The Grapes Are In...Now What?
Learn how three seasoned winemakers handle fermentations, including the challenges of high sugars, nutrient additions, timing, testing and spoilage.
By Lance Cutler
From Wine Business Monthly, 10/01/2004
These winemakers were less combative than the previous group, although they had their own concepts of how to extract the best results from fermentations. I was looking to discover how they dealt with fruit once it arrived at the winery, and how much they were manipulating the fermentations with additives or technique.
In attendance were Karen Ernsberger, associate winemaker, microbiologist and port winemaker for Benziger and Imagery wineries, who has 25 years' industry experience, including stints at Buena Vista, Simi andGrand Cru; Marty Bannister, who produces wine under her Bannister Wines label and co-owns Vinquiry, has been providing lab services to the wine industry for 25 years; and Nils Venge, a winemaker since 1973 who runs his own Saddleback Cellars and consults for Keenan Winery, Del Dotto Winery, Plumpjack and B.R. Cohn, among others, and has been seminal in the development of Villa Mt. Eden and Groth.
Has the higher pH and sugar affected the temperatures at which you are fermenting?
Ernsberger: Not on whites but on reds. Along with higher sugars, there tends to be more raisining and dehydration on the berries, so we have to really watch how high the temperature goes. It's also based on what the sugar is. If the sugar is 26° Brix, we try to keep it at 85° F. If it's at 27° Brix, we keep it at 80° F. We add 50 ppm of SO2 for all of our reds. For our native fermentations, we adjust to 40 ppm and keep it there so we can knock down unwanted yeasts and let the sacchromyces yeast become more prevalent. They're cold-soaked for two to five days to improve mouth feel to let the tannins marry with the juice. It allows the soft tannins to come out. We do some maceration afterwards as well, depending on the variety, possibly 22-26 days on the skins.
Bannister: Timing is important with the addition of nutrients. For example, you should not add nutrients during a cold soak. You want to add them when your indigenous population is up and going, or when you're adding your yeast.
Ernsberger: We add nutrients in four portions during pump-overs or punch-downs after the fermentation has kicked in.
Venge: If it is my problem child Zin with its high sugar (26.5-27° Brix), low pH and high acid, then we'll add water to lower the sugar level. I shoot for 25.5° Brix so I can sleep at night. At first pump-over we add Montrachet yeast. I don't mind going up to 85° F or even 90° F to help blow off some of the alcohol. With the Cab, I'll hardly ever need to add any water. I tend to add acid to the Cab. I'd like to see it at 6.5-7 if possible. The pH at that level is wonderful for our area. When I finish out, it's 3.4 or 3.5, which is great.
Ernsberger: We're making a lot fewer acid additions. Particularly the past two years. We've seen lots of high acids and high pHs, so we don't add acid to lower the pH because the acid is already high.
What is it you're trying to do, or correct or achieve with these additions, and how do you best think you can do it?
Ernsberger: For us, we need to have our ammonia and NOPA number (alpha amino nitrogen), and we also know how dehydrated the grapes were. That, with the sugar content, acid and pH gives us a feel for the must. That gives us an idea of how much we need to bring up the nitrogen level. Again we only add after the yeast has been in the tank for one or two days. In the case of indigenous yeast, it's probably five-to-seven days. We use yeast hulls, yeast extract, certain vitamins like Cerevit, organic compounds and minerals.
Bannister: Cerevit is a B-vitamin mixture, which helps the yeast remain active and reduces hydrogen sulfide. The main target with nutrient additions is to get fermentations through without sticking. So it depends on what is in the must to begin with. We do the testing and then add the needed amount of nutrients. Years ago we worked with lower Brix levels, so we used lower amounts of nutrients under those conditions. The longer the grapes are on the vines, the more depleted they are in the nutrient material, and that has added to the need for nutrients. So there are a number of broad-based nutrients that have high amino acids for that purpose. If they are really deficient, then DAP can be added.
Venge: I just add Superfood and DAP. If I know the vineyard has had problems in the past, I'll add pretty religiously. With the Cab, it's all my own fruit, and I've never added anything.
What can go wrong with the addition of nutrients?
Ernsberger: If you add too much, you end up with more H2S and mercaptan characters being formed. Particularly when adding DAP in large amounts at the very beginning. I think it helps to break up the additions over the course of a couple of days rather than dumping it all in at once. We're seeing less H2S production by not adding it all at once.
