The Sensorial Profile: Techniques

This is the time of year — at least for those making wine from grapes —when you get to taste and assess wines from this past vintage to determine how good these have turned out and what “tweaking” they require, if any. And if you are making wine from kits, this is a good time too.

Whites have finished fermenting and have been stabilized, perhaps even cold stabilized, and will soon be bottled; ditto for reds that will not undergo malolactic fermentation, although these are expected to age a while longer before going into bottles. And perhaps those luscious reds from past vintages that have been cellaring in oak barrels might be ready for bottling — for drinking or for further aging in bottles. Time to taste those too!   

Yes, it’s time to take stock of your wine inventory — that is, your wine that is in carboys, tanks or barrels — and decide if corrective actions are required on wine to be bottled, and which need more aging.  

So get ready to do some serious tasting and bench trials to try and optimize sensorial qualities of your wines. Here, we focus, not on faults, but on enhancing aromas, flavors and mouthfeel, or the overall experience that a wine is to provide. The “numbers,” or the wine’s chemistry, might look fine, but now it’s time to turn that good wine into something greater — a wine that will stand out at competitions — by letting your palate make the key decisions.

You will need to start planning your taste session a few days in advance. First determine your objectives based on your wine inventory; for example, if you have a lot of wines to assess, you may want to taste whites one day and reds the next. Keep in mind that you should taste a sample from every carboy, tank and barrel; the same wine in two different barrels — or even two carboys — may have turned out surprisingly different, and so it is best not to make any assumptions.   

Enlist a couple of friends whose feedback you value; you will want various opinions on the wines. Be sure to have plenty of glasses for each participant along with a spittoon and a jug of water for rinsing glasses and cleansing palates. Use a white table cloth to dress the tasting table.   

Pick a brightly lit room away from other distractions and noise; this is, after all, serious business. Plan the tasting on a day where you expect sunshine; it’s the best light for assessing color.   

The day before the tasting, collect a sample from each container. Pour samples in small flasks, 375-mL or standard bottles, or whatever else you have that can be stoppered or corked. Clearly mark each flask or bottle with the wine it contains; include the varietal, vintage, yeast strain, type of oak used and any other information you deem relevant. Place white wine samples in the fridge and leave the reds in the cellar.   

You will need a sugar solution to try different levels of “dryness” or sweetness. Prepare a 10% sugar solution by dissolving 10 g (0.35 oz) of sugar in 50 mL of warm water in a graduated cylinder, and then adding cool water to the 100-mL mark. You can scale this up if you expect to need more. Transfer the solution to a bottle and place a stopper in it.   

You will also need a “secret” ingredient — gum arabic. Gum arabic is a natural gum extracted from specific species of African Acacia trees and can be used for “rounding” out tannins in reds to reduce astringency, for increasing the perception of body or volume, or for reducing the perception of acidity. It is available as a dilute solution, for example, 20%.   

As you will be doing a lot of sugar and gum arabic solution additions, you will need 1-mL and 10-mL pipettes, a 100-mL graduated cylinder, or better yet, a
1000-mL graduated cylinder — you will soon realize that it is best to work with 750-mL volumes.

Tasting and testing
On the day of the tasting, organize the table setup with wine samples in the middle; taste whites before reds.   

Pour about an ounce (30 mL) of each sample of the same wine (from the various containers) into a separate glass. Assess each sample for color, aromas (smell), flavors (taste), mouthfeel, balance and finish. Record your notes and impressions for each, and after all samples have been tasted, discuss the results.   

Based on the feedback, decide on the kind of tweaking you want to try, and only perform one kind of fine-tuning (at different concentrations) at a time to assess the impact on the one improvement. For example, if you want to soften the acidity and add more oak, first perform some bench trials by adding different amounts of sugar solution to each sample, taste, zero in on the amount of sugar you prefer, and then, perform bench trials on that new sample with oak. Be sure to keep an unadulterated control sample for comparing to the other samples.   

Following is a list of tips on how to address specific enhancements. Keep in mind here that we are looking to enhance an already-great wine — we assume that there is no single major fault that requires fixing. And again, set the numbers aside (assuming that they do not point to any problems) and let your taste and palate guide your decisions.

