Author: Scott Clifford FrostPublisher:
ISBN: 9781369615838
Category :
Languages : en
Pages :
Book Description
The presented work aimed to explore the chemical and sensory relationship of red wine astringency. Two sets of experimental Merlot wines were utilized. The first set of wines were produced at the Washington State University Irrigated Agriculture Research and Extension Center (WSU-IAREC), then sent to UC Davis for chemical and sensory analysis. This set of wines employed a factorial design to evaluate the relationship of tannin, acid, and ethanol concentration on astringent perception. The factorial design allowed for evaluation of the effect of each factor on the response variable. Descriptive analysis (DA) and temporal dominance of sensation (TDS) were used to describe the sensory response. A five-factor analysis of covariance (ANCOVA) was applied to the DA data. The results showed significant effect of tannin and acid concentration, but ethanol concentration was not a significant effect. The analysis of the TDS data was dictated by the ANCOVA results. TDS curves were constructed by factor level only for significant effects as shown by the ANCOVA. The use of a factorial design for the analysis of TDS data was novel. These results are contained in chapter 2. The second set of experimental wines were produced at The UC Davis Teaching and Research Winery. These wines focused on altering chemistry and sensory through winemaking. Nine cap management and extended maceration treatments were evaluated. Extended maceration was applied to c.v Merlot grapes for 1, 2, 4, 6, and 8 weeks. In addition, a punch down treatment and two submerged cap treatments were also evaluated. The treatment effects were characterized using descriptive analysis, polyphenol measures, basic wine parameters, and volatile analysis. Length of extended maceration defined the astringent texture of the resulting wines, while bitter taste and pepper spice aroma were defined by the type of cap management. The chemical and sensory results relating to winemaking are presented in chapter 3. The fourth chapter explores the relationship of descriptive analysis and temporal dominance of sensation. The DA and TDS results from the maceration experiment are utilized to compare and contrast the two sensory techniques. Similar results were shown between the DA and TDS results for “hot” taste, but maximum dominance rate for astringency and bitter were not correlated with maximum DA intensity. In addition, correspondence analysis was applied to the TDS frequency table in order to project the results into a multivariate space.
