Macrowine 2021
IVES 9 IVES Conference Series 9 Evaluation of Polarized Projective Mapping as a possible tool for attributing South African Chenin blanc dry wine styles

Evaluation of Polarized Projective Mapping as a possible tool for attributing South African Chenin blanc dry wine styles

Abstract

Multiple Factor Analysis (MFA) According to the Chenin blanc Association of South Africa, there are three recognized dry wine styles, Fresh and Fruity (FF), Rich and Ripe Unwooded (RRU), and Rich and Ripe Wooded (RRW), classically attributed with the help of sensory evaluation. One of the “rapid methods” has drawn our attention for the purpose of simplifying and making style attribution for large sample sets, evaluated during different sessions, more robust. Polarized Projective Mapping (PPM) is a hybrid of Projective Mapping (PM) and Polarised Sensory Positioning (PSP). It is a reference-based method in which poles (references) are used for the evaluation of similarities and dissimilarities between samples. Panelists are presented with “free-moving” products to arrange around the poles, according to similarities and dissimilarities, to create a 2D product map. Additionally, the judges give a description of the samples, generating a short list of attributes. Our approach to testing this method was to first establish the poles using PM, then test the model using PPM with samples that were either known (used in the PM session and that contributed to the choice of poles) or unknown. The sample set consisted of 18 commercial Chenin blanc wines, vintages 2013 and 2014, from the three representative styles, chosen according to the tasting notes description. Four PPM experiments were performed. The poles were kept constant among the PPM experiments, while different combinations of “free-moving” wines were evaluated to test the consistency of product groupings. In all tasks sensory descriptors were generated. For each session 15 judges were recruited. Each judge repeated the exercise after a 15 minute break. For PM the sample set consisted of 12 samples (9 wines, 3 of them duplicates). For PPM, the sample sets also had 12 samples, with one of the poles and one other sample duplicated. The PPM sessions were organized as follows: PPM1 same samples as PM, PPM2 and PPM3 half known and half unknown samples, and PPM4 only unknown samples. The data generated was evaluated statistically by means of multiple factor analysis (MFA). Multiple factor analysis (MFA) on the individual tasks showed in the PM and all four PPM tasks, the RRW group separated most clearly from other wines and blind duplicates of this style grouped well together. The FF and RRU styles grouped less consistently from one task to another and blind duplicates were not grouped as closely to one another. MFA results comparing all four PPM experiments showed good repeatability in grouping of wines among the separate sessions, especially for wooded wines. New rapid methods provide significant cost benefits for the wine industry and researchers. PPM may be a useful tool for researchers to apply in the analysis of large sample sets of wines.

Publication date: May 17, 2024

Issue: Macrowine 2016

Type: Poster

Authors

Astrid Buica*, Christine Wilson, Jeanne Brand

*Stellenbosch University

Contact the author

Tags

IVES Conference Series | Macrowine | Macrowine 2016

Citation

Related articles…

Correlations between N,S,O-heterocycle levels and age of Champagne base wines

Champagne regulation allows winegrowers to stock small amounts of still wines in order to compensate vintages’ quality shifts mainly due to climate variations. According to their technical requirements and house style some Champagne producers (commonly named “Champagne houses”) use these stored wines in the blend in order to introduce an element of complexity. These wines possess the particularity of being aged on fine lees in thermo-regulated stainless steel tanks. The Champagne house of Veuve Clicquot Ponsardin has several wines stored this way.

Microbial life in the grapevine: what can we expect from the leaf microbiome?

The above-ground parts of plants, which constitute the phyllosphere, have long been considered devoid of bacteria and fungi, at least in their internal tissues and microbial presence there was long considered a sign of disease. However, recent studies have shown that plants harbour complex bacterial communities, the so-called “microbiome”[1]. We are only beginning to unravel the origin of these bacterial plant inhabitants, their community structure and their roles, which in analogy to the gut microbiome, are likely to be of essential nature. Among their multifaceted metabolic possibilities, bacteria have been recently demonstrated to emit a wide range of volatile organic compounds (VOCs), which can greatly impact the growth and development of both the plant and its disease-causing agents.

Characterization of various groups of pyranoanthocyanins in Merlot red wine

In red wines, anthocyanins evolve during the wine-making process and ageing. They react with other compounds (such as vinylphenols, acetaldehyde, pyruvic acid…) to form a stable family of compounds called pyranoanthocyanins. Furthermore, the oxidation process can modify the anthocyanic profile of a red wine. It is also interesting to evaluate the occurrence of the different subclasses of pyranoanthocyanins and to characterize their chemical properties. The first objective of this study is to evaluate the occurrence of the different groups of pyranoanthocyanins in an oxidised Merlot wine by a centrifugal partition chromatography strategy. The second goal is to evaluate their relative impact in red wines from Bordeaux region by measuring their concentrations.

Comparison of fortified, sfursat and passito winemaking techniques for the enhancement of the oenological potential of the black grape cultivar Moscato nero d’Acqui (Vitis vinifera L.)

One of the key factors of the economical development of viticulture and wine industry in specific limited areas is the exploitation of ancient, local grape varieties. Therefore, in recent years the growing interest to rediscover minor varieties, previously cultivated, has promoted many studies. With this regard, the focus of this study was the Vitis vinifera L. cultivar Moscato nero d’Acqui, nowadays found only in old vineyards in the Acqui zone (North-West Italy). In particular, the aims of this work were: i) to investigate secondary metabolites profile of the grapes, and ii) to evaluate the attitude to the production of special wines.

Oenological features of Sangiovese wine from vinification of whole grape berries

The present study was performed in a traditional winery located in the viticultural area of Brunello di Montalcino, Siena, Italy, in the vintage 2015. Actually, in this winery Sangiovese grape musts are fermented in large oak barrels by a single strain of Saccharomyces cerevisiae previously isolated in the same winery. Pumping over operations are carried out once or twice a day until the end of alcoholic fermentations. The aim of this work was to investigate on the oenological properties of Sangiovese wine produced with the traditional winemaking process adopted by the winery under study obtained from the fermentation of whole berries compared to that from crushed grape must. In particular, two lots of 65q of Sangiovese grapes from the same 3ha vineyard were vinified in 150hL oak barrels.