Category Archives: enology

Pressing Merlot

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When to press red wine

When making red wine from grapes, you crush the grapes then ferment them. You leave the skins and pulp in the fermenting wine, for a time, then you press it and leave the solids behind. The amount of time will vary according to the style of wine you’re making. Three or four days, will yield a light bodied wine. A few weeks will yield a tannic, full bodied wine. A good full bodied wine requires top notch fruit, and since I don’t have detailed information on how my grapes were grown I decided to make a medium bodied wine, and pressed after a week.


Pressing Merlot in a bladder press on 10/20/07


Here you can see the bladder press I used to press my Merlot.

Using a bladder press

I loaded the fermenting wine, pulp skins and all, into a perforated cylinder. At first, “free run wine” flowed out of the perforations, leaving seeds, pulp and other debris behind. Later, I applied water pressure to inflate a rubber bladder that squeezed the grapes against the sides of the cylinder and “press wine” flowed out. Altogether, I got over eight gallons (30+ liters), which is more than I expected from my 100 lb (45+ kg) of grapes. I was going by the rule of thumb that 100 lb would yield 5 gallons (about 19 liters).


Pressed Merlot in 5-gallon carboys, press wine in the carboy with the orange handle and free run in the carboy on the right. 10/20/07


I kept the free run and press wine separate. The carboy on the left, with the orange handle, contains press wine, while the carboy on the right contains free run. It’s still fermenting, and I expect it to finish in another week. Once it starts to clear, I’ll rack into fresh containers for aging. At that point, I’ll have to decide if I want to keep the press and free run separate or combine them.



Merlot: Punching Down The Cap

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When making red wine from grapes, you will be fermenting crushed fruit. So the skins, seeds, pulp, probably some stems and other debris are all mixed into your fermenting wine. When the yeast are active, all the carbon dioxide (CO2) they produce is rising to the surface pushing those solids up with it. They collect on the surface, forming a cap. The whole point of putting grape skins in your must is to extract beneficial compounds from them, and this can’t happen while they’re out of contact with the fermenting wine. Also, yeast have no access to these solids and can’t crowd out other microorganisms, leaving the cap open to infection.


Using a long handled spoon to punch down the cap of this fermenting Merlot wine on 10/17/07


You can see the solution in the above photo, where I’m physically submerging these solids with a long handled spoon. I keep doing this until all the solids have been pushed down into the fermenting wine. “Punch down the cap” like this twice a day, while the yeast are active, and you should have no problems with extraction or infection.



Making Wine From Purchased Grapes

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Grapes in the crusher and burgers on the grill

The grapes I ordered arrived on Sunday (10/14/07). I brought home a 24-gallon fermenter with 100 lb (45.4 kg) of crushed Merlot grapes and two 5-gallon (19 liter) carboys, each with about three gallons (11+ liters) of Chardonnay juice. The boxed grapes arrived in a truck, and I participated in crushing and pressing them.


Processing Chardonnay grapes in a manual crusher on 10/14/07


I rolled up my sleeves (note to self, next time wear a short sleeved shirt) and got my hands sticky. I switched out catch buckets, scooped crushed grapes out of the crusher, loaded the press, hand cranked the crusher, and poured juice into the carboys – it was exhilarating! I didn’t have to do all that. They were well staffed and would have crushed, scooped, pressed, and poured for me. I like making wine. If I wanted to pay someone else to do it, I could just go to the store and buy some very nice wine. I wasn’t really all that tired after all that, but I was hungry. So I really appreciated the hamburgers and hot dogs they were grilling up on site. It was a nice lunch that turned the whole thing into an event.

Measuring sugar and acid

After I got the crushed Merlot grapes and the Chardonnay juice home, it was time for measurements. For that, I needed a clear sample. I lowered a clean ladle into the Merlot grapes, so that juice slowly flowed into it over the edges. After a few times, I had about a cup (240 ml), which I let settle for an hour. The Chardonnay was in two carboys, free run juice in one and pressed juice in the other. I drew samples, about a cup, from both with a wine thief and let them settle along with the merlot. This is when I added the pectic enzyme.

Settling for an hour isn’t going to produce perfectly clear juice, but a lot of sediment did fall to the bottom and the juice I poured off was a lot clearer than the what I started with. I think the Merlot and the pressed Chardonnay juice were clear enough to get good measurements from. The free-run Chardonnay was too cloudy, even after settling, so I didn’t use that sample.