Bannister: Timing is important here also. You don't want to add nutrients after the yeast can use them. You need to add them while they are growing. I think 15° Brix is about as late as nutrients should be added.
Ernsberger: We've gotten down to 10° Brix, but we don't add later than that; and because we add in portions, we've already got most of it in before the Brix gets too low.
So, has the science of these nutrient additions come about largely because we pick at higher sugars, and the key intent is to finish the fermentations to dryness?
Bannister: Even before the sugars started going higher, there was also this separation of grapes into lots. Individual lots tend to have nutrient deficiencies more than big, blended lots. If you start combining a bunch of grapes from different vineyards and put them together for one fermentation, they'll tend to balance each other, whether it's the amino acids or specific nutrients, so those fermentations tend to go better than individual lots. These problems go back a long time. So working with riper grapes just adds another dimension in trying to get over this high-alcohol hump.
What are the essential tests that you need to run during crush?
Ernsberger: Brix, pH, TA, malic acid, ammonia and NOPA. We may also do SO2 because picking grapes with sugars so high requires that we add SO2 so we don't get lactobacillus taking hold. Occasionally, we'll do microbe scans.
Bannister: That's about the same as we recommend. The essential tests would be Brix, TA, pH, temperature, ammonia and Karen called it NOPA, but that's the assimilable amino nitrogen. Then for lots that need additional illumination, acid profiles to break out the malic and tartaric acid, and potassium because it will have an impact on the pH and give a sense of how much the acid might shift during fermentation. It's a winemaker preference. The basic things and the acid profile would be included in what we call a "juice panel." What we've seen in the past is that sometimes winemakers will run the whole panel for a while until they get comfortable with the vineyard, and then they might go back to a simpler version.
Venge: I run Brix, pH, TA and malic, but then on hillsides I will go ahead and run an ammonia, but when you take a test, there's also the human test. That's how the skins are tasting and the maturity of the seeds, and that's just as important to me as going ahead with analytical tests in the lab. We want the skins to be pliable and have a uniformity of maturity just from the look of the grapes. I'll go ahead and accept a berry or two that are still green and immature in there because I know that most of the time they're just going to pop out of the crusher and never get crushed anyway. I want to see a good percentage of dark seeds. I squish up my berry samples in those little sandwich bags, and I want to see a good percentage of brown seeds. And I like to see a little pinking of the juice in the bag, so there's a color test for me as well.
Okay, so the grapes come in. What are you going to do?
Ernsberger: For whites we like them to come in at not more than 24° Brix, and then we will adjust them down to 23° Brix because we're trying to stay under 14 percent alcohol. Then we look at all the parameters: Brix, TA, pH, malic. We run ammonia and NOPA. Sometimes we add SO2 if the juice is going to sit for an extended time before fermentation, otherwise we don't. We add yeast after the adjustments.
Bannister: SO2 addition depends on style and intent. To some degree in whites it depends on pH. With high pH there would be call to add SO2. With reds we definitely recommend that people add SO2 at crush because over the years we've seen so many people get burned by microbial spoilage. Because making white wines without SO2 worked so well, that technique got transferred to red wines. Then over a period of years, you could kind of see it go winery to winery. They would be okay for a period of years, but pretty soon they'd start having problems with microbial spoilage, maybe because of a population buildup in the winery. Eventually, bacterial growth in the red wine fermentation would result in very high VAs (volatile acidities). So we would always recommend SO2 in the 30-50 ppm range. But that's off of the white wine discussion. We suggest running ammonia and nitrogen because there's such a range of nutrients in different juices, and we don't recommend that people just add nutrients automatically. We'd rather have them know what they've got.
Venge: For whites I'm whole-cluster pressing right away. I've found that early browning of the pressed juice disappears post fermentation. With the Pinot Blanc, I'll add SO2 but only after 36 hours of cold settling. At that racking, I'll go ahead and add the SO2 and the acid if I need to. We'll bring must up to 50 ppm free. I add yeast. I'm not a believer in whites undergoing a long natural fermentation. With all the varietals I'm doing, I need that tank space. So after that cold settling at 45-48 degrees, I'll rack to another stainless tank and start the yeast addition. It may take another day to get up to about 52°F before fermentation kicks in. At 14° or 12° balling, then I'll shoot it right into the barrel and let it ferment to dryness.
What are the ramifications of picking at higher pHs, and what can we do about them?
