Grape chemistries taken on 8/30/09 show incremental progress in ripening across all varietals.
Acid has come down but remains quite high in the barbera, while sugar begins to creep up. We continue to anticipate a late September harvest. The fruit is generally in excellent condition; we see some wrinkling suggestive of dehydration in a very small minority of clusters. We continue to irrigate the barbera proactively in light of the hangtime that will be required, and Mother Nature–at least per current weather forecasts–is actually cooperating this year by providing moderate temperatures (low 90’s) into the foreseeable future. Seconds have been dropped in all of block 1 and most of block 2, and the plan is to drop as many of the remaining seconds as possible in the coming 2 weeks.
The primitivo vines look especially tired early this year for reasons unclear, so we called an audible and conducted a second round of cluster thinning this past week to ease the burden of ripening, dropping clusters that were visibly behind the ripening curve. The fruit is generally in excellent condition, with no signs of dehydration at this point. It would appear from the chemistries as well as the relatively light color of juice in samples that we are still approximately 2, or at most 3, weeks from optimal harvest time.
The Portugese varietal grapes are looking very good. We have managed to largely keep the birds away from their favorite grape, tempranillo, which is on track for harvest in 1 to 2 weeks. In the past 10 days, we cluster thinned both the tinto cao and touriga nacional grapes, which it became obvious (with full veraision) were carrying more fruit than we thought they should.
Where Do the Grape Chemistry Data Come From?
If you think that the grape chemistry data at Shaker Ridge are delivered by a stork or left by the grape chemistry fairy, think again! About once a week as harvest time approaches, we attempt to get a snapshot of ripening in our vineyard by gathering objective data. One of the first things the co-proprietor at Shaker Ridge learned in graduate school laboratory is that one can either do an experiment right the first time, or spend a bunch of time trouble-shooting why it didn’t go right, then repeat it. It quickly became obvious that it was more efficient to do it the right first time. And doing it right the first time in scientific endeavors often comes down to careful attention to detail and following a set protocol. Our grape chemistry data is accordingly gathered in 3 systematic steps: sampling of the vineyard, processing of the samples, and testing of the samples.
Grape sampling is arguably the hardest and most important step. For sampling, we walk up and down vine rows the entire length of a given vineyard being sampled, alternately taking bunches of grapes from the top, middle, and bottom of plants chosen at random. We try to visually identify the bunch to be sampled while still some distance from the plant so that we end up getting a representative sample of what’s out there, rather than what we’d LIKE to be out there. Unless a bunch is so visibly unripe or overripe (shriveled) that it wouldn’t reasonably be taken by a crew in a real harvest, we take it. We sample entire bunches, rather than individual berries, since it’s ultimately the whole bunch that would be harvested, and picking individual berrries would open us up to many potential sources of bias. We end up with 10-15 pounds of grape samples, which when carried around in a bucket up and down hills on the typical 100-degree late summer Foothills day turns into a decent workout….This is repeated separately for each varietal being sampled.
The next step is sample preparation, and for this we use a stainless steel fermentation punchdown tool to crush and squeeze the grapes in the same buckets in which they are collected. The tool is cleaned between each sample. Once the grapes are well crushed and juice is abundant, we pour about a cup of juice through a stainless steel wire mesh filter (to catch pulp, seeds, etc.) into labelled plastic containers, one for each variety or block sampled.
In the third step, the juice samples are tested, typically immediately after their preparation, or at most a few hours later. The samples are first tested for sugar using a hydrometer. The raw values are manually corrected for juice temperature, which is collected simultaneously with the brix reading. Using a digital pH meter that we calibrate with appropriate standards immediately before each session, we then record the pH of each sample in turn. Finally, we perform a a manual acid titration, fastidiously cleaning syringes and vessels between samples, to determine the total acid content. Tests aren’t repeated unless a known technical error is made, or an overt inconsistency is noted.
While we reserve the right to root for particular outcomes (!), we record and report the data that we get. Besides the objective measures of brix, pH, and total acidity, which we post on this website, we also record more subjective but valuable information about taste and color of the juice samples that help confirm that we are testing the varietals that we think we are, and provides a useful cross-check/sense check against the numeric data.
The entire process of sampling, processing, and testing takes upwards of 2.5 hours, depending on the number of samples, which hopefully explains why we don’t provide daily updates! We hope that our attention to detail in the generation of the grape chemistry data translates into better harvest decisions for our clients.