There Merlot, as I measured it, was at 25 Brix, pH = 3.63, TA = 7 g/L
The grower reported 24 Brix, pH = 3.56, TA = 5.1 g/L

For the Chardonnay, I got 26 Brix, pH = 3.15, TA = 11 g/L
That compares with the grower’s 24.7 Brix, pH = 3.27, TA = 7.7 g/L

In both cases, I saw slightly more sugar than the grower. I think this is because my samples still had a lot of suspended solids in them and that the actual amount of sugar is probably a little less than what the grower reported. I measured higher pH and higher TA in the Merlot. That may mean a higher proportion of malic acid and therefore slightly under ripe grapes. I recorded a higher TA for the Chardonnay too, but my pH reading was lower. So my juice was more acidic, but there was no divergence as there was with the Merlot.

Pitching the yeast

There was nothing in those measurements that bothered me, so after giving the pectic enzyme three hours to do it’s work I pitched the yeast. I used Red Star’s Premier Cuvee, a neutral reliable yeast. I prepared a starter on Friday (10/12/07) by reconsituting a can of frozen grape concentrate. I could have just used sugar and water, as I described in August. By Sunday afternoon, I had 1.5 quarts (1.4 liters) of fermenting grape juice. I gave it a good shake and added about two cups to the Merlot and one cup to each carboy of Chardonnay.

Those yeast were fermenting up a storm the next day. After they do their work, it’ll be time to rack the Chardonnay and press the Merlot. That will mean a trip back to the homebrew shop, to use their press, in about a week.

Hot Pressing In A Cool Climate

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Great news for fungi, bad news for grapes

The cool climate, here in the Puget Sound Region, keeps growers on the edge. We want to grow noble varieties like Pinot Noir and Chardonnay, which will ripen here but just barely. We also want reliable grapes that ripen even in bad years like this one. Grapes like Madeleine Angevine and Seigerrebe shrugged off the cold wet season and delivered good, if somewhat smaller, crops. A lot of Pinot Noir and Chardonnay is still braving the wet weather, and the fungal diseases that thrive in it, to ripen. Some wont be harvested at all, and many will be harvested with the beginnings of botrytis.

Heat the grapes to repair some of the damage

How do you salvage barley ripe grapes beset by bunch rot? Thermovinification, or “hot pressing,” is the process of heating red wine grapes to kill spoilage organisms, improve color, and reduce unripe flavors. Heating to 150F (65C) for 20 minutes, 180F (90C) for 2 minutes, will do the trick. At this point you can cool the must and ferment normally or press the grapes and ferment like a white wine. It’s best not to leave under ripe grape skins in contact with the fermenting wine for very long.

Adjust the acidity

If you had to harvest before your grapes are ripe, you will have to deal with their acid profile. It isn’t just a matter of reducing high acid levels with something like potassium bicarbonate (KHCO3), the mix of acids may be unfavorable. As grapes ripen, the amount of malic acid falls, while tartaric acid rises. So in under ripe grapes, there will be a disproportionately more malic. That’s when a yeast like Lavlin’s 71B, which consumes malic acid, can come in handy. If, after fermentation, there is still too much acid, then it’s time for the KHCO3.

These steps can make the difference between a lost cause and a drinkable wine, but they won’t conjure up a fine wine from mediocre grapes. Do your best, look forward to next year, and sip some heat treated wine 🙂

Further reading

In his 10/3/2003 Letter to NY winemakers, Thomas Henick-Kling writes about making wine after a difficult harvest. My thanks to Gerard Bentryn of Bainbridge Island Vineyards for recommending that paper.

Jancis Robinson has a great entry on thermovinification in her The Oxford Companion to Wine.

Raspberry Wine Recipe

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I made raspberry wine last year. I haven’t talked about it before because I made it and racked it before I started blogging. I also made it before I owned a pH meter or an acid test kit, so I was really flying blind. How do you make raspberry wine without measuring the acidity? I measured what I could, then I consulted Ben Rotter’s table of fruit data. It’s a goldmine of data about sugar, acid, and tannins in fruit as well as juice yield.

Raspberry Wine Recipe

My 10.75 lb (4.9 kg) of raspberries yielded 3 quarts (2.8 liters) of SG 1.050 juice. My notes show that I expected a TA of 14-18 g/L, though when I look at the table now that seems low. I picked the fruit at a U-pick farm after some unusually hot weather. My notes don’t say, but maybe I was expecting the hot weather to lower the acid. At any rate, I dissolved 3 lb (1.4 kg) sugar in 3.3 quarts (3.1 liters) of water. I treated with sulfite, pectic enzyme, and nutrient then pitched the yeast. It fermented to dryness in less than two weeks.

