Jeanne Brand - Academia.edu (original) (raw)
Papers by Jeanne Brand
European Food Research and Technology
Beverages
In oenology, statistical analyses are used for descriptive purposes, mostly with separate sensory... more In oenology, statistical analyses are used for descriptive purposes, mostly with separate sensory and chemistry data sets. Cases that combine them are mostly supervised, usually seeking to optimize discrimination, classification, or prediction power. Unsupervised methods are used as preliminary steps to achieving success in supervised models. However, there is potential for unsupervised methods to combine different data sets into comprehensive, information-rich models. This study detailed stepwise strategies for creating data fusion models using unsupervised techniques at different levels. Principal component analysis (PCA) and multiple factor analysis (MFA) were used to combine five data blocks (four chemistry and one sensory). The model efficiency and configurational similarity were evaluated using eigenvalues and regression vector (RV) coefficients, respectively. The MFA models were less efficient than PCA, having gradual distributions of eigenvalues across model dimensions. The ...
OENO One
The levels of varietal thiols and the role these compounds play in Colombard wine have not been i... more The levels of varietal thiols and the role these compounds play in Colombard wine have not been investigated in detail. This study assessed the levels of the varietal thiols 4-methyl-4-sulfanylpentan-2-one (4MSP), 3-sulfanylhexyl acetate (3SHA) and 3-sulfanylhexan-1-ol (3SH) and their sensory effects in 24 young South African Colombard wines. Levels of 3SHA and 3SH were, in general, in line with those previously reported in South African Chenin blanc and Sauvignon blanc wines. Levels of 4MSP were, in general, found at a narrower range than those reported for Sauvignon blanc wines. Twelve of these wines were also sensorially analysed by a panel of wine industry experts. Aroma descriptors, such as guava, passion fruit, sweat and tomato leaf, which have previously been linked to 3SH and 3SHA, were also found, especially in the wines containing higher levels of these two compounds. Good correlations between 3SHA and sweat and guava were found. This study contributes to the knowledge of ...
OENO One
Patterns in data obtained from wine chemical and sensory evaluations are difficult to decipher us... more Patterns in data obtained from wine chemical and sensory evaluations are difficult to decipher using classical statistics. Coupling data fusion with machine learning techniques could assist in solving these issues and lead to new hypotheses. The current study investigated the applicability of classical and machine learning pattern recognition approaches for oenological applications. A sample set of 23 Chenin blanc wines made from young (< 35 years) and old (> 35 years) vines were analysed (recently bottled (Year 1) and after two years of storage (Year 2)). Sensory (sorting) and chemical (NMR: nuclear magnetic resonance and HRMS: high-resolution mass spectrometry) data were collected. Multiple factor analysis (MFA) was used for the data fusion. Cluster analysis was performed by agglomerative hierarchical clustering (AHC) and fuzzy k-means. Optimal cluster conditions were found for both methods and the cophenetic coefficient was used to assess the confidence of fit. Given the la...
OENO One
Wine is characterised by an underlying aromatic volatile profile, which allows human subjects to ... more Wine is characterised by an underlying aromatic volatile profile, which allows human subjects to easily recognise the product as “wine” by smell alone. Yeast metabolism significantly contributes to wine organoleptic properties, and some yeast metabolism-derived compounds contribute to the vinous character of wine. However, the relative contribution of yeast and grape-derived metabolic compounds to the sensory perception of a product as “wine-like” remains unexamined. This study explores the possibility of creating a wine-like aroma by yeast metabolic activity alone. For this purpose, we fermented a simple synthetic media without any grape-derived aromatic compounds or precursors thereof. Fermentation products were evaluated for the degree of wine-like sensory perception. The synthetic grape juice nitrogen, sterol and fatty acid composition were altered to improve the recognition of this character. Initial fermentations resulted in products that were not recognised as wine-like, but ...
Critical Reviews in Food Science and Nutrition
The original publication is available at http://www.vitismagazine.cl/index.htmFood ScienceINTRODU... more The original publication is available at http://www.vitismagazine.cl/index.htmFood ScienceINTRODUCTION: The color of the berry is a new and important indicator to determine the optimum ripeness of the fruit for the different styles of white wine, because the hues can help predict the aromatic profiles of wines. ONe Of The MOST important and difficult tasks for a vintner and a winemaker is to predict the style of wine that can be obtained according to the characteristics of the grapes and winemaking process. Traditional indicators such as brix, tartaric and malic acids, titratable acidity, tannins, anthocyanins, and so on, are strongly associated with the taste of wine. but that’s not enough. being able to predict the style of wine based on the aroma would certainly prove useful. This is one of the reasons why the optimum ripeness of the fruit is still relevant within the scientific community and the wine industryINTRODUCCION: Una de las tareas más importantes y difíciles de un vitic...
