Grape Wine Fermentation Process

Caring for Young Grape Vines

My name is David Handley, I'm with the Universityof Maine Cooperative Extension, and we're here to talk about how to prune and traina young grapevine. This is a vine that was planted last spring. We got it from a dormantplant, or rooted cutting, and you can see the original part of the planting right here.This is what we got from the nursery, with a good root system under it. We planted it,and we had a bud break and some vine growth. This is last year's growth right here. Thiswas a green shoot. Typically, you may get more than one shoot developing. You may haveseveral buds on here. We want to prune this back to one strong vine, your strongest one.We're going to arrange for that to be tied

up to a trellis, because this particular vineis what's going to become our permanent trunk, or the permanent part of the plant that'sgoing to be with us for the life of the planting. We want to make sure it's the strongest ofthe vines that we can choose from. Any other one that developed that's very weak, we canjust cut that out, select our best one. The time of year to make these cuts are whenthe canes are dormant, and this is going to be really any time after the new year, untilthey bud out in late March, early April. We hope in the first year that we get enoughgood growth that we can tie it to the lower trellis wire.Typically here in Maine, we're going to be

pruning to either a four arm kniffin trainingsystem, or an umbrella kniffin training system. Those trellises consist of two wires, oneset at about two and a half feet, and a second wire set at about five feet.We hope in the first year that we're going to get enough good growth to reach at leastthe bottom wire, but in order to make sure it's growing straight, you can see we supportedthis with a small bamboo pole. Any kind of planting stake will work, and we just tiethat vine up as it grows, rather than let it grow along the ground where it can getrot problems, and not develop a nice straight growth like we want. We tie it up, just likeyou'd tie up a beef steak tomato, get the

growth that you want.As I said, we've got pretty good buds here, reaching up to the first wire. You can seethat I actually make it to the top wire, but you can see the growth up here is very scrawnyand spindly, and isn't really going to lead to a good, strong trunk. I'd rather actuallystart new growth for reaching to this top wire for next year.What that means is that I'm actually going to cut this off here, rather low, to try toget this bud here to break and give me a much stronger shoot to develop my trunk to thetop wire next year. I can just take that there, and then, instead of using the bamboo polethis year, I can just tie it to the wire.

This bud will hopefully break, and give mea good, strong shoot, that I'm going to reach the second wire next year. Of course, thesebuds lower down will also break, and if this one happens to be weak, I may select one ofthese. But, if this bud does turn out to be a strong shoot, I'll be cutting these offnext winter and getting my single trunk back up to the top wire.Next year, when this does reach the top wire, eventually what we'll be doing is taking oneyear old cane, and either draping it over this top wire and connecting it to the bottomwire in an umbrella kniffin, or we'll be taking one cane at the top wire on each side, andone cane at the bottom wire on each side,

to create four arms of one year old growth,for a four\uc0\u8209 arm kniffin system. Both systems work pretty well for concretetype grapes here in a cold climate like Maine.

Making The Perfect Wine

Wine. about 32 billion bottles are bought and sold around the world each year each bottle contains about two and ahalf pounds of grapes but before you get here the process starts here where winemakers worktowards creating the perfect blend of aroma, color and taste. I would say the trickiest part of making wine is getting the flavors right A big part in getting that right is notonly the grapes

but the fermentation of those grapes.Right now or in the UC Davis research winery and we are looking at the fermentation tanksthese are our production fermentation tanks inside these tanks the yeast converts the sugar in grapes into alcohol. So here we have our hightech monitoring system for all these tanks, you can see here you can select individual tank, you can see the volume of the tank the temperature of the tank. Biochemists monitor the yeast as they battle what seems to be a

microbial war Yeast are these incredible microbialjuggernauts they are they suck up all the nutrients they suckup all the oxygen they're incredibly dominant fermentation and on top of thatthey make alcohol so there knocking back the growth everybody they can just cycle and grow very very quickly get a fermentation going and finish afermentation very quickly If all goes well fermentation can becomplete in two to three weeks but sometimes the yeast lose thebattle. As a winemaker

that's not great cause really what you want yeast to do is just get in there kick butt and finish the fermentation. A problem that has plagued the wineindustry for centuries is when fermentation stops. So one ofthe big problems with the industry is stuck fermentation or an arrestedfermentation where sugar is left behind Now for the first time yeast geneticist Linda Bisson and her team have discovered what triggers stuckfermentation.

Researchers learned that an abnormalprotein is created in yeast by bacteria in the wine these proteins can reproduce themselves inside of the yeast causing the yeast to slow down or stop converting sugar into alcohol when the yeast stop working they become stressed and give off a sulfur smell like rotten eggs, clams and badvegetables excess sugar is left behind and the wine becomes too sweet So we think what the yeast are doing is they're taking that signal from the

bacteria and slowing their metabolism downslightly slowing down their uptake amino acids slowing down their uptake of oxygen and slowing the fermented processes a little bit. Now that they know what's causing it,researchers are working to create yeast strains that will ignore thebacteria, not make the protein and keep on working. The industry simply wants the problem solved, they don't wanna have bad sectors

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