Fruit spoiling during AF?

[RottenGrapeJuice]

Hey does anyone have any tricks to prevent fruit from spoiling (going sour) during AF? I tried to make fig wine last year and it has some off aromas. I noticed toward the end of AF the figs floating didn’t smell very good (figs have a shelf life of a day or two). I believe a similar thing happened with my strawberry wine. Would it help to submerge the fruit?

 

[Rice_Guy]

The standard process when pulp is in the must is to mix the solids one or three times a day. This prevents dry material from developing which can grow mold/ develop off flavors.

How is your gravity changing with time? There are acids in fruit which are masked by the high sugar content. Acid flavors (as well as tannin/ long bitter) will become obvious when the gravity goes below 1.010. When you have a finished wine back sweetening is typically done to put acid and sweet and tannin flavors back in balance.
Meaty/ sulfur aroma? Yeast which has low YAN (yeast available nitrogen) can develop what one of the club members calls fried chicken flavor which can overpower fruity aromas. What was the nutrient regemine?

 

[RottenGrapeJuice]

Well mixing three times a day is standard practice for me. Gravity was steady to 0.996 within a week if I remember (this was last year). I guess the better question is this: what makes fruit go sour? If it is spoilage bacteria and yeasts, then maybe I just didn’t balance my pH properly (I vaguely remember it being high when I started).

I did sulfite the must the day before pitching yeast, so that should have helped, but if the pH was off then it may have not been enough.

 

[Rice_Guy]

Sour is the normal result of a lactic fermentation where alcohol isn’t produced (ex sour kraut). Lactic acid bacteria are killed at alcohol levels above 5% so a yeast fermentation eventually, hopefully quickly dominates.

Fruit should taste sour/ acidic as an example pH from strawberry 2017 to 2021; 3.6, 3.57, 3.50, 4.01, 3.45 (with a TA of 1.10%)

 

[RottenGrapeJuice]

I think figs typically have a ph of mid 4s. I adjusted with tartaric acid, but are there detriments to heavy acid adjustments? I believe some bacteria feed off tartaric acid, so not sure if heavy amounts of it would leave the wine vulnerable. I don’t have the ability to measure TA at this point.

 

[salcoco]

sometimes the lag phase prior to active fermentation will cause some spoilage of the fruit. recommend establishing a yeast starter. the heavy fermentation of the starter will reduce the lag phase and the earlier fermentation will help in preventing spoilage as you press down each day.

 

[Jstapon]

Well hello again people, I'm happy to tell everyone that after diluting my over salinated blueberry must(with sodium metibisulfate to stop natural fermentation) and topping up sugar content and adjusting acid levels, I managed to start a culture and pitch it, boy oh boy did it take off. The entire must was rolling like a tornado, truly a welcome sight. After 5 days the fruit skins started to pile up and lifted the primary lid right off so I had to remove alot of them, but thats ok, the skins from the berries did thier job and left behind the tannin levels I was after, in a few more days I will rack into my secondary fermenters and strain the remaining pulp and skins from the must, any fruit left in it could cause off flavors or taint the batch because of air trapped in the mass, this causes the fruit to decompose, not good for wine to say the least, as the yeast population starts to deminish any fruit that floats should be removed, that way the last of the culture can work effectively and there is nothing to trap air in the must, thereby avoiding decomposition and a not very tasty wine. If its on the bottom then it doesn't have air trapped in it, if its on top remove it before it rots and ruins your investment. If I find white blueberries in the strainer its already too late. I never like taking chances with fruit during secondary fermentation and have always removed effluent when transferring into the secondary fermenters. If you add orange slices to the top of peach wine during secondary fermentation for a little more acid to remove pectic haze, you have to check them every day because they will rot due to exposure.