South African Journal of Enology and Viticulture, 2020
Although South African vineyards are still young by European standards, there is a belief in the ... more Although South African vineyards are still young by European standards, there is a belief in the industry that vines aged 35 or more years produce grapes and wines with specific characteristics ("old vine wines"). The aim of this study was to investigate the existence of the concept of old vine Chenin blanc wines using a typicality rating and sorting tasks. Chenin blanc wines were made from grapes harvested from vines aged five to 45 years old. Winemaking was standardised, with no wood contact. Typicality rating and sorting tasks were performed on young (first-stage) and two-year bottle-aged (second-stage) wines. Principal component analysis (PCA) on rating data demonstrated judge consensus, but no correlation was found between vine age and typicality rating. Sorting results were submitted to agglomerative hierarchical clustering (AHC) performed on the correspondence analysis (CA) and multidimensional scaling (MDS) results for grouping and attributes resulting from the sorting task. The clusters were different for the young wines and two-year bottle-aged wines. The verbal aspect of the sorting demonstrated the judges' agreement on the concept of old vine Chenin blanc, shown by the annotation of the old vine group as 'complex', 'balance', 'rich' and 'good mouthfeel'. However, because the judges did not sort the wines according to vine age, the perceptual aspect of the concept could not be confirmed, its features could not be tested further, and the sensory space could not be built. Abbreviations: RV (regression vector); PCA (principal component analysis); MDS (multidimensional scaling); CA (correspondence analysis); AHC (agglomerative hierarchical clustering); DA (descriptive analysis); CATA (check all that apply)
South African Journal of Enology and Viticulture, 2018
Interaction studies are some of the most interesting sensory experiments that highlight the effec... more Interaction studies are some of the most interesting sensory experiments that highlight the effect of composition on wine perception. The use of single compounds, viz. an ester (ethyl hexanoate), a terpene (linalool) and a thiol (3-mercaptohexanol, 3MH), which have previously been shown to be representative of Chenin blanc wines, resulted in typical descriptors for these compounds, such as 'apple, 'floral' and 'guava' respectively. Interaction effects were observed between the compounds, and these were reflected in both the nature and the level of attributes generated. Additionally, interaction effects between the compounds (singles and combinations) and the wine matrix indicated that the latter plays an important role in the perception of wine aromas. The use of a dearomatised neutral wine base added an extra dimension to this study, which usually is done in a simpler matrix, such as a model wine.
European Food Research and Technology
Beverages
In oenology, statistical analyses are used for descriptive purposes, mostly with separate sensory... more In oenology, statistical analyses are used for descriptive purposes, mostly with separate sensory and chemistry data sets. Cases that combine them are mostly supervised, usually seeking to optimize discrimination, classification, or prediction power. Unsupervised methods are used as preliminary steps to achieving success in supervised models. However, there is potential for unsupervised methods to combine different data sets into comprehensive, information-rich models. This study detailed stepwise strategies for creating data fusion models using unsupervised techniques at different levels. Principal component analysis (PCA) and multiple factor analysis (MFA) were used to combine five data blocks (four chemistry and one sensory). The model efficiency and configurational similarity were evaluated using eigenvalues and regression vector (RV) coefficients, respectively. The MFA models were less efficient than PCA, having gradual distributions of eigenvalues across model dimensions. The ...
OENO One
The levels of varietal thiols and the role these compounds play in Colombard wine have not been i... more The levels of varietal thiols and the role these compounds play in Colombard wine have not been investigated in detail. This study assessed the levels of the varietal thiols 4-methyl-4-sulfanylpentan-2-one (4MSP), 3-sulfanylhexyl acetate (3SHA) and 3-sulfanylhexan-1-ol (3SH) and their sensory effects in 24 young South African Colombard wines. Levels of 3SHA and 3SH were, in general, in line with those previously reported in South African Chenin blanc and Sauvignon blanc wines. Levels of 4MSP were, in general, found at a narrower range than those reported for Sauvignon blanc wines. Twelve of these wines were also sensorially analysed by a panel of wine industry experts. Aroma descriptors, such as guava, passion fruit, sweat and tomato leaf, which have previously been linked to 3SH and 3SHA, were also found, especially in the wines containing higher levels of these two compounds. Good correlations between 3SHA and sweat and guava were found. This study contributes to the knowledge of ...