Bannister: The higher the pH, the faster bacteria will grow. If you are getting grapes up to 3.6 or especially 3.8 to 3.9, problematic bacteria can grow really rapidly and create spoilage very quickly. Lactobacillus is a particular problem. A lot of wineries have experienced problems with rampant spoilage from Lactobacillus, indigenous either to the grapes or the winery, and during fermentation, overrunning yeast and causing spoilage. SO2 helps. Lowering the pH helps, and then a product that has become fashionable in the last few years is Lysozyme, which is a bacterial inhibitor extracted from egg whites.
Venge: And you have to go through the BATF to ask permission to use it. They won't deny you; they just want to know. So you have to be prepared ahead of time.
Ernsberger: It lyzes (ruptures) the bacterial cell. It works against lactic acid bacteria, not Acetobacter. It works against Pediococcus too. So the ramifications of having higher pH from a winery standpoint is that you are going merrily along with your primary fermentation and it stops. It could be stuck at 2-3° Brix, or malic acid may start to be consumed by one of your lactic acid bacteria. This is where using Lysozyme helps. We start checking our volatile acidity as soon as we notice a slowdown to make sure it is not something of that sort happening. But we have certainly had spontaneous malolactic fermentations complete before the sugar does, which generally causes stuck fermentations.
What aboutleaving wine on the yeast?
Ernsberger: It adds mouth feel.
Venge: It's just like Champagne. After I had a few years' experience back in the 1980s, I said, "Wow, this is nice." It just added roundness in the aftertaste.
Bannister: It works on Chardonnay and Pinot Noir.
Venge: Yeah. I'm not doing it on the Cab or Merlot.
During fermentation there's a lot of rack and return, splashing and pumping over in an attempt to oxygenate the must. Do you think that works in light of all the CO2 present?
Ernsberger: There has to be some oxygenation. We usually will incorporate a splash rack or rack and return if there's a bit of stinky sulfide character. The oxygen certainly seems to help the yeast in some respect. This is macro-oxygenation rather than micro-oxygenation. We use it mostly for Cabernet, Merlot and Syrah.
Venge: It seems to make the wine fresher and fruitier.
Bannister: It is a technique that came about primarily with the Rhône varieties, and it made the Rhône varieties more approachable. Now for yeast, yes. The yeast need oxygen, and they will definitely ferment better. That's not the only thing to think about, though. You must consider what is happening to phenols in the wine and how those are responding to the oxygen. It's very desirable for the yeast, but I think you have to look at what it is doing to the rest of the wine.
Are you using micro-oxidation?
Ernsberger: We do a small amount after fermentation, not during. And we've been doing it after malolactic. We tried it prior to malolactic, but those particular wines went right through. It's an interesting process and has its applications.
Bannister: I think it's totally dependent on variety, the intensity of the particular grape and the style desired. It's not a single technique for all types. For example it's great for Syrah, but in my view it would not be good for Pinot Noir.
I once had a theory that if during the fermentation process you could get everything off the seeds, it would help reduce the bitterness.
Bannister: Absolutely, and that's one of the things people are using the rack-and-return system for.
Venge: Up at Keenan we call that "seed management." It's one of our little techniques. We drain through a screen into the tub during pump-overs, so we are removing them everyday. We press off around five balling.
Bannister: That's where a lot of phenols come from, the seeds. Choosing when to press and when to remove seeds can have a great impact on the final bitterness in a wine.
What is the biggest change in winemaking since 1980?
Ernsberger: I think the biggest change is that we're going for mouth feel.
Bannister: When we made wine in the 1980s, it was the technical, whiz bang things you could do to make wine, like using a centrifuge. In terms of current winemaking, it has retreated to more traditional methodologies.
Ernsberger: Bringing back punch-downs and more traditional philosophies.
Bannister: Technology is now being used to understand and monitor the process.
Speaking of technology, is it better to build your own malolactic culture or to simply direct add?
Bannister: Building is work, but the additional character it adds is worth it for the people who can do it. If the bacteria grows in the wine, then you get more of the character of that bacteria in the wine than the direct-add bacteria. When you use the direct-add bacteria you are adding enough cells to complete the malolactic fermentation, but they don't really grow in the wine. They are not characterless; they impart some, but not as much as the bacteria that actually uses the nutrients in the wine.
Venge: Some of my clients build up cultures, but I just wait for it to occur in the barrel. It lets me keep the SO2 low in the winery since the wine is still giving off CO2. I try to keep them around 20-24 free. My bugs hold up to that level of SO2.
