Grape Chemistry as of 9-2-12

Varietal

Date

Sugar (Brix)

pH

Total Acidity (%)

Primitivo

8-19-12

21.1

3.32

1.03

8-26-12

21.5

3.37

0.92

  9-2-12   (mean)

24.7

3.52

0.77

  9-2-12 (1)*

24.6

3.47

0.73

  9-2-12 (2)*

24.8

3.57

0.81

Tempranillo

8-19-12

19.4

3.48

0.54

8-26-12

21.3

3.63

0.46

9-2-12

22.2

3.58

0.42

Barbera

8-26-12

21.8

3.05

1.34

9-2-12

22.9

3.11

1.30

Touriga (Quinta)

9-2-12

20.4

3.33

0.69

*Two independent primitivo samples were collected and analyzed.

Comments:  Anticipating that we were approaching a critical time for the primitivo, we prospectively collected and analyzed two separate primitivo samples.  The two samples agreed on a surprisingly large increase in brix vs. last week’s reading, which may represent some combination of solid ripening, less irrigation proximal to the sample collection, and maybe a random low brix value last week.  The two samples were more divergent in their pH and TA levels, but the mean levels still showed a healthy rise in pH and large drop in TA, all consistent with ripening.  The large drop in TA would argue against mere dehydration accounting for the large rise in brix.  The bottom line for the primitivo is that we are at the brink of the optimal picking window, and harvest decisions can be driven mostly by logistical considerations at this point.  We would recommend harvest in the next ~5-10 days.

The tempranillo added about 1 brix and the TA dropped further, though the pH reading was unexpectedly lower than last week, perhaps reflecting random sampling error.  With no irrigation planned, the fruit should be pickable by next weekend, but with good bird protection afforded by netting, this could hold for an additional week.  We recommend harvest in 1-2 weeks.

The barbera showed incremental progress in ripening as measured by brix, pH, and TA.  We have been irrigating generously in the last week to prevent dehydration/raisining which might abrogate true ripening.  Late September still looks like the likely harvest window.

The first sample of the Quinta touriga was taken and showed pretty typical numbers for this varietal at this juncture.  Late September remains the likely optimal harvest window for the Quinta touriga.