g/hL) and in a similar proportion than the commercial fining agents. For all fining agents it was observed that tannin content decreased more after 96 hours of contact time (11-16%) than after 48 hours (5-11%) of treatment. Like so, QP fining resulted in a significant reduction of the tannin content in Malbec fined wine (20-25%), more so than when using the commercial fining agents (3-10%). For both wines, the color of the fined samples (measured as malvidin-3-glucoside equivalent at 520 nm) was not significantly affected by the treatments with QPs.

CONCLUSIONS:

The results obtained suggest that QP could be an interesting alternative for wine fining with plant derived proteins; therefore, more studies on this subject are being performed.

DOI:

Publication date: September 10, 2021

Issue: Macrowine 2021

Type: Article

Authors

Liudis L. Pino

University of Talca,V. Felipe LAURIE, University of Talca

Contact the author

Keywords

wine, fining, plan ptoteins, quinoa, phenolics, tannin

Citation

Additives od aids? Evaluation of aroma compounds release from oenological tannins of different botanical origins.

Oenological tannins are products extracted from various botanical sources, such as mimosa,
acacia, oak gall, quebracho, chestnut and tara. The polyphenolic component is obtained through a solid-liquid extraction also using specific solvents, then removed by evaporation or freeze-drying. Tannins are employed in two phases of winemaking, during the pre-fermentative phase or during fining with different purposes such as modulate antioxidant activity, colour stabilization, bacteriostatic activity, protein stabilization and modulation of sensory properties. To date, the current regulatory framework is not very clear. In fact, the Codex Alimentarius classifies commercial tannins as “food additives” but also as
“processing aids”. The main distinction is that “additives” have a technological function in the final food, whereas “processing aids” do not. In this sense, oenological tannins, despite the technological treatments, could contain aromatic compounds of the botanical species they belong to and release them to the wine.

The vascular connections in grafted plants under examination

Aims: Decreasing longevity of vineyards due to the increase in the infection of different grapevine trunk diseases is a growing concern, and could be related to the quality of grafting. The main aim of this study was to evaluate the use of xylem hydraulic conductivity measurements as a potential indicator for the quality of vascular connections in

Gas chromatography-olfactometry characterization of corvina and corvinone young and aged wines

AIM AND METHODS: Corvina and Corvinone are the two main grape varieties used in the production of Valpolicella, Recioto and Amarone, top-quality red wines in north-eastern Italy. This work aimed at determining the aroma composition of Corvina and Corvinone experimental wines and identify the main aroma compounds contributing to the aroma characteristics of Corvina and Corvinone monovarietal wines. Five Corvina and five Corvinone wines were studied, the grapes coming from five different vineyards in Valpolicella. Volatile compounds were extracted by SPE and identified and quantified by gas chromatography-mass spectrometry (GC-MS), whereas their aroma impact was determined by gas chromatography- olfactometry (GC-O).RESULTS: Based on the GC-MS-O analysis, 95 odor zones were detected, from which 68 compounds were successfully identified. Using the criterion of a value higher than 30% in modified frequency (MF %), 51 compounds were selected and grouped according to odor similarity. Compounds with values below 30% were discarded.

New insights of translocation of smoke-related volatile phenols in vivo grapevines

The increasing frequency of wildfires in grape-growing regions is seen as a significant risk for the grape and wine industry.

The sensitivity to ABA affects the cross-talk between scion/rootstock in tolerant grapevines to drought stress

Drought caused by climate change has a dramatic incidence on the vineyard. Despite employing specific rootstocks tolerant to drought like 110 Richter, the vineyard continues to experience various losses, revealing the importance of the scion cultivar in the adaptation to drought stress. In this regard, Merlot, a widely cultivated grapevine, exhibited reduced drought tolerance compared to less cultivated varieties like Callet, a local cultivar originating from the Balearic Islands that demonstrated greater resilience to drought. Therefore, understanding the drought stress response in both cultivars and the cross-talk between scion and rootstock is key to unveiling possible differences that could affect to the adaptation to drought in vineyard.