'Infection' smells yum!

[RichardC]

It started fermenting before introducing commercial yeast, and formed a thin, white, film, on top of the must, that resembles soap scum. The smell is SWEET but, nothing like how the fruit normally smells and is unlike any sweetness I'm accustomed to. ( when stirring, the expected smell dominates.)

I'm making a plum wine ( small, green plums that turn yellow when ripe. ) The plums were picked mostly half ripe, and had to be left a few days to ripen to some degree, before trying to ferment.

Sour flies were having a field day and admittedly, some fuzzy fungi on the plums likely ended up in the primary. I added over 1/4 TSP Metabisulphite to 2 1/2 gallons of must ( with seeds) yesterday to compensate for sour flies and possible fungi, but, obviously it wasn't enough. Lol

Q1) SHOULD I BE CONCERNED? I added sugar syrup, nutrients and yeast this morning, so expect kv1116 to become dominant, and now 5:40pm, it's fermenting as expected, but has the 'surface scum' and lovely, but odd, sweet smell.

Q2) ANY IDEAS of what it could be?

And to include everyone:
Q3) Do you intentionally make wines with wild yeasts, and how do they compare to wines made with commercial yeasts? ( in your experience.)

Q4) Have you ever had an unplanned fermentation?

Thanks

 

[VinesnBines]

Send pictures.

#4 I had a Petite Verdot begin fermentation before I picked up the crushed grapes. I pitched my yeast and it took off. I didn't see any scum but I had a cap of grapes so nothing formed on top.

 

[Rice_Guy]

From the description it sounds like flours, (an aerobic film former) a surface mold is another possibility.

It started fermenting before introducing commercial yeast, and formed a thin, white, film,
I'm making a plum wine ( small, green plums that turn yellow when ripe. ) The plums were picked mostly half ripe, and had to be left a few days to ripen to some degree, before trying to ferment. ,,, Sour flies were having a field day and admittedly, some fuzzy fungi on the plums likely ended up in the primary.
Q1) SHOULD I BE CONCERNED? I added sugar syrup, nutrients and yeast this morning, so expect kv1116 to become dominant,

It is normal to have every potential spoilage organism on the fruit that we start with. In the production of wine we build several selective barriers to encourage S. cerevisiae to become dominant. Was the pH below 3.5?, and the metabisulphite was in before the film, and the sugar was at 1.090 or higher? ,,,, each of these is a fence to prevent early spoilage. ,,,, the next fences to add are alcohol above 5% and limited/ no oxygen

At this point I would continue the fermentation, ,,, first check the pH (molds prefer above pH 4) remove the film with sanitizer soaked paper towel and rack to a carboy right away, ,,, create anaerobic conditions (molds require oxygen).
If the finished wine has an off flavor I would assume the spoilage organisms lived too long and toss

 

[Jim Welch]

I can’t answer Q3 directly but can point out that practically ALL yeasts (whether they be wine, bread, beer, or other) are and were “wild” yeasts until they were isolated and reproduced (I do not believe there are any that have been produced mind you but I’m not an expert) in a lab. Before microbiology was understood a batch of wine could be great, good, fair, or worse. It is quite possible for a “wild” yeast to be the same yeast one may buy in a sachet from a lab. It is more likely it isn’t though.
iirc there are around 1500 known species of yeast. For brewing, breakmaking, and wine making we are talking about just one species,Saccharomyces cerevisiae, of which there are thousands of strains. Some better for an application, some worse.
so you may have a good yeast at work there but it sounds like the die is cast and only time will tell.
An experiment!

 

[RichardC]

The images below show the 'scum' I'm talking about. In the close-up, the big bubble shows it clearly.
In a clean fermentation, bubbles are never this size.

Rice_Guy, I'm a little scared by your post! . 1) pH is LIKELY too high so, will get some limes and introduce acidity asap.
2) The wild yeasts/bacteria/ mold started work before adding sugar and pectic enzymes, so another possible red flag.( I thought sugar syrup was added the same time as nutrients and yeast, 12+hrs after adding sulphites, to reduce favorable conditions for wild stuff that comes with the fruit.)

My second wine was 'prebiotic ginger ' which did smell as yum but, after tasting with toilet paper in abundance, accepted that it was safe. Will have to go through a similar process here.

 

[VinesnBines]

Keep punching down the cap, more than twice a day to keep everything wet, and let the fermentation work/kill off the potential spoilage organisms. Believe your nose and taste buds.
I don't see anything of great concern - little fuzz maybe but punch it down and keep on plugging.

