Jun Niimi

Effects of Immersive Context and Wine Flavor on Consumer Wine Flavor Perception and Elicited Emotions

Food studies have shown that emotional responses can be influenced by food alone and by its environmental context. The influence of context on perception and liking of red wine flavors and on the emotions evoked is poorly understood. The primary aim of this research was to examine the effect of wine flavors and context by immersive environment on consumer-perceived intensities of green and floral flavors, liking, and emotions elicited during wine consumption. Red wine consumers (n = 105) tasted three Cabernet Sauvignon wines: an unaltered control wine (CW), green wine (GW; control wine spiked with 3-isobutyl-2-methoxypyrazine), and floral wine (FW; control wine spiked with rose water), in both a “floral” room (FR) and a “green” room (GR). The wine consumers were asked to taste and rate the intensity of green and floral flavors, hedonic liking, and the emotions elicited. The results showed that in both rooms, FW was rated consistently higher in floral flavor and GW was rated higher in green flavor. CW and FW were significantly (p < 0.001) more liked than the GW. Based on wine liking, three clusters were identified. CW and FW evoked significantly higher positive emotions than GW (p < 0.05), while GW evoked significantly higher negative emotions than CW and FW (p < 0.05) in both rooms. The effect of immersive environment did not influence flavor perception, hedonic liking, or emotional responses. Consumers were also separated into three clusters according to their liking of wines tasted, and despite clusters having identical liking for certain wines, the associated emotions differed.

Linking Sensory Properties and Chemical Composition of Vitis vinifera cv. Cabernet Sauvignon Grape Berries to Wine

It is conventional wine industry practice for winemakers and grapegrowers to taste winegrapes to determine their fitness for producing various wine styles of different quality. However, the ability to predict wine style from tasting grapes is unverified, and the relationship among the sensory characters of grapes and wine is poorly understood. The objective of the study was to investigate the sensory properties of Cabernet Sauvignon grapes and the corresponding wines, and to determine the relationships between the two data sets. Grapes were harvested between 23 and 25 Brix from eight locations across the state of South Australia over two vintages and vinified using a standardized protocol. A total of 25 samples from across the eight locations were harvested for each vintage. The grapes and wines were evaluated by a sensory panel trained in descriptive analysis. Grapes were evaluated using the berry sensory assessment (BSA) methodology previously described in the literature, and the basic chemical parameters of the grapes and wines were measured. Samples were consistently discriminated by their chemical and sensory properties within the grape and by wine data sets across the vintages. Five sensory attributes of wine were consistently modeled with moderate to high regressions using BSA attributes and berry-chemical measures. Finding berry sensory attributes that consistently relate to wine style and profile remains challenging. The basic chemical measures, including Brix, anthocyanins, and chroma of grape homogenates, were reliable contributors to wine sensory attributes for both vintages.

Sensory profiling and quality assessment of research Cabernet Sauvignon and Chardonnay wines; quality discrimination depends on greater differences in multiple modalities

The sensory profiles of Cabernet Sauvignon and Chardonnay research wines were determined and analysed together with wine quality scores of expert judges. Research Cabernet Sauvignon and Chardonnay wines from three and two vintages, respectively, were evaluated. Wines of both varieties were produced with grapes harvested from across South Australian wine making regions throughout 2013-2016 vintages. Wines within varieties were vinified identically across samples and also across vintages. Wines were profiled in triplicate using descriptive analysis with a panel of trained assessors (n=9-11) and graded for quality in triplicate by winemakers (n=6-9) using a sorting task based on similarity of quality and with the aid of definitions formed by the winemakers prior to sorting. The data sets were analysed using canonical variate analysis (CVA) and multidimensional scaling (MDS). The scores from CVA and MDS per variety per vintage were analysed using Generalised Procrustes Analysis (GPA). Differences in Cabernet Sauvignon samples by provenance were determined, where associations with regions by sensory attributes were observed in all vintages. These wines were consistently sorted based on quality by the winemakers, evident from GPA. Chardonnay in comparison were poorly discriminated in both sensory profiles and quality. The combination of descriptive sensory analysis with sorting was complimentary to each other and was able to uncover additional information about the sensory properties of wines when the two methods were used in concert, such as balance and complexity. However the red wine variety had more intrinsic characteristics that lead to better discrimination based on sensory properties and hence quality than the white wine variety.

