Book Description

The impact of mechanical harvesting, optical berry sorting, and the synergistic effect of both on grape and wine composition were investigated. Pinot noir grapes from the Russian River Valley A.V.A. were harvested by hand, by a mechanical harvester, and by a mechanical harvester with an on-board sorting apparatus. For each harvest method, half of the grapes were unsorted and half were optically sorted at the winery. Wines were made from each treatment in triplicate. The grapes, wines at bottling, and wines after three months in bottle were analyzed by reverse phase high-performance liquid chromatography (RP-HPLC), ultraviolet-visible spectrometry (UV-Vis), and solid-phase microextraction (SPME) gas chromatography mass spectrometry (GCMS). The machine harvested grapes had higher levels of damascenone, linalool, myrcene, and terpinene, likely due in part to increased enzymatic glycosidic hydrolysis caused by berry damage during harvest. In general, differences in wine composition that arose from harvest type were diminished or eliminated with the use of optical sorting. The machine harvester with the on-board sorter led to wines with the greatest phenolic content, though it is suspected that these differences may have been eliminated had the grapes been crushed before fermentation. A descriptive sensory analysis that was conducted on wines three months after bottling showed that the wines made from hand harvested fruit had significantly greater tropical fruit aroma, while wines from optically sorted treatments had lesser hue saturation. With only two significant differences among the 18 aroma, taste, and mouthfeel attributes tested, it was concluded that all treatments led to wines of similar character.