 

[Rice_Guy]

True at least through1950, all yeast were isolates of wild strains. ,,, AND true there are some interesting wild strains that are being found with modern fermentation’s, (ex MalurvurnB from Australia)
The UW biochem lab has done genetic modification(s) on yeast and done fermentations which the papers suggest as interesting ,,, but they are GMOs therefore need to go through the approval process before they could enter the food supply. A related food addition is that yeast produce (killer) metabolites which may eventually be purified and used as anti microbial chemicals.

I can’t answer Q3 directly but can point out that practically ALL yeasts (whether they be wine, bread, beer, or other) are and were “wild” yeasts until they were isolated and reproduced (I do not believe there are any that have been produced mind you but I’m not an expert) in a lab. Before microbiology was understood a batch of wine could be great, good, fair, or worse. It is quite possible for a “wild” yeast to be the same yeast one may buy in a sachet from a lab. It is more likely it isn’t though.

Have I used wild yeast? Not intentionally, but I did make apple juice last year that started fermenting and tasted good.

Background food science; pH is involved in many food preservation processes, to me a basic tool is checking the pH even if only using inexpensive pH paper

 

[Jim Welch]

True at least through1950, all yeast were isolates of wild strains. ,,, AND true there are some interesting wild strains that are being found with modern fermentation’s, (ex MalurvurnB from Australia)
The UW biochem lab has done genetic modification(s) on yeast and done fermentations which the papers suggest as interesting ,,, but they are GMOs therefore need to go through the approval process before they could enter the food supply. A related food addition is that yeast produce (killer) metabolites which may eventually be purified and used as anti microbial chemicals.

Have I used wild yeast? Not intentionally, but I did make apple juice last year that started fermenting and tasted good.

Background food science; pH is involved in many food preservation processes, to me a basic tool is checking the pH even if only using inexpensive pH paper

I stand corrected!
By GMO I take it you mean Genetically Modified Organism? If so, do you mean by insertion of DNA sequences or some other manipulation of the yeast's DNA? What is WU? I imagine the U stands for University?
I guess since yeast reproduce by budding they can not be cross bred like other plants or animals.

 

[sour_grapes]

What is WU? I imagine the U stands for University?

When he said UW, I am sure that @Rice_Guy was referrring to the University of Wisconsin, Madison.

I guess since yeast reproduce by budding they can not be cross bred like other plants or animals.

Yeast biology is complex. They mutiply by budding (i.e., mitosis) AND they mutilply by mating. They can stably exist in haploid and diploid forms, and they can undergo meiosis as well as mitosis.
Mating of yeast - Wikipedia

 

[Rice_Guy]

By GMO I take it you mean Genetically Modified Organism? If so, do you mean by insertion of DNA sequences or some other manipulation of the yeast's DNA? What is WU? I imagine the U stands for University?
I guess since yeast reproduce by budding they can not be cross bred like other plants or animals.

UW = university of Wisconsin
yes they are playing with yeast DNA, it is faster, ,,, it has been decades since I took micro but my understanding was that eucariots occasionally did exchange genetic material, ,,,, example, Hybrid yeast produces tasty Belgian beers
As a family they are adapted to a wide variety of habitats and carbon sources. ,,, Wiley Publishing will let you browse their titles on yeast to get some feel where current research is going.

 

[BernardSmith]

Even if every lab cultured yeast began life as an indigenous yeast the labs have cultured and cultivated these yeast strains much like over the the history of civilization we cultured and cultivated grasses to produce what we now think of as wheat and corn, barley, spelt and oats. In other words, preferred offspring were encouraged to grow and multiply and dispreferred outcomes were discarded. And more: preferred offspring were not simply accidents of nature but were the result of human intervention and design. Think of apples and tulips.

 

[RichardC]

Update: Hahahah. There was a sourfly just chilling inside the bucket when i opened it up to separate the fruit! Likely I didn't close it properly and neglected to tie cloth over the closed bucked to prevent flies from getting in. Haha.

Either way, a couple days ago, I added 2lbs more sugar syrup to ensure ABV is adequate. No initial gravity readings were taken but, given added sugar, amount of fruit, and volume of must, i estimate ABV to be 11-12%..

Taste is good! I didn't notice the weird, sweet, smell from before and can't wait to rack again! ( used coarse mesh bag, so there is still some fruit pulp to rack wine off of, so I'll give it a couple weeks, rack and add sulphites. )