Sweet Wine Course #3 – Microclimat & harvest

Video transcription:

« Hello, today I’m going to tell you about the Sweet Bordeaux microclimate and also about harvesting. So first of all, there are several ways of making sweet white wines. For the Sweet Bordeaux they are wines made from “the noble rot”. For this, you need a very specific microclimate, humidity alternating with dry and ventilated hot weather that will allow a progressive development of that fungus that is called Botrytis cinerea that is a microscopic, magic fungus and that allows for a natural concentration of sugar in the grape. Particularly, how does it work in the vineyard? Well, in the morning we have that fog because there are rivers and even a difference in temperature between the cold waters of the Ciron, which is a small river, and the Garonne and it creates the condensation phenomenon. So, the vineyard is covered in fog and of course, like any fungus the Botrytis will develop. Then by late morning, the sun will clear that fog will diffuse its heat. And so, will stop the fungus. So, how does the Botrytis cinerea, that famous “noble rot” work particularly only on the grape? The thick skin of the Sémillon will allow the fungus to settle without altering the look. Then, the fungus will anyway end up damaging the grape’s skin making it waterproof, puncture it, so the water will evaporate which is also encouraged by the hot air if there is a hot, dry wind for example and then we’ll get a concentration of sugar in the grape, the sugar concentration will even double in the grape. Physically, we can really also see a difference on those grapes. First it will become brown then it will start softening then following the water evaporation we’ll see wrinkled and then dried up grapes. Let me also say what is also very interesting with noble rot with that fungus, is that it will synthesize a molecule which makes those candied aromas that characterize those wines. So now, regarding the harvesting, it is a manual harvest because we’ll only pick grapes that are, what we call, roasted rot that is to say in the last stage of Botrytisation so very dry, concentrated grapes. And so as it is a heterogeneous phenomenon all the grapes won’t be stricken with roasted rot at the same time so we’ll have to go several times through the vine to only pick those roasted rot grapes that are really ready. That is what we call successive sorting on an average there are 3 to 6 sortings. So we have harvests which also take a bit longer because of those sortings. The harvest starts early October and can last 1 month or even 1 and a half month and in extreme cases it can stretch until December. It is a small production because of the water evaporation so instead of usually having a vine per bottle, for the Sweet Bordeaux we have one vine for 1 or 2 glasses. See you very soon for another episode. »