Softening acidity:  Your fruity, citrusy Riesling or grassy, dry Sauvignon Blanc has a bit of a sharp edge to it? It’s amazing what just a little sugar will do to soften that extra tidbit of acidity. Even dry reds with a smidgen of aggressive acidity will benefit from a sugar addition. We are not talking about turning a dry wine into a sweet one, but rather, simply softening the acidity for a smoother mouthfeel. Try adding 1, 2.5 and 5 g/L of sugar to samples and compare each with the control. If, for example, 5 g/L makes the wine too sweet but 2.5 g/L is not enough, repeat the test with 3, 3.5 and 4 g/L until you achieve the desired balance.    The volume (X mL) of 10% sugar solution needed for your sample size (A mL) to add B g/L is calculated as X=A*B/100; for example, to add 2 g/L to a 100-mL sample (which will be poured into approximately 30-mL samples for three of you tasting), X=100*2/100=2 mL.   

Another trick to reduce the perception of acidity is to add gum arabic, as outlined below.

Adding mouthfeel: Your Cab seems a touch lighter-bodied or thinner than you would like? Here, you have two options: you can add grape tannins at a rate of 0.1-0.3 g/L (0.0135-0.04 oz/gal), but that is too hard to measure for small-scale bench trials, and so, the recommendation is to add a 20% gum arabic solution at a rate 0.5-5 mL/L (approximately 2-20 mL/gal) of wine. Start with a rate of 1 mL/L (4 mL/gal) and adjust up or down as desired; this requires 0.1 mL of 20% gum arabic solution in a 100-mL wine sample.

Softening astringency: Your promising Pinot Noir is a tad too astringent because of excessive or harsh tannins? You have two options: 1) add gum arabic as described above, or 2) try a PVPP fining by adding powder at a rate of 0.25-0.75 g/L, or as instructed by the manufacturer of the PVPP formulation you purchased. The advantage of a PVPP fining is that it acts quickly, and the processed wine can be retasted in as little as 1-2 hours.

Enhancing aroma and flavor profiles: One way to enhance aromas and flavors in wine is to fractionalize batches and to ferment those separately using different yeast strains; each imparts different sensorial profiles, which also depend on grape varieties and environmental factors. If you had planned accordingly and now have the same wine fermented with different yeast strains, great! Try blending samples from each batch in various combinations and permutations to see if the whole is greater than the sum of the parts; you may even want to try and blend different varietals altogether.   

And here’s another little-known tip: try and blend some white into a red. You want to turn that great Cab into a fabulous, memorable wine? Try adding, for example, up to 5% Chardonnay. Don’t overdo it though; that Cab should still look and taste like a Cab. And if you want to turn that fruity Riesling into a great rosé summer-sipper, try adding up to 5% of your favorite red, add a touch of sweetness, and round it all out with some gum arabic. There are no set rules when it comes to blending; experiment with different varietals and be creative.

Adding oak aromas and flavors: If your winemaking does not involve the use of oak barrels but you want to add further complexity to wine, this is the perfect time to run some trials with oak products. Even varietals known not to have an affinity for oak can benefit from a tiny oak influence when properly balanced. You can now get oak as a powder, shavings, chips, cubes or staves, in French, American or eastern European oak as well as in a variety of toast levels from light to heavy. Unless you have a specific preference based on past experience, you will need to test extensively here to find the right oak product for your needs. Each product will impart a different sensory profile and at a different rate, all of which depend on the varietal at hand. And bench trials with oak will take days or weeks, and so, you need to plan carefully and taste often. Be careful as it is quite easy to over-oak wine. Follow the instructions provided with the oak product.

Putting it all together
Once you have concluded your bench trials, prepare a couple of bottles of wine using the formulation you determined, and set the wine aside in the cellar for a week to one month to give it a chance to “settle down.” Then retaste the wine to ensure that it tastes as it did from the bench trial session; if not, make adjustments as necessary, but these should be minor at this point.   

If the wine is as per your bench trials, you are ready to process the whole batch. Double-check the formulation, and measure ingredients twice before adding them to the whole batch. All of the above tweaks should be performed on fully stabilized wines, after the final fining or before final filtration prior to bottling.   

And remember, wine will always benefit from further aging after you have made  the desired adjustments. Don’t be tempted to rush the aging process, but do remember to taste the wine on a regular basis to see how it is evolving.

Daniel Pambianchi is General Manager of Maleta Estate Winery and author of “Techniques in Home Winemaking” (Véhicule Press, 2008).