Search Results (11)

Accurately evaluating and quantifying microbial spoilage on wine grapes is a major challenge, especially in machine-harvested fruit that is no longer intact as a cluster when it arrives at the winery and cannot be visually inspected. The goal of the study was, using an infrared spectroscopy-based analytical system, to establish a unitless quantitative number that would reflect complex microbial spoilage and could be applied for all types of grapes with only one calibration model. Grapes (cultivars Riesling, Chenin Blanc, Chardonnay, Zinfandel and Petite Sirah) were hand-harvested in two consecutive vintages and separated in the vineyard into visually healthy clusters and infected grapes. Grapes were blended with increasing infection levels between 0 and 20% and models were created using known spoilage indicators. The resulting formula can be used to calculate a weighted index that reflects the microbial infection status of the grape material. Using a common spectroscopy instrument that is already present in larger wineries, the Grape Health Index allows for a quantitative quality assessment within two minutes at the test stand before the grape material is accepted. When visual inspection is not an option, this can help to make data-based quality and blending decisions at a very early stage. Full article

Seeds of different Vitis cultivars (V. vinifera subsp. vinifera) have an interesting diversity of shapes, ranging from the small seeds of high solidity and low aspect ratio in some species of Vitis and V. vinifera subsp. Sylvestris to other morphological types with elongated stalks, characteristic of the more recent cultivars, suggesting a transition with alterations in seed shape associated with groups of cultivars. J-index analysis is a morphometrical technique that measures the percentage similarity of seed images with geometric models. Three models based on the outlines of reference cultivars (a model based on the Spanish female cultivar Hebén; and mixed models for French and German Chenin and Gewürtztraminer, both related to Savagnin Blanc; and Regina dei Vigneti and Muscat Hamburg, related with the Muscat group) have been applied to select the average outlines (Aos) resembling these models from a collection of cultivars maintained at IMIDRA. Three groups resulted, called Hebén, Chenin, and Regina, with 15, 25, and 18 cultivars, respectively. Principal component analysis (PCA) with the Fourier coefficients of the Aos for these cultivars and seeds of other species of Vitis and V. vinifera subsp. sylvestris showed differences between groups. Specific Fourier coefficients were related with geometric properties of the seeds, circularity, roundness, aspect ratio, and solidity as well as with diverse measurements of curvature allowing to establish hypothesis about the change in geometric properties along the evolution of cultivars. Full article

Online text is a source of data in many fields, but it is yet to be explored by sensory scientists. The present work aimed to explore the suitability of using a bibliometric methodology such as Latent Semantic Analysis (LSA) to understand and define wine sensory spaces. Data were also explored by the more conventional Multiple Correspondence Analysis (MCA). The present work shows the potential use of LSA in sensory science; the first part of the study investigates the sensory profile of Swedish Solaris wines, while the second part focuses on understanding their fit with two international monovarietal white wines (Albariño and Chenin Blanc). The results show that the majority of Swedish Solaris wines could be associated with two different styles (LSA topics). However, there is no evidence of a cultivar typicality, as when comparing the Solaris wines with Albariño and Chenin Blanc, they shared features with both cultivars. Chenin Blanc was also found to be associated with different styles. In contrast, Albariño wines showed to have more unique features as the majority were associated with a single LSA topic. Full article

Low-temperature treatments preceding alcoholic fermentation are becoming increasingly popular and have been used in winemaking as a tool to improve wine colour, aroma, and quality. Additionally, the pre-fermentative treatment of grapes with cryogenic agents protects the grape juice (must) from oxidation by reducing the diffusion of atmospheric oxygen into the liquid phase during the winemaking process. Resultant wines were reported to have enhanced varietal aromas, increased complexity, and higher thiol levels. Indications are that increased contact time between skin and juice improves the extraction of the compounds and/or precursors. Recently, there has been considerable interest in the production of wines with enhanced varietal aromas and improved quality by applying innovative winemaking technologies. This review aims to provide an overview of the aroma and organoleptic quality of Sauvignon blanc and Chenin blanc wines produced from grapes that were subjected to pre-fermentative cryogenic treatments including the impact aroma compounds, i.e., volatile thiols and methoxypyrazines. Full article

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 MFA models were more representative than PCA, as indicated by high RV coefficients between MFA and each individual block. Therefore, MFA approaches were better suited for multi-modal data than PCA. This work approached data fusion systematically and showed the type of decisions that must be made and how to evaluate their consequences. Proper integration of data sets, instead of concatenation, is an important aspect to consider in multi-modal data fusion. Full article

Grapes exposed to smoke can result in wines that have unacceptable high levels of volatile phenols. High volatile phenols levels have a negative impact on wine quality. This study aimed to determine the levels of volatile phenols in wines produced from smoke-exposed juice by a selection of commercial wine yeasts and to determine if yeast selection affected the perception of smokiness in wine. Commercial white and red wine yeasts were screened for the production of volatile phenols in smoke-exposed Chenin Blanc and Merlot juice. Volatile phenol levels were determined by GC-MS/MS and wines were also subjected to sensory evaluation. Volatile phenol levels in smoked wines varied and was affected by yeast strain. The highest guaiacol levels in Chenin Blanc were found in wines fermented with QA23, while Merlot wines that underwent spontaneous alcoholic fermentation contained the highest levels. The levels of volatile phenols differed significantly between the smoked and unsmoked wines, and the sensory results supported the chemical data. Volatile phenols had a negative effect on Chenin Blanc flavor profiles even when the levels were below odor detection thresholds. Yeast selection is important and can affect the volatile phenol levels and flavor profiles of wines. Full article