Ernsberger: In our biodynamic program, we don't add any SO2, we let it go through malolactic naturally. It might be May before we get any SO2 into those wines. We check VAs and malics. We haven't had any problems as long as the wines are dry. With sweet wines, not having SO2 can be a problem. The slower the malolactic fermentation, the better the mouth feel. There's a marrying of flavors.
What about filtration?
Ernsberger: It oscillates whether people are filtering or not. We certainly try not to do much filtration if possible. We sterile-filter the white wines because they haven't all gone completely through malolactic. Sweet wines we still sterile-filter. With the red wines we try not to at all.
Bannister: I think in red wines Brettanomyces is the biggest problem. That's an area where there isn't real good control without filtration. If you've got it--and who doesn't--you can keep it under control by maintaining SO2 levels and having the wines be as dry as possible. But even so, there frequently is some, and even if there are extremely low levels going into the bottle, then there is some chance of growth leading to off aromas and flavors. Culturing is necessary to monitor Brettanomyces. Four-ethyl-phenol is the major compound we check. At least before bottling.
Ernsberger: We're plating the wines three or four times a year, and then we do our initial four-ethyl-phenol test almost one year after harvest. We do another batch in December to see if there's been a bloom during harvest. They tend to go up higher during warmer seasons. Then a couple more times before bottling, and if there is a rise, we'll adjust our filtration based on that. Also we check the VA; if it's rising, that's another indication that we'll need to filter. We don't do sterile filtration; an S-50 pad is about as tight as we'll go.
Venge: Like Karen, after summer we'll check the previous vintage. Then I'll examine one more time about a month prior to bottling. And sometimes again in the tank where you get a really good sampling because you can get a lot of variations from barrel to barrel.
Bannister: Yeah, I think getting a good composite sample is critical for culturing because you do have gradients and organisms tend to accumulate at different levels in barrels.
Venge: On my whites, it's all sterile-filtered because they don't undergo malolactic. For the reds it's certainly an important test. But I don't get all upset when the analysis is under 100 parts. It's just a manageable thing that could actually add to the attractiveness of the wine, so I'm not going to say we've got to sterile-filter this. But with the reds it's certainly a very important test. If I'm down at a nice low level, I'll just have a polish filtration and it really helps brighten up the taste.
As a winemaker, what is the most aggravating thing you have to do?
Venge: The paperwork. It seems like everywhere you turn you're looking at one regulation or another that you have to be mindful of. Also staying competitive in the marketplace requires more of my time on the road to work in each market.
Ernsberger: Most aggravating to me is stuck fermentations.
Bannister: I always think it's bottling because nobody ever got into the wine business to bottle. All the thinking and attractive parts of winemaking happen before the bottling, and then it's just tedious. It's a job as important as anything else you do in the whole place. It's sort of your last chance to get it right.
The basic rule of winemaking remains that for everything you do there is another consequence, which begets still another consequence. Waiting for higher sugars may lead to riper flavors and smoother tannins, but it also creates higher alcohol and can make malolactic fermentations a challenge. Getting oxygen into the fermenting must will make the yeast happy, but can also activate other organisms that are not so friendly. Certainly, each vintage affects each vineyard in mysterious ways that change from year-to-year.
Our panelists point out that it behooves every winemaker to find out as much as possible about the grapes we're working with and to judiciously use that information when formulating nutrient additions. It is a good idea to have a plan, even if you get too busy to carry it out. We should assist the yeast and malolactic bacteria to do their duty, knowing full well that some fermentations are going to stick no matter what we do.
Finally, even a panel with close to 90 years' experience can't predict a harvest. We might as well enjoy ourselves and go with the flow, knowing that we will probably win some and lose some. It's been that way for centuries; it's not about to change now. wbm
We addressed the current trend of picking grapes at high sugars in the first "Winemakers on Wine" (WBM July 2004), and talked about parameters for ripeness and the reasons for letting the grapes hang. In this edition, I wanted to delve into winemaking techniques, with particular emphasis on the handling of fermentations, especially given the higher sugars most winemakers now encounter.
Lance Cutler is known as one of the "wild men" of the wine business. He hijacked the Napa Wine Train, kidnapped Richard Branson and a busload of reporters, and helped force humor on a stodgy wine business. He is the winemaker for Relentless Vineyards and the author of The Tequila Lover's Guide to Mexico and Mezcal, Making Wine at Home the Professional Way and the Jake Lorenzo books. Check out his website, www.winepatrol.com.
The basic rule of winemaking remains that for everything you do there is another consequence, which begets still another consequence.