More on raspberry wine

Promising, but too acidic

I did some measurements recently:

SG = 0.992
TA = 14 g/L
pH = 2.96
volume = 1.5 gallons (5.7 liters)

It tasted tart, but it wasn’t the undrinkable firewater you might expect. There was a very nice flavor in there, and it complemented the raspberry aroma very well. I decided to use potassium bicarbonate (KHCO3), to take down the acid a notch, at a 1.5 tsp/Gallon (2.4 g/L) rate. I’m hoping to reduce the acid by 2-3 g/L. I’ve set it aside, with the cherry wine, and intend to taste them both in a few months. Maybe that’s all the raspberry wine needs, or maybe the acidity will still be too much. If so, it’ll be time to sweeten it a little.

Do as I say, not as I do!

I think this is going to have a happy ending, but you really should do your own measurements. Bookmark Ben’s site, and not just for the fruit data, and use it to help make your own recipes, but make final decisions about acid and fruit proportions based on accurate measurements of the fruit you are using.

Update 12/9/2008 – It needed sweetening

It’s still too tart, even after neutralizing some of the acid, so I sweetened my raspberry wine.

Why I Make Dry Wine

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I make wine out of many different fruits and vegetables – from raspberries to rhubarb and all sorts of things in between. That makes for a lot of trial and error as I learn how to consistently make a good wine using very different bases. Many traditional country wine recipes call for a small amount of fruit, a lot of water, enough sugar for 12% alcohol, and acid to balance. You can make (and I have made) good wine this way, and it’s a real money saver. Still, adding a lot of water bothers me and some of the wines I’ve made this way seemed to suffer for it.

That made me wonder what would happen if I used more fruit. What about all fruit and no water? I’m trying this with cherry wine right now, and the first problem I had was in managing the acids. The titratable acidity (TA) of my cherry wine will be high, and that’s something I’ll need to address the next time I make it. I’m working on some ideas, but in the meantime I’ve decided to sweeten the cherry wine. I’ll be trying to balance the acid with sugar and make a drinkable wine out of it.

Learning to make good sweet wine by making good dry wine

I wrote about how to rescue bad wine with sugar on Monday, and the reason this works is also the reason I usually make my wines dry. That might seem strange; if sugar can save bad wines, why can’t it improve any wine? Used correctly, it probably can. Sweet things taste good to all of us, that’s just human physiology. But sugar can mask faults in a wine, and that’s why I stay away from it while I’m learning and experimenting. I need to be able to see the problems in order to fix them. When I understand what I’m doing with a particular wine well enough to make a good one consistently, then I’ll think about making a sweet or off-dry wine.

Restarting a stuck fermentation

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Don’t panic!

It happens. Sometimes, after a promising start full of froth and vigor, the yeast tap out and leave a partially fermented must/wine. It’s not drinkable and you certainly shouldn’t bottle it, but it’s also vulnerable to spoilage. So how do you get the yeast going again? I’ll explain how I do it, and use my oregano wine as an example.

Find out, and correct, the problem

It’s not always apparent what went wrong, but it’s worth the effort to try and find out. If there is some underlying problem that is inhibiting the yeast, then just adding more yeast, even a vigorous starter, won’t help. This is where good measurements and careful note-taking pay off. Nobody ever plans for things to go wrong, and that’s why good habits should become habits. My oregano wine suffered from a pH problem, and that brought fermentation to a halt. I suspected the pH after reviewing my notes, and confirmed it with a measurement.

Other potential problems that you might consider are temperature, preservative in store bought juice, nutrient deficiency, or lack of oxygen. Review your notes, take measurements, and do your best to discover why your yeast stuck.

The yeast began fermenting again, albeit very slowly, after I corrected the problem. It probably would have fermented out, eventually, if I had left it alone. A long slow fermentation like that is risky, however, so I decided to treat it as though it were stuck and hurry things up a bit.

Gradually add the stuck wine to a vigorous starter

After fixing the underlying problem, you should make a starter. This builds up a large population of actively growing yeast. Add some of the stuck wine to the starter. I like to double the volume every four hours or so, and since my starter was about a cup, I added a cup of wine to it. Four hours later: two more cups. Four hours after that would have been well into the wee hours, so with about a quart (close to a liter) of fermenting wine, I went to bed. In the morning I added another quart.

Nutrient: Not too much, not too little

Without enough nutrient, the new yeast may have trouble growing and fermenting the wine. If there’s more than the yeast can consume, some nutrient will remain in the fermented wine. That can cause off flavors all by itself, and it can also support spoilage organisms. So there’s no way I can tell you how much, if any, nutrient to add at this stage. The best way to decide is to measure the available nitrogen in the must, but it’s pretty unusual for home wine makers to run such an involved test.

