Adding fruit juice after finished fermentation

[Rice_Guy]

If citric acid is turned into acetic acid, I'm not using any more acid blend in my wine. I sure would have thought the companies that make that stuff would know better than to make it with 50% citric acid.

As wine makers we fight the conditions that create acetic acid, , , generally called exposure to excess oxygen with naturally occurring bacteria.

If yeast could metabolize anaerobic citric acid and produce acetic acid in levels that are detectable (ppm), , , everyone one this list would decide not to use it the first time tried , , , everyone on this list would avoid country wine , , , and grandpa a hundred years ago would have advised that fruit wines are a really good preservative but don’t ever try to drink them.

Our collective experience is oxygen is the risk factor for acetic acid.

 

[Rice_Guy]

a reference: Wine Faults, Causes, Effects, Cures; John Huddleston Ph.D. 2011,
“causes of Acetic Acid
Numerous microbes produce VA in wine, the most important being the following:
* Acetobacter and Gluconobacter, which are aerobic (oxygen requiring) bacteria.
* Lactic acid Bacteria (LAB), although some varieties more than others.
* Wild yeast strains, such as Kloeckera apiculata, Pechia membranaefaciens and, to a lesser degree, some strains of Saccharomyces cerevisiae.
* Pediococcus bacteria, which are anaerobic and, therefore, a concern after bottling.
* Botrytis, which is found on damaged fruit, usually as a result of Acetobacter, which is carried in by fruit flies and bees.
* Brettanomyces and its telemorph Deckers cause acetic acid in the presence of oxygen.”

the key is the phrase SOME STRAINS . . of S cerevisiae.
Unfortunately this reference doesn’t mention citric acid metabolism

The next reference for overall reactions is Concepts in Wine Chemistry, second edition, Yair Margarita Ph.D, , , , ? where did I put it? ?

 

[Scooter68]

Wikipedia as a scientific source is about as trustworthy as the kid on the playground description of 'how to seduce a woman.'

Similarly there are endless publications on all kinds of topics (Often self-published) and especially YouTube videos that do more to demonstrate how ignorant people can be. Sadly many are out to make money or they just haven't got a clue - in the past year alone I watched a number of those "Living Off-the-Grid" YouTubers who repeated demonstrated how NOT to do things while thinking they are 'helping' others.

MY POINT: When investigating a subject to learn 'how to' proceed with caution and investigate as many sources as possible. Relying on just one or two sources can still provide you with info that is dead wrong or simply incomplete.


The acetic acid problem arises only when a wine maker allows the conditions and materials (bacteria) to produce acetic acid to exist in their wine. Thousands, probably millions, of people have made wine quite successfully with citric acid in a large percentage in their wine. It only takes a few reasonable precautions to prevent the problem from ever ruining a wine. Acid Blend contains citric acid because it works, not because it's cheaper or easier.

 

[BernardSmith]

I would go even further than that Scooter68. Acid blend contains citric acid because many, many fruits contain citric acid and if you are making wines from those fruits you may want/need to add some additional acidity, but
if you added only tartaric acid - the dominant wine in grapes, or malic acid, the dominant wine in apples your wine would take on flavors that would be somewhat alien. Adding either citric acid or a blend that includes citric acid means that the flavors coming from the acid additions better match the fruit "substrate".

 

[stickman]

As was stated earlier, using citric acid doesn't automatically cause VA. The main issue is when citric acid is added to a wine that is intended to go through ML fermentation. Generally wines going through ML are not protected by so2 until after completion, so the citric acid is at risk of being consumed. Excess diacetyl (butter aromatic) may be produced as well as an increased risk of higher than normal levels of VA. Much depends on the wine pH and the microbes present.

The following is from Lallemand, DR. SIBYLLE KRIEGER.

"Trials conducted using simultaneous bacterial and yeast inoculation vs. bacterial inoculation upon completion of the alcohol fermentation showed no significant difference in the final acetic acid concentration, but a direct relationship between citric acid degradation and an increase in acetic acid concentration was demonstrated. Depending on the availability of oxygen and the oxidation-reduction potential of the medium, citric acid can either be used as an electron acceptor, which will result in acetic acid production, or it can be degraded to diacetyl."

 

[user 36973]

The main issue is when citric acid is added to a wine that is intended to go through ML fermentation.

Bingo