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:
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.
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.
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.
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!
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