If you haven’t got a chemist and a state of the art lab handy, gather up all the information you have about how much nutrient was in the must, how much you added, and how much yeast activity there was. Did I mention the part about good notes? If you started with a lot of nutrient and the yeast didn’t get very far, then you shouldn’t add much (or any) nutrient. If, for whatever reason, you’re starting nutrient level was low then you should add some. I realize that “a lot”, “much”, “low”, and “some” are a little vague, but the only way to get precise answers is with that chemist and the state of the art lab that we haven’t got.

My Oregano Wine recipe called for 1 tsp/Gallon of diammonium phosphate, which isn’t a lot. Since the must was basically a sugared oregano tea, it had virtually no nutrient except for what I added. So I decided to add another tsp of DAP along with the yeast starter.

I’d like to say that you won’t have to deal with stuck fermentations, but if you make wine regularly you’ll probably have to face an unmoving hydrometer sooner or later. Your best bet is to start dealing with it before it happens with good procedures and meticulous note taking. If you do that and use your head, you’ll have a good shot at saving your wine.

Oregano Wine Recipe: First racking – at last!

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Oregano Wine after racking on 9/3/07


I’ve never been happier with a specific gravity measurement than this one: 0.993 on 8/31/07. After the pH crash and the stuck fermentation, after the potassium bicarbonate addition and the yeast starter, and after all that waiting my Oregano Wine has finally fermented out! I racked on 9/3/07 to a 1-gallon jug and a half-bottle. I poured the thick slurry that was left into a beer bottle to settle. I’m a little worried about oxidation because I’ve kept the wine in it’s primary fermenter since June, but there is no sign yet and I’ve treated with sulfite.

Produce Department Chablis

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Welch’s wine? While you’re at the grocery store, head over to the freezer section for some frozen grape juice concentrate. Then try my Welch’s wine recipe and see how it compares.I’ve always wanted to make wine from grocery store grapes. It’s not that I’m expecting greatness, but that I’m really curious. Grapes were on sale for $0.88/lb. One variety was Thomson Seedless, the others were just called “red” and “black”. They were all seedless, and they all tasted the same to me. I ended up buying roughly equal amounts of all three, 20.34 lb total, to make wine with. Here’s how I did it:

Ingredients

About 20 lb (9.2 kg) of seedless table grapes
1 tsp pectic enzyme (approximately 2.3 g)
sulfite to 50 ppm (equivalent to 1.5 campden tablets)
sugar to SG 1.090 (about 0.375 lb or 170 grams in my case)
Premier Cuvee yeast

Sort and destem, then extract the juice

After discarding the moldy ones and destemming the rest by hand, I had 19.4 lb (8.835 kg) of grapes.

Red, green, and black seedless grapes half-filling their own 2-gallon buckets

There’s more than one way to juice grapes. I’ve used grape crushers and bladder presses when I bought wine grapes. I’ve crushed cherries with my feet when I made cherry wine. I’ve even built a simple press out of three plastic buckets. This time I ran my grapes through a juicer that I’ve been meaning to try.

Juicing the grapes with a Juiceman 210

It worked pretty well, though I did have to stop and clean the filter screen a few times. I ended up with about 5.44 quarts (5.15 liters) of juice which works out to one gallon from 14.25 lb of fruit (one liter from 1.7 kg). That is almost exactly what I got from Riesling grapes when I used a crusher and bladder press (one gallon from 14.29 lb of fruit).

Measure the sugar and acid

Up to this point, I kept each batch of grapes and their juice, separate. I was curious if I’d notice a difference in flavor or yield. I also wondered how much color the red and black juice would have. Well the yield was nearly identical and they tasted the same to me, but the red and black grapes did yield colored juice. This may end up as a blush or rose if that color persists in the finished wine. It would have been a little tedious to ferment them as three separate batches, so I combined them and added the sulfite and pectic enzyme. Next, I needed to measure the sugar and acidity, to know what adjustments to make.

Red, green, and black grape juice each half filling a 1-gallon jug

It was easy enough to draw a sample and measure the acidity. The pH was 3.35 and the TA was 7 g/L, as tartaric. Dry white wine musts are normally 7 – 9 g/L TA and 3.1 – 3.4 pH, so no need to adjust the acidity.

The suspended solids in the juice were going to make it difficult to measure the sugar. To get an idea of how much sugar there is, I measure the specific gravity with a hydrometer. Suspended solids in the juice will raise the SG, making it look like the sugar content is higher than it really is. So I decided to let the must sit overnight. This would let the pectic enzyme do it’s work and allow many of the solids to settle out. With luck, I could get a clear sample and get a meaningful SG reading.

