A seemingly failed green grape wine

[nagomi]

Ingredients:
500g of green grape (I don't know its exact name. it looks very much like this: indian green grape - Google Search)

1 cup of white sugar

What I did:
1) Take some hot water in a 1.8 liter glass jar and wait while boiling water
2) pour boiling water into it for disinfection.
3) while the glass jar is cooling down, crush the grapes in a bowl with bare hands
4) put the grapes and its resulting juice into the jar
5) add one cup of sugar
6) seal with a cling wrap and poke a hole in the middle with a pin

The end.

Two weeks later, the picture is what it is and smells a bit like soy sauce. Tastes a bit salty and the flavor is like baking soda. Oh no... I tasted it again to be sure and it's ghastly.

What did go wrong and where should I correct? I do know it would be nice to have lab cultured yeast and starsan and all, but have no access. This is all I have and are available thanks to the quarantine.

 

[bernardsmith]

Well, 500 g of grapes is about 1 lb and I would think you want about 5 lbs of grapes if you want to make a wine from store bought eating grapes. I won't say anything about their suitability in terms of taste, but they certainly do not have anything like the sugar content of wine grapes. But be that as it may. But if you were looking to capture and then harvest the indigenous yeast that might be on those grapes I think you may have gone about this the wrong way - You were close but no cigar, as they say.

Here's my take on this - and I have been experimenting, in the last couple of weeks, with indigenous yeast from grapes and from raisins and here's the thing
1. Not every fruit you buy or have will have wild yeast on it. Sometimes the warehouse is required to irradiate fruit especially when imported. But let's say that your grapes did have yeast on them
2. You want to grow the yeast - that is to say, to increase the number of yeast cells. When you buy a pack of yeast there are BILLIONS of potentially viable yeast cells in the pack, There may be a few thousand yeast cells in your grapes. So, I would take a handful and press them to crack their skins. I would pour about 500 ml of chlorine free water on them (I use spring water) and I would allow the grapes to sit submerged in the water for about three or four days. Two or three or more times a day I would shake the jar so that I was adding oxygen to the solution: yeast need oxygen to reproduce. You are NOT interested at this point in the yeast producing wine, You ARE interested in having the yeast reproduce. You will know when they are beginning to reproduce when you see bubbles rising from the bottom and you see the grapes begin to float towards the top.
Even if you don't see too much activity after about four days I would a) strain out the fruit and to the liquid I would add a tablespoon of sugar. AND I would add some nutrients for the yeast. In my experiments I crushed multi-vitamin tablets that I take - they contain the same vitamins and minerals as the yeast need. After a day or so - and you are still shaking the bejeebers out of the jar two or three or four times a day - you should see a lot more activity. At that point I would create a mix of sugar and water and nutrients: using about 1 lb (a scant half kilo) of sugar to a gallon (US) of water - or about 100g to a liter and I would add the liquid with the yeast. If you have an airlock I would attach that so that you could see if there is any real action happening.
I would - as you did - smell the liquid. It should not smell bad at all.

As I say, I have been experimenting with indigenous yeast and I was able to harvest a colony from some raisins I had (preservative free) and I used the colony I grew to ferment a heather wine. I was also able to harvest some yeast from a bunch of grapes that were beginning to go soft and squishy. Have not tried using that yeast yet but I am still feeding it and encouraging it to grow.
Anyway... my guess is that you will successfully grow and harvest one colony of yeast for each 4 attempts you make and you may find that for each successful colony you harvest you will have grown a strain that you like and for each strain that you like you will find that you will be able to encourage a very small number of cells to tolerate the acid level and levels of alcohol that you want in a wine. Indigenous yeast are not known for their tolerance to acids or alcohol so you need to help modify any culture you grow to tolerate the conditions you want them to thrive in and you do that by slowly increasing the amount of alcohol you ask them to live and work in - 2% ABV, 5% ABV, 7% ABV, 10% ABV, 12% ABV etc and the amount of acidity in that alcohol . This takes time.
Good luck.

 

[Seamonkey84]

On top of the use of wild yeast. Going based on a U.S cup (240mL), to that amount of grapes, that was way too much sugar. But without taking measurements, your really going at it blind. For doing this with store bought grapes. Try a pound of sugar to one gallon of store bought grape juice, or 10lbs of grapes. Then get or make a airlock. The first few days can be done In a bucket with a tight weave towel, but then you want to get it into a jug to keep the air out but let pressure escape. Even If you can find active dry bread yeast, that would be a sure bet compared to going wild. Otherwise, do as Bernardsmith mentioned to grow your own yeast first, then if it works, add it to more juice or grapes. It can be as simple as this

 

[nagomi]

Well, 500 g of grapes is about 1 lb and I would think you want about 5 lbs of grapes if you want to make a wine from store bought eating grapes. I won't say anything about their suitability in terms of taste, but they certainly do not have anything like the sugar content of wine grapes. But be that as it may. But if you were looking to capture and then harvest the indigenous yeast that might be on those grapes I think you may have gone about this the wrong way - You were close but no cigar, as they say.

