Couldnt agree more, Keith. Botrytis and the ensuing laccase (the enzyme associated with the rot) are often responsible for making wines with many of the vibrant, fruity flavors listed above. However, all it takes is a tasting of wines (both red and white) from a region and vintage that suffered through torrential harvest-time rains to identify the unpleasant, wooly character of Botrytis in wines not meant to be made in the “botrytized style”. In the past year alone I’ve dealt with this in with the 2009 Napa Cabs and the 2010 wines from New South Wales. Think: spilling wine on a wool sweater and sucking it up from the stain.
For me, botrytized wine have a honeyed flavor and texture with apricot/peach flavors and bitterness I associate with citrus pith/peel.
Considering the level of the discussion that is ongoing, would you perhaps like to support your statement in depth?
Interesting. Wooly is a term associated with Loire Chenin Blanc. I wonder if this is really a matter of Botrytis affecting less ripe fruit given the climate and proclivity of Chenin to produce Botrytized dessert wines.
Kim –
Like everything else with wine, the best, and least satisfactory answer, is that it depends. I’ll try to explain the little bit I know and maybe clear up some erroneous information. There seem to be some misconceptions regarding what happens. It’s true that a lot of what we taste is a result of what happens as a result of the botrytis, but it’s not true that those things are hidden by the aromas and flavors of the grapes themselves. The botrytis effects are distinctive. And the botrytis itself is also distinctive, separately from its effects.
First, look at what botrytis does to the grape. Some things are going to happen normally as the grape matures, some won’t happen unless you have botrytis. You need to start out with the right grape – if the skin is too thick for example, you just get rot and not a good botrytized grape. But assuming everything else is in place, the botrytis punctures the grape skin. This allows the mold to suck up the juice but it also allows for evaporation. At the same time, the grapes are generally near or at maturity and a natural event at that time is the failing of connective nutrient systems that tie the grape into the vine. The botrytis accelerates that. So a few of the things that are taking place include punctured skin, loss of water and nutrients, no way to replace those, and on top of that you’ve got a growing colony of mold.
The mold itself eats up a lot of the sugars that are in the berry. But there are different types of sugars, or saccharides, some of which are synthesized as a result of the mold. So even though the mold eats up a good portion of the sugar, the loss of moisture concentrates the remaining sugar, resulting in a sweeter berry. In fully infected berries, you end up with somewhere around twice the sugar by weight in terms of grams/liter. Also, some of those sugars are very complex and along with various glycols and such, they give a thickness to the wine, changing its texture, as well as adding their own flavors.
Some compounds also inhibit the action of the yeast, but that’s a whole different topic. Just as an aside, the people who go on and on and on about indigenous yeast and all that crap should really be having a field day with botrytized wines because there are many variations of botrytis – it’s not like there’s one single botrytis for the whole world. And depending on the fungus, it can either inhibit or enhance the activity of the yeast. More importantly, I’m not aware of commercial strains that are available for infecting grapes on the vine, so it’s almost always “indigenous”, although there has been work done on infecting picked grapes in the winery itself.
The mold also causes sythesis of something called sotolon, which is also found in savory foods and which is partly responsible for the unique aroma and flavor of botrytized wines. It’s also found in sherry-type wine. At low concentrations it’s a little bit nutty, which I amost always find in botrytized wines and at higher concentrations it is reminiscent of fenugreek. You find it in molasses, soy sauce, and those sorts of things – a vaguely caramel/salty/nutty aroma that’s hard to pin down exactly, maybe even slightly metallic somehow. It shows more strongly as the wine gets older. I suppose if one wanted to be trendy, one might even call it a kind of umami. There are also compounds found in honey that are produced specifically by the botrytis.
Another thing that happens is many of the original aromatic compounds in the grape are destroyed. Interestingly, the sulfur compounds that give Riesling a characteristic aroma seem to be tougher than the floral compounds in Muscats, etc. As a result, with botrytis, Muscat becomes more different than Riesling, although both are significantly altered.
There are compounds produced specifically by the botrytis that destroy phenols and anthocyanins. For example, there’s one, I can’t remember the name off the top but it’s related to or found in milk, and it’s why you lose color if you make botrytized wine from red grapes – at best you end up with a pretty salmon color, but you don’t get red. It’s an oxidizing agent too, and sulfur dioxide doesn’t affect it all that much, so you can end up with slightly oxidized notes even on a wine that’s been made in a reductive environment. In white wine it helps produce the amber color that you get when you age botrytized wine. I remember sitting with some people tasting through a few dozen botrytized wines and one person pointed out that the wine had a milky aroma. We thought it was strange, but after I learned what was going on, it made a bit more sense.
I don’t remember the specific numbers and don’t feel like looking them up right now, but if you take a botrytized grape and compare it to it’s unbotrytized sister, the total acidity may not be all that different but the make up will be. The uninfected grape has 2 – 3 times the tartaric acid, while the infected grape has about twice the malic acid. Malic acid of course is more severe on the palate and I think it’s what people are experiencing when they talk about “minerality”, so it’s good to have some sugar to offset it.
As the botrytis destroys the pectin in the grape and juice, that combines with calcium and you frequently get a precipitate in the wine. While that isn’t harmful, it does change the quality of the remaining liquid.
On top of all that, it’s way too simplistic to imagine that we have one grape w/out botrytis and one grape with botrytis. When you get botrytis, you get other things too. You can get other molds – penicillin, for example, and you get bacteria, notably acetobacter, which is important in creating vinegar, so sometimes you get a sour note and I think that’s the apricot quality some people describe. However, the presence of other fungi will certainly contribute to the “wooly” or musty flavors, and in seasons with a lot of rain, those flavors will be more pronounced.
All of those things happen in botrytized wine as opposed to things like icewine or wines where the grapes are dried, and those changes are why other sweet wines lack the complexity of botrytized wine.
Now to the taste of botrytis itself. As always, much depends on what one is used to. Grapes like Riesling, Semillon, and Chenin Blanc are what people know if they drink German and French botrytized wine. In my case, I’ve had much more Furmint, Hárslevelű and Muscat for example. However, there is a major difference in the wines made in Tokaj and those made elsewhere. In France and Germany, the juice is pressed out of the grapes and there is very little skin contact. They do this in Tokaj of course, for some wines. But when they make the aszú wines, they mash up the berries and macerate that in the must or wine. So unlike botrytized wines produced elsewhere, those particular wines have significant skin contact and consequently, significant mold contact. I think that’s a major reason many people don’t taste the botrytis – it’s not as present in the wines they’ve had although the effects of it are.
Keep in mind also that in Sauternes for example, they pick the grapes with a certain amount of liquid remaining. If the grapes are picked when truly desiccated like raisins, the flavors are far more concentrated within the grape and the ratio of mold to grape itself is higher. But you don’t have any juice. If you eat those wines from the vine, you get flavors very much like raisins, with a vague musty but not unpleasant quality. That’s one way to get a feel for what botrytis does. Another is to try botrytized wine that isn’t sweet but is fermented dry. Since you’re not distracted by the sugar, you can pay more attention to the botrytis effect. And of course the best way is to drink a lot of botrytized wine!
Cheers.
EtOAc.
Greg - Thank you very much for your post. I’ve read it, will re-read it, and will print it out for future reference. ![[cheers.gif]](/uploads/db3686/original/2X/0/0ff9bfcdb0964982cd3240b6159868fbdf215b1a.gif "cheers"){kind=small}