Application of sequential and orthogonalised-partial least squares (SO-PLS) regression to predict sensory properties of Cabernet Sauvignon wines from grape chemical composition

The current study determined the applicability of sequential and orthogonalised-partial least squares (SO-PLS) regression to relate Cabernet Sauvignon grape chemical composition to the sensory perception of the corresponding wines. Grape samples (n = 25) were harvested at a similar maturity and vinified identically in 2013. Twelve measures using various (bio)chemical methods were made on grapes. Wines were evaluated using descriptive analysis with a trained panel (n = 10) for sensory profiling. Data was analysed globally using SO-PLS for the entire sensory profiles (SO-PLS2), as well as for single sensory attributes (SO-PLS1). SO-PLS1 models were superior in validated explained variances than SO-PLS2. SO-PLS provided a structured approach in the selection of predictor chemical data sets that best contributed to the correlation of important sensory attributes. This new approach presents great potential for application in other explorative metabolomics studies of food and beverages to address factors such as quality and regional influences.

Linking the Sensory Properties of Chardonnay Grape Vitis vinifera cv. Berries to Wine Characteristics

Formal or informal sensory analyses of grapes are often used to determine when a parcel of fruit should be harvested to produce a certain wine style. This study investigated whether relationships exist between sensory perceptions and basic chemical measures of Chardonnay grape berries and the corresponding wines. Chardonnay grape parcels were harvested at commercial maturity from across South Australia in vintages 2015 and 2016, yielding a total of 25 and 24 samples, respectively. Grapes were evaluated using berry sensory assessment (BSA) and vinified identically using small-scale winemaking, and the resulting wines were evaluated with descriptive sensory analysis. Sensory assessors were trained in the respective sensory evaluation methods. Chardonnay grape and wine samples were discriminated by the panel according to sensory attributes, and the fruit could also be discriminated by basic chemistry measures. However, differences in Chardonnay wines were subtle compared with those in grapes, as indicated by low effect sizes. Moderate validation models (R2Val = 0.53 to 0.81) of partial least squares regression (PLSR) 1 were determined in the 2015 vintage, using BSA attributes as x-variables and wine sensory attributes as y-variables, but poor models were obtained with the 2016 vintage (R2Val < 0.5). In the 2015 models, relationships were found for wine attributes of heat, sourness, and astringency, possibly due to slight variations in ripeness. Strong relationships that revealed wine style from variations in grapes were not found. Overall, relating the sensory characteristics of Chardonnay grapes to the wines was challenging and indicated that variation in style of these varietal wines does not greatly depend on the raw grape material.

Reduction of Red Wine Astringency Perception Using Vegetable Protein Fining Agents

The use of vegetable proteins to fine astringent compounds in wine has gained increased interest due to the pressure of consumer demand. The objective of this study was to compare the ability of alternative vegetable proteins (derived from rice, soy, pea, or potato) to reduce tannin and thereby astringency, relative to that of traditional fining agents (gelatin and polyvinylpolypyrrolidone [PVPP]) in a commercial wine with added grape seed extract. Total tannin and phenolics, SO2-resistant pigments, pH, and color of the treated wines were determined, and astringency intensity perception was evaluated by a trained sensory panel (n = 9). Potato, pea, soy, and gelatin proteins similarly reduced total tannin concentration. Similar to PVPP, addition of rice or soy protein reduced total phenolics. These alternative vegetable proteins also influenced the chroma, which may change the depth of wine color. Furthermore, this study was the first to evaluate the change in astringency sensation resulting from the use of rice and soy proteins as alternative fining agents. The type of vegetable proteins used appeared to fine different types of polyphenolic compounds, an observation that was reflected on astringency perception and requires further investigation. The chemical and sensory measures showed that rice and potato proteins have the potential to replace PVPP and gelatin, respectively.