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…

Identification, quantification and organoleptic impact of « dried fruit » molecular markers in Merlot and Cabernet Sauvignon grapes and in red wines

The aromas found in young Bordeaux red wines made with Merlot and Cabernet Sauvignon suggest a complex mixture of aromas of fresh red fruits such as cherry or blackberry for Merlot, and strawberry or blackcurrant for Cabernet Sauvignon. The aromas of these wines are closely linked with the maturity of the grapes. The climate change that has occurred during the last decade in Bordeaux has induced changes in the ripening conditions of grape berries. It is now widely admitted that over-ripening of the berries during hot and dry summers results in the development of characteristic flavors reminiscent of cooked fruits (fig, prune). The presence of these overriding odors found in both musts and young wines affects the quality and subtlety of the wine flavor and may shorten its shelf life.

Effect of non-Saccharomyces yeast and lactic acid bacteria on selected sensory attributes and polyphenols of Syrah wines

Consumers predominantly use visual, aromatic and texture cues as quality/preference indicators to describe olfactory sensations. In this study, the effect of micro-organism in wine production was investigated using analytical and sensory techniques to achieve relevant analytical characterisation. Selected anthocyanins, flavan-3-ols, flavonols and phenolic acids were quantified in Syrah wines using RP-HPLC-DAD. Standard oenological parameters were also measured. Syrah grape must was fermented with various combinations of Saccharomyces cerevisiae (S. cerevisiae) and non-Saccharomyces (Metschnikowia pulcherrima or Hanseniaspora uvarum) yeasts, which was followed by sequential inoculation of lactic acid bacteria (LAB) (Oenococcus oeni or Lactobacillus plantarum).

DNA and type of grain: which factor does better explain sensory differences of sessile and pedunculate oaks?

Sessile oak and pedunculate oak have shown several differences of interest for enological purposes. Tannic and aromatic composition among sessile oak or pedonculate oak has been well studied. Sessile oak is generally more aromatic than pedunculated, while the later is more tannic. This scientific point of view is rarely applied to classify oak in cooperages. Most coopers use the type of grain to distinguish wide and thin grain.

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.

Evaluating South African Chenin blanc wine styles using an LC-MS screening method

Sorting Chenin blanc is one of the most important white wine cultivars in South Africa. It has received a lot of attention and accolades in the past years and more research than ever is dedicated to this versatile cultivar. 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). They are traditionally established with the aid of expert sensory evaluation, but the cost and the (subjective) human factor are aspects to be taken into account. A more objective and possibly robust way of assessing and attributing these styles can be the use of chemical analysis.