Culture is an important factor that influences how marketing interacts with food choice. This study aims at exploring the effect of consumers’ Country of Origin (COO) on wine representations and perception using Chenin blanc as a model. The first objective was to evaluate the role of origin in the construction of the representation. We used the theoretical framework of social representation to compare South African (SA) and French consumers’ representations via a word association task. The results indicated that SA representations are dominated by consumers’ experience of the wine (sensory and emotional dimensions), whereas French representations are dominated by the wine itself, in particular its origin and mode of consumption. The second objective was to evaluate the effect of origin on wine categorization in two conditions: with and without information concerning the two geographical origins of the samples. Results showed that providing information on the origin of the wines affected French participants more than SA participants. In both conditions, the groups of wines formed in the sorting tasks by SA participants were based on sensory descriptors and appeared not to be impacted by the information on origin. In contrast, providing information on the origin of the wines to French participants led to an increased use of the words “Loire”, “South Africa” and “familiar” suggesting a different sorting strategy more deliberately based on the origin of the wines. Our findings have important implications for the marketing and export activities within the wine industry. Full article

The sensorial evaluation of Chenin blanc wine produced with different types of oak wood treatments over time has not been investigated before. The main aim of this study was to assess the sensory profile, using a trained panel, of a South African Chenin blanc wine fermented and matured in old barrels, three types of new oak barrels, two types of oak staves as well as a stainless steel tank over time, which has not been done before. Results indicate mainly separation between the stainless-steel tank/old barrel treatments from the stave and new barrel treatments, with separation between the latter two treatments also being found. More fruity descriptors were used in the stainless-steel tank and old barrel treatments, with oak-related descriptors being used in the stave and new barrel treatments. Separation between among the new barrel and stave treatments were also noted, which was still reflected during bottle maturation. These results indicate that winemakers need to take cognizance of the sensorial differences induced by barrel and stave maturation in white wines and how these evolve over time. Full article

The aim of the study was to propose a methodology for the elucidation of sensory and chemical wine quality drivers. The winners of the 2018 Top 10 Chenin Blanc and Top 10 Pinotage challenges and additional lower scoring wines for each cultivar were evaluated. The two sets underwent sensory profiling by Check-All-That-Apply (CATA) and a 20-point quality rating by industry experts in non-competition conditions and chemical fingerprinting by Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS). Data were submitted to Correspondence Analysis (CA) and Principal Component Analysis (PCA) for sensory and chemistry, respectively, from which the standardised deviates were correlated to quality scores to identify the quality drivers. The results illustrated the possibility to determine positive and negative sensory quality drivers (attributes), while the identification of drivers for chemistry (ions) was challenging due to the number of signals generated by the fingerprinting technique. The configurations of the sensory and chemical spaces were compared, but the similarities were relatively low as measured by Regression Vector (RV) coefficients, 0.437 and 0.505 for Pinotage and Chenin Blanc, respectively. The proposed methodology can also be used to explore the sensory space of wine sample sets with the added dimension of the quality drivers which, in turn, highlight the experts’ opinions on what makes a winning wine. Full article

São Francisco Valley (SFV) is located in Northeastern Brazil, in a tropical semi-arid region where one vine can produce two harvests per year, due to high temperatures, solar radiation rates, and irrigation throughout the year. This is the main characteristic differing this from other winegrowing region in the world. The objective of this study was to characterize volatile profiles of sparkling wines produced by the traditional method, using Chenin Blanc and Syrah grapes, the two main varieties used for white and red wines, respectively, grown in the region. The sparkling wines remained on lees for six months maturing. The sparkling wines were characterized by the parameters density, pH, total titratable and volatile acidities, residual sugars, dry extract, alcohol content, total phenolic compounds, in vitro antioxidant activity and volatile fraction. The volatile fraction extraction was performed by the HS-SPME technique and tentative identification of the volatile compounds was carried out with GC-MS using the scan mode. A total of 33 volatile compounds were identified, among them 11 alcohols, 13 esters, five carboxylic acids, and four different chemical classes. The volatile profile of Chenin Blanc sparkling wine was associated mainly to 2,3-butanediol, 3-ethoxypropan-1-ol, diethyl succinate, and ethyl decanoate, while Syrah sparkling wine was characterized by benzaldehyde, butyric acid, and some acetates. This study reported for the first time volatile profiles of traditional sparkling wines from SFV, as new products, contributing to better understand the quality potential of these beverages for a tropical semi-arid region. Full article

Two novel applications using a portable and wireless sensor system (e-nose) for the wine producing industry—The recognition and classification of musts coming from different grape ripening times and from different grape varieties—Are reported in this paper. These applications are very interesting because a lot of varieties of grapes produce musts with low and similar aromatic intensities so they are very difficult to distinguish using a sensory panel. Therefore the system could be used to monitor the ripening evolution of the different types of grapes and to assess some useful characteristics, such as the identification of the grape variety origin and to prediction of the wine quality. Ripening grade of collected samples have been also evaluated by classical analytical techniques, measuring physicochemical parameters, such as, pH, Brix, Total Acidity (TA) and Probable Grade Alcoholic (PGA). The measurements were carried out for two different harvests, using different red (Barbera, Petit Verdot, Tempranillo, and Touriga) and white (Malvar, Malvasía, Chenin Blanc, and Sauvignon Blanc) grape musts coming from the experimental cellar of the IMIDRA at Madrid. Principal Component Analysis (PCA) and Probabilistic Neural Networks (PNN) have been used to analyse the obtained data by e-nose. In addition, and the Canonical Correlation Analysis (CCA) method has been carried out to correlate the results obtained by both technologies. Full article