A maturity trial study of Pinot noir wines : aroma profile by sniffing gas chromatographic effluent

Graduation date: 1991The quality of wine is highly influenced by the weather.\ud Temperature, solar radiation and humidity influence the\ud formation and concentration of aroma-active compounds and\ud aroma-active precursors in the grapes. Pinot noir grapes require\ud a slow ripening, under cool temperatures, in order to achieve\ud their fullest flavor. The main objective of this study was to\ud provide an overall aroma picture that could help, along with the\ud chemical indices, to decide the optimum harvesting time to\ud obtain certain distinctive aroma attributes in the wine.\ud This particular work represents the first stage in a broad\ud plan aimed to understand the dependence of the wine flavor\ud chemistry on the ripening of the grapes. This maturity trial\ud was planned to last several years; it was expected that the\ud outcome and techniques developed in the present study would be\ud essential in delineating the steps to follow. The results of the\ud aroma analyses for the 1987 and 1988 vintages are reported\ud here. In each vintage, Pinot noir grapes were harvested at three\ud different times, covering a range from early to late maturity.\ud A sniffing technique based on gas chromatographic aroma\ud detection by a trained panel was implemented. This technique\ud has proved to be a useful tool to measure qualities and\ud intensities of aromas. The method was effective in detecting\ud many of the aroma-active compounds and in identifying aroma\ud differences between the wines studied.\ud The aroma profiles for the wines were found to be very\ud different from each other within and across vintages. There\ud were only 10 aroma peaks common to all three 1987 wines, 16\ud aroma peaks common to the 1988 wines, and 4 aroma peaks\ud common to both vintages. Late maturity wines had more aroma-active\ud peaks than the other 2 wines for both vintages. The 1988\ud wines had a higher number of aroma-active peaks than the 1987\ud wines. The percentages of aroma-active peaks not detected by\ud the Flame lonization Detector (FID) were 45% in the 1987\ud wines, and 66% in the 1988 wines. The overall climatic\ud conditions in those years were very different. The 1987 season\ud was characterized as hot and dry, producing an early harvest.\ud The weather in 1988 was more of a typical season for Oregon,\ud producing a normal to late harvest. Further study is needed to\ud fully understand the flavor chemistry occurring during grape\ud ripening