Quantitification of Microbial Rot in Wine Grapes

AVF Proj. ID: 506 / /Cat.:
Primary Investigator(s): Roy J. Thornton, Susan B. Rodriguez, Gary Takeokaby
  1. There was good agreement between the samples collected from the vineyard by hand and the samples taken at the sugar stand in Livingston for Chardonnay grapes.
  2. The Chardonnay calibration is very strong, representing nearly 500 samples taken over three very different vintages from vineyards in Bakersfield to Lodi.
  3. Work has begun on a four-mold calibration that includes Botrytis in addition to the other three molds. Good R2 values were seen for both Chardonnay and Zinfandel.
  4. PLS regressions of Cabernet and Merlot individually and combined gave high R2values.
  5. A PLS regression that combined Cabernet, Merlot and Zinfandel gave an R2 of 0.98, suggesting that a single calibration for red grapes is possible.
  6. When the PLS regressions of Chardonnay and Zinfandel samples over three years were combined, the R2value dropped to 0.82, but it is still a solid model.