IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 HPLC and SEC analysis on the flavonoids and the skin cell wall material of Merlot berries reveals new insights into the study of the phenolic maturity

HPLC and SEC analysis on the flavonoids and the skin cell wall material of Merlot berries reveals new insights into the study of the phenolic maturity


Anthocyanins and tannins contribute to important sensorial traits of red wines, such as color and mouthfeel attributes. Despite the evolution of flavonoids during berry ripening has been extensively studied and the properties of skin and flesh cell wall material (CWM) to bind tannins were described, the mechanism determining the reduction of unpleasant astringency in the last phases of ripening remained uncertain. In this regard, the present research was aimed to better understand the factors involved in the phenolic maturity by a detailed evaluation of the flavonoid characteristics and the CWM properties, in the last weeks before harvest and at harvest. The study was conducted in 2014 and 2015 in a Merlot vineyard located in the hills near Bologna (north of Italy). The analysis of flavonoids and skin CWM was performed on berries sampled 20 and 10 days before harvest and at harvest. Exhaustive extractions were conducted to analyze total anthocyanins and tannins (skin and seed separately), while a model hydroalcoholic solution was used for their extractable portion. Moreover, binding reactions between the CWM and an enological seed tannin were performed to evaluate the magnitude of tannin precipitation and the composition of the  tannins remained in solution.HPLC analysis showed the increase of total and extractable anthocyanins during ripening, while no change was found in the concentration, composition and mean degree of polymerization (mDP) of skin and seed tannins. Also, the composition of CWM did not change significantly, but the tendency of proteins to increase until the harvest was noticed in both years. Moreover, CWM bound increasing quantity of the enological seed tannin during ripening, favoring, in particular, the precipitation of the tannins with higher mDP and of the galloilated forms, which are reported to be the compounds more involved in the perception of unpleasant astringency. The analysis performed by SEC confirmed that CWM bound preferentially the tannins of high molecular mass (MM), while lower amounts of medium MM tannins and negligible quantities of low MM tannins interacted with CWM. Our results confirmed that more ripen berries may release higher amounts of anthocyanins and allowed us to hypothesize that CWM may play a role in the decrease of astringency which is associated with the progression of ripening.


Publication date: June 23, 2022

Issue: IVAS 2022

Type: Article


Allegro Gianluca1, Bautista-Ortín Ana-Belén2, Gómez-Plaza Encarna2, Pastore Chiara1,  Valentini Gabriele1, Mazzoleni Riccardo1 and Filippetti Ilaria1

1Department of Agricultural and Food Sciences – University of Bologna, Viale Fanin 46, 40127, Bologna, Italy
2Departamento de Tecnología de Alimentos, Nutrición y Bromatología – Universidad de Murcia (Spain)

Contact the author


anthocyanins, astringency, ripening, tannins, Vitis vinifera


IVAS 2022 | IVES Conference Series


Related articles…

Physiological and growth reaction of Shiraz/101-14 Mgt to row orientation and soil water status

Advanced knowledge on grapevine row orientation is required to improve establishment, management and outcomes of vineyards on terroirs with different environmental conditions (climate, soil, topography) and in view of a future change to more extreme climatic conditions. The purpose of this study was to determine the combined effect of row orientation, plant water status and ripeness level on the physiological and viticultural reaction of Shiraz/101-14 Mgt.

Effects of mechanical leafing and deficit irrigation on Cabernet Sauvignon grown in warm climate of California

San Joaquin Valley accounts for 40% of wine grape acreage and produces 70% of wine grape in California. Fruit quality is one of most important factors which impact the economical sustainability of farming wine grapes in this region. Due to the recent drought and expected labor cost increase, the wine industry is thrilled to understand how to improve fruit quality while maintaining the yield with less water and labor input. The present study aims to study the interactive effects of mechanical leafing and deficit irrigation on yield and berry compositions of Cabernet Sauvignon grown in warm climate of California.

The effects of cane girdling on berry texture properties and the concentration of some aroma compounds in three table grape cultivars

The marketability of the table grapes is highly influenced by the consumer demand; therefore the market value of the table grapes is mainly characterized by its berry size, colour, taste and texture. Girdling could cause accumulation of several components in plants above the ringing of the phloem including clusters and resulting improved maturity. The aim of the experiments was to examine the effect of girdling on berry texture characteristics and aroma concentration.

Application of a fluorescence-based method to evaluate the ripening process and quality of Pinot Blanc grape

The chemical composition of grape berries at harvest is one of the most important factors that should be considered to produce high quality wines. Among the different chemical classes which characterize the grape juice, the polyphenolic compound, such as flavonoids, contribute to the final taste and color of wines. Recently, an innovative non-destructive method, based on chlorophyll fluorescence, was developed to estimate the phenolic maturity of red grape varieties through the evaluation of anthocyanins accumulated in the berry skin. To date, only few data are available about the application of this method on white grape varieties.

Different yield regulation strategies in semi-minimal-pruned hedge (SMPH) and impact on bunch architecture

Yields in the novel viticulture training system Semi-Minimal-Pruned Hedge (SMPH) are generally higher compared to the traditional Vertical Shoot Positioning (VSP). Excessive yields have a negative impact on the vine and wine quality, which can result in substantial losses in yield in subsequent vintages (alternate bearing) or penalties in fruit quality. Therefore yield regulation is essential. The bunch architecture in SMPH differs from VSP. Generally there is a higher amount but smaller bunches with lower single berry weights in SMPH compared to VSP.