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| 2. |
- Kang, W., et al.
(författare)
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Chemical and sensory impacts of Accentuated Cut Edges (ACE) grape must polyphenol extraction technique on shiraz wines
- 2020
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Ingår i: Foods. - : MDPI AG. - 2304-8158. ; 9:8
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Tidskriftsartikel (refereegranskat)abstract
- Accentuated Cut Edges (ACE) is a recently developed grape must extraction technique, which mechanically breaks grape skins into small fragments but maintains seed integrity. This study was the first to elucidate the effect of ACE on Shiraz wine's basic chemical composition, colour, phenolic compounds, polysaccharides and sensory profiles. A further aim was to investigate any potential influence provided by ACE on the pre-fermentation water addition to must. ACE did not visually affect Shiraz wine colour, but significantly enhanced the concentration of tannin and total phenolics. Wine polysaccharide concentration was mainly increased in response to the maceration time rather than the ACE technique. ACE appeared to increase the earthy/dusty flavour, possibly due to the different precursors released by the greater skin breakage. The pre-fermentation addition of the water diluted the wine aromas, flavours and astringency profiles. However, combining the ACE technique with water addition enhanced the wine textural quality by increasing the intensities of the crucial astringent wine quality sub-qualities, adhesive and graininess. Furthermore, insights into the chemical factors influencing the astringency sensations were provided in this study. This research indicates that wine producers may use ACE with pre-fermentation water dilution to reduce the wine alcohol level but maintain important textural components. © 2020 by the authors.
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| 3. |
- Kang, W., et al.
(författare)
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Potato protein fining of phenolic compounds in red wine : A study of the kinetics and the impact of wine matrix components and physical factors
- 2019
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Ingår i: Molecules. - : MDPI AG. - 1431-5157 .- 1420-3049. ; 24:24
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Tidskriftsartikel (refereegranskat)abstract
- Producing wines within an acceptable range of astringency is important for quality and consumer acceptance. Astringency can be modified by fining during the winemaking process and the use of vegetable proteins (especially potato proteins) as fining agents has gained increasing interest due to consumers’ requirements. The research presented was the first to investigate the effect of a potato protein dose on the kinetics of tannin and phenolic removal compared to gelatin for two unfined Cabernet Sauvignon wines. To further understand the results, the influence of the wine matrix and fining parameters (including pH, ethanol concentration, sugar concentration, temperature, and agitation) were tested according to a fractional 25-1 factorial design on one of the Cabernet Sauvignon wines using potato proteins. The results from the factorial design indicate that potato protein fining was significantly influenced by wine pH, ethanol concentration, fining temperature as well as an interaction (pH × ethanol) but not by sugar content or agitation. Insights into the steps required for the optimisation of fining were gained from the study, revealing that potato protein fining efficiency could be increased by treating wines at higher temperatures (20 ◦C, rather than the conventional 10–15 ◦C), and at both a lower pH and/or alcohol concentration. © 2019 by the authors.
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| 4. |
- Kang, W., et al.
(författare)
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Dynamic characterization of wine astringency profiles using modified progressive profiling
- 2019
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Ingår i: Food Research International. - : Elsevier Ltd. - 0963-9969 .- 1873-7145. ; 120, s. 244-254
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Tidskriftsartikel (refereegranskat)abstract
- Wine astringency is important for quality and consumer acceptance. Perception of this mouthfeel is temporal and can be separated further into unique textural sub-qualities. Quantitative data on these astringent sub-qualities in wine however are poorly understood. The aim of this study was to characterize the dynamic astringency profiles of 13 Australian commercial red wines and 2 rosés made from 11 grape varieties using modified progressive profiling by a trained sensory panel (n = 8). Seven attributes generated and defined by the panel (overall astringent intensity and 6 sub-qualities: pucker, mouth coat, dry, grippy, adhesive and graininess) were scored at six time periods (each lasting 10 s), with 20 s gap between each time period. Attributes were rated on 15 cm scales with anchors at 10 and 90% and samples were evaluated in duplicate. The wine composition as well as phenolic profiles were determined. Intensities of astringent sub-qualities were correlated with overall intensity, but the sub-quality profiles at a specific evaluation period and the progression of an attribute varied differently depending on the wine. The discrimination of wines at each time interval was dependent on attribute, and the relative importance of each astringent sub-quality varied at different evaluation periods. Correlations between mouthfeel attributes and chemical measures were established. This study demonstrated the utilisation of modified progressive profiling for wine astringency evaluation, providing a tool to capture quantitative data on astringent sub-qualities in wine.
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| 5. |
- Danner, L., et al.
(författare)
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Dynamic viscosity levels of dry red and white wines and determination of perceived viscosity difference thresholds
- 2019
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Ingår i: American Journal of Enology and Viticulture. - : American Society for Enology and Viticulture. - 0002-9254 .- 1943-7749. ; 70:2, s. 205-211
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Tidskriftsartikel (refereegranskat)abstract
- Wine mouthfeel significantly contributes to the overall sensory perception and quality of wines. However, the influence of dynamic viscosity on the mouthfeel of dry table wines is still not fully understood. The three objectives of this study were to 1) determine the perceived viscosity difference threshold in wine using wine/xanthan gum solutions, 2) measure dynamic viscosity levels of Australian commercial dry Shiraz and Chardonnay table wines, and 3) investigate in wine samples the relationship between dynamic viscosity and chemical parameters, specifically, residual sugar, ethanol, and pH. A wine viscosity difference threshold value of 0.138 mPa·sec at 20°C was determined by ascending two-alternative forced-choice difference threshold tests with a sensory panel (n = 45). The dynamic viscosity for 34 commercial Chardonnay wines at 20°C ranged from 1.448 mPa·sec to 1.529 mPa·sec, and from 1.488 mPa·sec to 1.695 mPa·sec for 29 Shiraz wines. These results indicate that on the basis of the determined threshold values, tasters could likely differentiate wines in terms of viscosity within the viscosity range of this sample set of Shiraz, but not Chardonnay, wines. Furthermore, significant correlations between dynamic viscosity and ethanol concentration, but not for pH and residual sugar, were found for both varieties, indicating that ethanol may have been the main compositional factor that increased dynamic viscosity in commercial dry wines.
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