Berry Sensory Analysis: this winemaker's favorite harvest tool
(A slightly modified version of this article appeared in Montemaggiore's September 2014 Newsletter)
The 2014 harvest is rapidly approaching, and this is when I start getting nervous. Choosing the exact day to harvest the grapes is a winemaker’s most important decision, but there are a lot of factors to weigh—and the most important factors tend toward the art of winemaking as opposed to the science. Metrics such as pH, Acid, and Brix (sugar level), are easily measured objectively—but at Montemaggiore, we don’t pick “by the numbers”. The most important factors I use to determine when to pick are flavor and tannin ripeness, and these can only be assessed by the winemaker’s mouth. Since I’m always asked about how I “taste ripeness”, I thought you might appreciate taking an in-depth look at my favorite tool to measure the seemingly unscientific concept of grape maturity: Berry Sensory Analysis. While this is my most important tool, it is just one, single tool. The vines' photosynthesis capabilities, upcoming weather, and availability of picking crew are also considered in making picking decisions.
About two weeks before harvest (which I guesstimate by un-rigorously tasting random grapes in the vineyard), I start applying Berry Sensory Analysis. This technique was developed by Jacques Rousseau of Institut Coopératif du Vin, a prestigious consulting firm in France. Its beauty lies in its rigor, repeatability, and accuracy—especially given that it relies on something as unquantifiable as a winemaker’s taste.
As with any analysis, the accuracy of Berry Sensory Analysis depends on the data utilized. Thus our first step is venture out in the vineyard and collect a representative sample of the grapes. While Vincent has divided our 10-acre vineyard into seven blocks for irrigation purposes, I have divided it into 12 different sub-blocks which I know from prior experience ripen at uniform rates. I analyze each of these 12 sub-blocks separately for grape maturity and ripeness—and we pick each sub-block separately (although on any single harvest day, we may pick more than one sub-block). Most larger wineries would not have such a granular look at their vineyards—but being small means we can target the desired ripeness of our grapes more precisely because we’re harvesting smaller areas separately.
In each of our 12 sub-blocks, I have marked two or three specific rows that I feel accurately reflect conditions in the entire sub-block. I only sample grapes from these particular rows. In each row, I gather my sample from ten to twenty different bunches, half from each side of the row. From each bunch, I take five individual berries: one from the middle sunny side, one from the middle shady side, one from the top front shoulder and one from the top back shoulder, and a fifth from the bottom tip of the bunch. Thus I have a statistically-relevant sample of 100-200 berries from each sub-block.
Armed with a really good sample, the second step is to analyze the grapes back at the winery. I randomly select 3-4 berries from my overall sample—and assess them as a group according to four ripeness criteria:
- technological ripeness
- pulp ripeness
- skin ripeness
- seed ripeness
Fundamental to this analysis is being able to separately taste and analyze the pulp, skins, and seeds because the sugar in the pulp, for example, can alter one’s perception of the skin flavors. This separation can be done in your mouth, all at once, given a little bit of practice and tongue dexterity. I pop 3-4 berries in my mouth, then gently crush them between my tongue and roof of my mouth—meanwhile assessing the technological ripeness and pulp ripeness. Then I spit out the seeds, and chew on the skins fifteen times to assess the skin ripeness. Finally, I look at the seeds and pop them back into my mouth to crush and taste them. Then I repeat this analysis three more times for a total sampling of 12-15 berries from each sub-block, and record all my findings in a spreadsheet.
Each set of berries receives a score from 1-4 for each of the four ripeness criteria (1 being less ripe and 4 being ripe). For my style of red wine, I’m looking for all 4s which translates to:
Ripeness scores of 1 through 3 have similarly precise definitions (full score sheet). And the scores are 1 to 4 for a reason: if they were 1-5, one might be tempted to gravitate toward 3 in too many cases, whereas the scale of 1-4 makes one choose between 2 (less ripe) or 3 (more ripe). Likewise decimals and fractions aren’t allowed because then the scale wouldn’t be 1-4, it would translate to 1-40.
The last step in the analysis process is to make some decisions about when to pick and/or when to perform the next analysis. Assuming our vines haven't started going into their winter dormancy, grape sugar levels aren’t getting too high and no rain is forecasted, then we will only pick when 4s are reached. Once a vineyard sub-block reaches that optimal level of ripeness, I will ask Vincent to schedule harvest as soon as possible, typically within 2-3 days. If the target area is not quite ripe, I will look at the information from the last time I performed Berry Analysis or perhaps even in prior years, to estimate when I’ll be harvesting that area. Finally I’ll decide when I’m going to sample the area next to repeat the entire analysis.
Do the flavors in the pulp and skins and seeds translate into flavors in the in the wines? Not directly, because many of the flavors we enjoy in wine are only present in undetectable forms in the grapes. A fermentation process is required to unlock these flavorless precursors and bring about the heady aromas we love. There is, however, an indirect correlation between skin flavor and wine flavor for example. A winemaker who has experience with a vineyard can certainly make correlations between level of ripeness and flavors of the resulting wine. Since we have had experience with our estate vines for the past 13 years, I know what the wine from one particular sub-block will taste like if the tannins are slightly underripe, and I know what the wine from another particular sub-block will taste like if the skin flavors are slightly overripe.
Berry Sensory Analysis allows me to accurately and repeatably assess the grape ripeness, thus achieve my desired “Montemaggiore” style of wine. If for some reason the grapes could not be picked at optimal ripeness, this Analysis will arm me with data to choose the winemaking techniques that can mitigate the situation.