The Evolution of Polyphenols from Grapes to Wines

Abstract

Polyphenols play an important role in the quality of wines, due to their contribution to the wine sensory properties: color, astringency and bitterness. They act as antioxidants, having positive role in human health. They can be divided into non-flavonoid (hydroxybenzoic and hydroxycinnamic acids and stilbenes) and flavonoid compounds (anthocyanins, flavan-3-ols and flavonols). Anthocyanins are responsible for the color of red grapes and wines, hydroxycinnamic and hydroxybenzoic acids act as copigments, stilbenes as antioxidants and the flavan-3-ols are mainly responsible for the astringency, bitterness and structure of wines, being involved also in the color stabilization during aging. This chapter will focus on the chemical structures of the main polyphenols, their identification and quantification in grapes and wines by advanced analytical techniques, highlighting also the maceration and aging impact on the polyphenols evolution. The factors influencing the phenolic accumulation in grapes are also reviewed, emphasizing as well the relationship between phenolic content in grapes versus wine. Polyphenolic changes during the wine making process are highlighted along with the main polyphenol extraction methods and analysis techniques. This research will contribute to the improvement in the knowledge of polyphenols: their presence in grapes, the relationship with wine quality and the influence of the external factors on their evolution.

An Approach of the Madeira Wine Chemistry

“…They are formed biogenetically from either the shikimate/phenylpropanoid and/or 'polyketide' acetate/malonate pathway, resulting in monomeric, polymeric phenols and polyphenols [107]. Their concentrations in wines are influenced by the technological practices, location (e.g., altitude, geological features, soil type, sunlight exposure), climate, ripening stage, and viticultural practices [108,109]. Polyphenols can be classified into two main groups, namely flavonoids (e.g., flavonols, flavones, isoflavones, flavanones, flavanols, anthocyanidins, procyanidins) and non-flavonoids (e.g., phenolic acids, stilbenes, lignans) [110].…”

“…Perhaps, the white wines showed a lower concentration of polyphenols when compared with the red ones, and in turn, their content in caftaric acid is higher. Also, hydroxycinnamic acids and their tartaric esters represent the main class of non-flavonoid phenolics in red wines, whereas in white wines, they are are predominant [108,113]. From the flavonoids, the anthocyanins are responsible for the characteristic red color of grapes and wines, whereas the flavan-3-ols are most related to the astringency, bitterness, and structure of wines [108].…”

Accumulation of Phenolic Compounds and Antioxidant Capacity during Berry Development in Black ‘Isabel’ Grape (Vitis vinifera L. x Vitis labrusca L.)

“…Endogenous sugar increases the synthesis of anthocyanin, a phenomenon directly and closely related to peonidin derivatives and the other phenolic compounds present in grape skin [26]. Anthocyanin concentrations increase during ripening until reaching a maximum value, after which the concentration decreases, particularly in over-ripe grapes [33]. The increasing trend in anthocyanin content after veraison (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26) observed in the present study was similar to that in the sugar increase and acid decrease in the same grape variety ('Isabel', black) picked from the same grapevine the same number of days after full bloom (DAFB).…”

Polyphenol Fingerprinting Approaches in Wine Traceability and Authenticity: Assessment and Implications of Red Wines

“…The term derives from their capacity to undertake hydrolysis under acidic conditions, which will cause the release of anthocyanidin pigments [20]. Furthermore, the intermediate unstable carbo-cations tend to combine with proteins or polysaccharides to produce stable complexes [35]. By coupling with the saliva proteins, tannins highlight specific astringency and bitterness sensations in red wines; at the same time, they participate in stabilizing the color as a result Flavanols may form oligomers and polymers, which are called condensed tannins or proanthocyanidins [24].…”

“…While condensed tannins are considered to be grape-derived, the tannins released by the wood during aging in barrels are called hydrolysable tannins or ellagitannins (ellagic acid is produced through their hydrolysis) [35].…”