Here's my take on this - and I have been experimenting, in the last couple of weeks, with indigenous yeast from grapes and from raisins and here's the thing
1. Not every fruit you buy or have will have wild yeast on it. Sometimes the warehouse is required to irradiate fruit especially when imported. But let's say that your grapes did have yeast on them
2. You want to grow the yeast - that is to say, to increase the number of yeast cells. When you buy a pack of yeast there are BILLIONS of potentially viable yeast cells in the pack, There may be a few thousand yeast cells in your grapes. So, I would take a handful and press them to crack their skins. I would pour about 500 ml of chlorine free water on them (I use spring water) and I would allow the grapes to sit submerged in the water for about three or four days. Two or three or more times a day I would shake the jar so that I was adding oxygen to the solution: yeast need oxygen to reproduce. You are NOT interested at this point in the yeast producing wine, You ARE interested in having the yeast reproduce. You will know when they are beginning to reproduce when you see bubbles rising from the bottom and you see the grapes begin to float towards the top.
Even if you don't see too much activity after about four days I would a) strain out the fruit and to the liquid I would add a tablespoon of sugar. AND I would add some nutrients for the yeast. In my experiments I crushed multi-vitamin tablets that I take - they contain the same vitamins and minerals as the yeast need. After a day or so - and you are still shaking the bejeebers out of the jar two or three or four times a day - you should see a lot more activity. At that point I would create a mix of sugar and water and nutrients: using about 1 lb (a scant half kilo) of sugar to a gallon (US) of water - or about 100g to a liter and I would add the liquid with the yeast. If you have an airlock I would attach that so that you could see if there is any real action happening.
I would - as you did - smell the liquid. It should not smell bad at all.

As I say, I have been experimenting with indigenous yeast and I was able to harvest a colony from some raisins I had (preservative free) and I used the colony I grew to ferment a heather wine. I was also able to harvest some yeast from a bunch of grapes that were beginning to go soft and squishy. Have not tried using that yeast yet but I am still feeding it and encouraging it to grow.
Anyway... my guess is that you will successfully grow and harvest one colony of yeast for each 4 attempts you make and you may find that for each successful colony you harvest you will have grown a strain that you like and for each strain that you like you will find that you will be able to encourage a very small number of cells to tolerate the acid level and levels of alcohol that you want in a wine. Indigenous yeast are not known for their tolerance to acids or alcohol so you need to help modify any culture you grow to tolerate the conditions you want them to thrive in and you do that by slowly increasing the amount of alcohol you ask them to live and work in - 2% ABV, 5% ABV, 7% ABV, 10% ABV, 12% ABV etc and the amount of acidity in that alcohol . This takes time.
Good luck.

Thank you so much for such a detailed and intricate response. I wasn't really expecting for the first a few days. Now I'm trying to cultivate my own batch of yeasts as you have suggested. My question is how do you tell apart the yeast that can hold higher ABV without any measuring device? I'm stuck here with practically no access to any kind of brewing-related stuff. Just a few fruits and sugar, wine and a bottle of dry active yeast for baking. That's it.

 

[nagomi]

On top of the use of wild yeast. Going based on a U.S cup (240mL), to that amount of grapes, that was way too much sugar. But without taking measurements, your really going at it blind. For doing this with store bought grapes. Try a pound of sugar to one gallon of store bought grape juice, or 10lbs of grapes. Then get or make a airlock. The first few days can be done In a bucket with a tight weave towel, but then you want to get it into a jug to keep the air out but let pressure escape. Even If you can find active dry bread yeast, that would be a sure bet compared to going wild. Otherwise, do as Bernardsmith mentioned to grow your own yeast first, then if it works, add it to more juice or grapes. It can be as simple as this

I was aiming for 10%, which is half the amount of sugar you would put, as I heard. Is that because the alcohol torelance of indigenois yeast is too weak?

 

[madscientist451]

Go ahead and use the bread yeast. If you can get honey, just use bread yeast, honey and water, make a mead, then add your grapes or other fruit for some flavor near the end. You can use all sugar instead of honey, but the flavor will be better with honey.

 

[Seamonkey84]

I was aiming for 10%, which is half the amount of sugar you would put, as I heard. Is that because the alcohol torelance of indigenois yeast is too weak?

I may have read your post wrong. Did you include the water that you used to disinfect the jar with or just the 500g of grapes?

As for making It a mead or sugar wash, if you don’t have access to yeast nutrients, add the fruit (and more of it) in as part of the ferment to provide the nutrients and make it more wine like. Putting the fruit in secondary will likely restart fermentation anyway, so might as well provide the yeast the nutrients from the beginning.