A Review on Stems Composition and Their Impact on Wine Quality

Abstract

Often blamed for bringing green aromas and astringency to wines, the use of stems is also empirically known to improve the aromatic complexity and freshness of some wines. Although applied in different wine-growing regions, stems use remains mainly experimental at a cellar level. Few studies have specifically focused on the compounds extracted from stems during fermentation and maceration and their potential impact on the must and wine matrices. We identified current knowledge on stem chemical composition and inventoried the compounds likely to be released during maceration to consider their theoretical impact. In addition, we investigated existing studies that examined the impact of either single stems or whole clusters on the wine quality. Many parameters influence stems’ effect on the wine, especially grape variety, stem state, how stems are incorporated, when they are added, and contact duration. Other rarely considered factors may also have an impact, including vintage and ripening conditions, which could affect the lignification of the stem.

Phenolic Composition of Grape Stems from Different Spanish Varieties and Vintages

“…Table 2 shows the results of the spectrophotometric analysis performed on all samples. The antioxidant activity and TPC values were in the same order than those obtained by other authors [9,14,24]. As it can be seen, there exist significant differences in antioxidant activity, TPC and TF content among grape stems from different varieties in each vintage.…”

“…Usually, grape stems are used as organic fertilizer, as feed for ruminants [7] or valorized through the production of ethanol and paper pulp [8]. However, in recent years, several studies have demonstrated that these by-products contain high concentrations of polyphenols, cellulose, hemicellulose and lignin [9][10][11], which is causing a growing interest in their use as bioactive phytochemicals [12,13]. For instance, Leal et al [14] found that stem extracts present antimicrobial activity, with high efficacy against ulcers produced by Gram-positive bacteria in foot wounds.…”

“…There exist a large variety of phenolic compounds belonging to different families identified in grape stems. Among them, caftaric and gallic acids are the most representative phenolic acids found in grape stems, trans-resveratrol and ε-viniferin the two main stilbenes, quercetin derivatives the main flavonols, catechin and epicatechin the most abundant flavanols, and malvidin-3glucoside and other malvidin derivatives are the anthocyanins most frequently identified in those by-products [9]. Despite this, Teixeira et al [23] found that the composition and concentration of polyphenols on grape stems depend on the grape variety, ripeness, climatic and geographical growing conditions and cultivation practices.…”

“…There exist research works that studied the influence of the grape variety on the phenolic composition of grape stem extracts [21,24,25], but there are few studies that afford the influence of a relevant factor such as the vintage in the polyphenolic composition of grape stems. Recently, Blackford et al [9] performed a compilation of the phenolic composition of different grape stems reported in the literature by different authors. In this work it is confirmed that there exist differences in the phenolic composition and antioxidant capacity among stems from different varieties and vintages.…”

High-Throughput Quantification of 32 Bioactive Antioxidant Phenolic Compounds in Grapes, Wines and Vinification Byproducts by LC–MS/MS

“…Functionally, the antioxidant phenolic compounds are classified into secondary metabolites, a class of plant-derived compounds with diverse chemical structures and functions, which are produced during the physiological growth of grapevines or as their response to various forms of environmental stress [ 8 , 9 , 10 ]. Their presence in grapevines is associated with the quality and authenticity of wines [ 11 , 12 , 13 ] along with a broad spectrum of bioactivities including antimicrobial [ 14 , 15 ], anticancer [ 16 , 17 , 18 ], antiaging [ 19 ], antiglycogenic [ 20 ] and cardiovascular system-protective [ 21 , 22 ] properties. During the last three decades, the biological activities of grapevine phenolic compounds have been extensively exploited, providing valuable information that has attributed their health-benefitting effects to their strong antioxidant properties.…”