OENO One
Patterns in data obtained from wine chemical and sensory evaluations are difficult to decipher us... more Patterns in data obtained from wine chemical and sensory evaluations are difficult to decipher using classical statistics. Coupling data fusion with machine learning techniques could assist in solving these issues and lead to new hypotheses. The current study investigated the applicability of classical and machine learning pattern recognition approaches for oenological applications. A sample set of 23 Chenin blanc wines made from young (< 35 years) and old (> 35 years) vines were analysed (recently bottled (Year 1) and after two years of storage (Year 2)). Sensory (sorting) and chemical (NMR: nuclear magnetic resonance and HRMS: high-resolution mass spectrometry) data were collected. Multiple factor analysis (MFA) was used for the data fusion. Cluster analysis was performed by agglomerative hierarchical clustering (AHC) and fuzzy k-means. Optimal cluster conditions were found for both methods and the cophenetic coefficient was used to assess the confidence of fit. Given the la...
OENO One
Wine is characterised by an underlying aromatic volatile profile, which allows human subjects to ... more Wine is characterised by an underlying aromatic volatile profile, which allows human subjects to easily recognise the product as “wine” by smell alone. Yeast metabolism significantly contributes to wine organoleptic properties, and some yeast metabolism-derived compounds contribute to the vinous character of wine. However, the relative contribution of yeast and grape-derived metabolic compounds to the sensory perception of a product as “wine-like” remains unexamined. This study explores the possibility of creating a wine-like aroma by yeast metabolic activity alone. For this purpose, we fermented a simple synthetic media without any grape-derived aromatic compounds or precursors thereof. Fermentation products were evaluated for the degree of wine-like sensory perception. The synthetic grape juice nitrogen, sterol and fatty acid composition were altered to improve the recognition of this character. Initial fermentations resulted in products that were not recognised as wine-like, but ...
Critical Reviews in Food Science and Nutrition
The original publication is available at http://www.vitismagazine.cl/index.htmFood ScienceINTRODU... more The original publication is available at http://www.vitismagazine.cl/index.htmFood ScienceINTRODUCTION: The color of the berry is a new and important indicator to determine the optimum ripeness of the fruit for the different styles of white wine, because the hues can help predict the aromatic profiles of wines. ONe Of The MOST important and difficult tasks for a vintner and a winemaker is to predict the style of wine that can be obtained according to the characteristics of the grapes and winemaking process. Traditional indicators such as brix, tartaric and malic acids, titratable acidity, tannins, anthocyanins, and so on, are strongly associated with the taste of wine. but that’s not enough. being able to predict the style of wine based on the aroma would certainly prove useful. This is one of the reasons why the optimum ripeness of the fruit is still relevant within the scientific community and the wine industryINTRODUCCION: Una de las tareas más importantes y difíciles de un vitic...
South African Journal of Enology and Viticulture, 2020
Although South African vineyards are still young by European standards, there is a belief in the ... more Although South African vineyards are still young by European standards, there is a belief in the industry that vines aged 35 or more years produce grapes and wines with specific characteristics ("old vine wines"). The aim of this study was to investigate the existence of the concept of old vine Chenin blanc wines using a typicality rating and sorting tasks. Chenin blanc wines were made from grapes harvested from vines aged five to 45 years old. Winemaking was standardised, with no wood contact. Typicality rating and sorting tasks were performed on young (first-stage) and two-year bottle-aged (second-stage) wines. Principal component analysis (PCA) on rating data demonstrated judge consensus, but no correlation was found between vine age and typicality rating. Sorting results were submitted to agglomerative hierarchical clustering (AHC) performed on the correspondence analysis (CA) and multidimensional scaling (MDS) results for grouping and attributes resulting from the sorting task. The clusters were different for the young wines and two-year bottle-aged wines. The verbal aspect of the sorting demonstrated the judges' agreement on the concept of old vine Chenin blanc, shown by the annotation of the old vine group as 'complex', 'balance', 'rich' and 'good mouthfeel'. However, because the judges did not sort the wines according to vine age, the perceptual aspect of the concept could not be confirmed, its features could not be tested further, and the sensory space could not be built. Abbreviations: RV (regression vector); PCA (principal component analysis); MDS (multidimensional scaling); CA (correspondence analysis); AHC (agglomerative hierarchical clustering); DA (descriptive analysis); CATA (check all that apply)
South African Journal of Enology and Viticulture, 2018
Interaction studies are some of the most interesting sensory experiments that highlight the effec... more Interaction studies are some of the most interesting sensory experiments that highlight the effect of composition on wine perception. The use of single compounds, viz. an ester (ethyl hexanoate), a terpene (linalool) and a thiol (3-mercaptohexanol, 3MH), which have previously been shown to be representative of Chenin blanc wines, resulted in typical descriptors for these compounds, such as 'apple, 'floral' and 'guava' respectively. Interaction effects were observed between the compounds, and these were reflected in both the nature and the level of attributes generated. Additionally, interaction effects between the compounds (singles and combinations) and the wine matrix indicated that the latter plays an important role in the perception of wine aromas. The use of a dearomatised neutral wine base added an extra dimension to this study, which usually is done in a simpler matrix, such as a model wine.