fruit flies over ripe fruit.

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Handy Andy

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Good morning

My friend bought a property with vineyards, and left them to ripen, then rang me to say he did not have the time to pick them and make them into wine. 2 weeks ago these grapes would have been all good. I took approx 100kg of grapes letting a lot more go to the ground, covered in fruit flies. I crushed and sulphated and covered the remaining last night. This morning I took the cover off and a couple of dozen fruit flies escaped. I did not see any flies in there last night.

Do I have a problem, with this batch of grapes ?

Am I wasting my time trying to make wine out of this batch?

Could sulphate at the end of fermentation cure any problem ?

At what point should I tell people to keep their grapes?

Edit I found this link Dealing with damaged fruit in the winery which answers some questions. More than 5g/100l at the crusher, this I have done.

The grapes are now fermenting, but I suspect there must have been some eggs on the grapes prior to crushing because I saw another couple of flies come out of the barrel. I will add nutrients tomorrow, as suggested in the link.
 
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JohnT

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Fruit flies are known carriers of acetobacter, but it is still worth a try. I would give a heafty dose of k-meta at crush, then wait 24 hours before pitching your yeast.
 

Handy Andy

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I dosed 20mg 4 teas spoons of k-meta on a approx 100kg of grapes after I crushed, waited overnight then added yeast, today I added some nutrients. The fermentation appears to be going ok, and fruit flies stopped appearing.

How fast does acetobacter turn wine to vinegar? Can I expect the wine to get progressively worse as the week goes on? Or might the k-meta have prevented any problems?
 

balatonwine

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I crushed and sulphated and covered the remaining last night. This morning I took the cover off and a couple of dozen fruit flies escaped. I did not see any flies in there last night.

... snip...

The grapes are now fermenting, but I suspect there must have been some eggs on the grapes prior to crushing because I saw another couple of flies come out of the barrel.
It takes 10 days for fruit flies to go from eggs to adults. They will not appear from eggs overnight. More likely, there were adults in the must that crawled out over night, dried off and flew out the next day.
 

Handy Andy

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The amount of k-meta you need will be pH dependent. What you added may, or may not be sufficient. If the grapes were over ripe, maybe not. What was your must pH and total must volume after crush?
I didnt take the ph of the must before it started fermenting. The total volume of must is approx 150 litres. Just measured the ph at 2.9

Should I add more k-meta stop and restart the fermentation?

Only some of the grapes were over ripe, the ph would indicate the others could have used another week or two on the vines.

Edit found this What is Acidity in Wine? | Wine Enthusiast I might need to do a malolactic fermentation. acid 2.9 is a bit close to vinagre,
 
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balatonwine

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I didnt take the ph of the must before it started fermenting. The total volume of must is approx 150 litres. Just measured the ph at 2.9
Once fermentation starts, the chemistry changes. Dissolved CO2 in the must can decrease pH. A pH at crush of 2.9 is quite low, and would indicate under ripe grapes. But now, during fermentation, it is hard to say what may be the cause of the pH. To get an idea of ppm SO2 in your must you need to now switch to chemical analysis.
 

Handy Andy

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Once fermentation starts, the chemistry changes. Dissolved CO2 in the must can decrease pH. A pH at crush of 2.9 is quite low, and would indicate under ripe grapes. But now, during fermentation, it is hard to say what may be the cause of the pH. To get an idea of ppm SO2 in your must you need to now switch to chemical analysis.
Thanks Again for the advice. Sadly i dont think there are any chemical analysis facilities on this island. I guess now my only option is to finish the fermentation and try the wine, in about a weeks time.
 

Ajmassa

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3 days in and fermentation is bubbling away, I think normally! Must tastes, ok. No flies in sight. I might have gotten lucky. I will be pressing the wine on Saturday all being well, I will report then.
beautiful. I wouldn’t worry about anything other than a healthy successful ferment right now. You can re-evaluate your approach once dry & pressed when you can get accurate readings.

Wine is resilient and normally some fruit flies are no match for high abv, natural acids, and so2. Always exceptions but no need not to be optimistic.

(reminder- fresh after fermentation it’s overloaded with co2 and that skews ph readings. So shake the hell out of the sample a bunch of times. something I almost always forget to do)
 

balatonwine

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Sadly i dont think there are any chemical analysis facilities on this island.
Do consider ordering a simple home test kit of SO2. They are usually simple titration kits that can be ordered online and shipped to you and often cost less than $20 (USD). And a wine making supply company in Portugal should be able to ship to the Azores. These kits are very useful for later SO2 adjustment.
 

Handy Andy

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Pressed the wine seems ok. ph 3.95 sg 0.998, tastes ok. More importantly the misses says its ok too. I may have got away with having a few fruit flies in the must .

Thanks all for the input.

I now have 100 litres of vino novo. I treated it with 1 teaspoon of k-meta, closed the lid with water trap in place. I will check again in 3 weeks, then invite our friends around for a tasting.
 
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