I always worry about my must when I have to let it sit for any length of time. Yes, the sulfite will protect it, but I’d feel better if the yeast were busy. Having them dominate a must, and ferment to dryness quickly, is a great defense against spoilage organisms. So I decided to make a starter. I didn’t follow my own careful instructions, here, rather I just added the rehydrated yeast to 0.5 cups (120 ml) of must and let it go overnight.

Measure and adjust the sugar

By morning, the starter was happily bubbling and I checked in on the must. It’s not as though all the solids dropped to the bottom and I had a gallon of crystal clear juice to sample, but with some care I was able to coax 0.5 cups of clear pink juice into my test jar. The SG was about 1.078, and I’m aiming for 1.090. So I need to add sugar. How much? The short answer is that 0.375 lb (170 grams) of sugar dissolved in just under 0.5 cups (100 ml) of water (boil and cool the sugar water to keep out the nasties) will bring the SG up to 1.090. You can use this formula to calculate how much sugar water (2 parts sugar, by volume, and 1 part water) to add to your own must:

x = ( V * (TG – SG) ) / (1.310 – TG)

where x is the amount of sugar water, in liters, to add
V is the volume of must, in liters (5.15, in my case)
TG is your specific gravity target (1.090)
SG is the current specific gravity of your must (1.078)

If you’re wondering where the 1.310 came from, it’s the specific gravity of sugar water. So make sure you use 2 parts sugar (by volume) to 1 part water or the above formula won’t work. In my case x was equal to 0.281 liters. To make the math and the measurements easier, I rounded that to 300 ml. That means I needed 200 ml of sugar, which weighs about 170 g, dissolved in 100 ml of water.

I added the sugar, pitched the starter, and noticed vigorous fermentation in hours. Wine from produce-section grapes! Who knows how it will taste, but pretty cool, huh?

Update 7/27/2009 – Sugar additions the easy way!

If you’re put off by the math I used to adjust the sugar, check out my new Wine Recipe Wizard. I wanted to make sugar and acid adjustments easier by just having you type in the volume of juice you have, your hydrometer reading, and (optionally) your titratable acidity. Then just type in what you want the sugar and acid to be and the wizard will tell you what to add. I hope this helps – let me know if you have trouble using it.

Update 11/15/2009 – Disappointing

I don’t think I ever had high expectations for this wine. I never imagined comparing it to an aged Premier Cru Chablis, but I was hoping for a nice table wine. I didn’t get that. The wine is balanced, there are no faults, but there is no flavor either. I’m starting to think about how to improve the procedure, but until that stroke of genius hits, I had to say that wine from grocery store grapes is bland.

Update 12/3/2009 – Save it by making mulled wine?

When produce department grapes give you something bland, make mulled wine! I’m hoping that traditional mulling spices like cinnamon and clove along with citrus zest will add some life to this wine. This will be my first time making mulled wine, so I’m excited!

Easy To Make Wine From Grocery Store Grapes

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Why make wine from table grapes?

Grapes from the produce section of the grocery store are meant to be eaten fresh, and you shouldn’t expect them to make top notch wines from them. Still, I’ve always been curious about what sort of wine they would make. The green seedless grapes that are so common are called Thomson Seedless. A local grocery put Thomson seedless and two other seedless grapes, identified only as “red” and “black,” on sale for $0.88/lb. Here was my chance to satisfy my curiosity and get a good deal. How could I pass that up?

How do you make wine from table grapes?

These grapes, Thomson Seedless and other two, are large compared to most wine grapes. Which means that, pound for pound, they have much less skin than wine grapes. I could go into the geometry, but I’ve been sipping some of my wine tonight and trying to commit mathematics right now could get really ugly. Trust me on this – large grapes means less skin. So these grapes wouldn’t be suitable for red wine, which gets it’s flavor and tannin from the skins. Also, some of these unidentified “red” and “black” grapes might be American or hybrid grapes, which may have a “foxiness” or other undesirable flavors to them. Making a white wine from them could help minimize or avoid these off flavors.

So it’s best to approach this sort of wine as a white (or blush or rose depending on how much color the “red” and “black” grapes contribute). I decided to buy about 20 lb (around 9 kg) of these grapes, roughly equal quantities of each, and juice them. After testing the sugar and acid, I would adjust the juice appropriately for a white wine. That means a titratable acidity of 7-9 g/L (it will drop during fermentation to about 5-7.5 g/L) and a pH of 3.1-3.4. It also means enough sugar for about 12% alcohol. I’m inclined to make a dry white, but these grapes might produce a bland wine. As the wine matures, I may decide to sweeten it if I think it needs a little help.

This should be an easy and fun wine to make, and I started making it today. I’ll explain how over the next day (or few days).