Fruit Flies & Acetic Acid - Not Your Friends

Airlock Photo While fruit flies may be amazing little critters, for some scientists, they’re the last thing I want to study up-close in my lacto-fermented foods.

The water in the Pickl-It airlock is a barrier that not only reduces lacto-fermentation odors, that attract fruit flies, but also blocks them from entering the fermenting food!

Beyond the usual common sense reasons, of why fruit flies don’t make for appetizing food, a fascinating, science-based reason is they are carriers of acetobacter!

The Science Graphic Bacteria wars – a struggle for domination: Acetobacter – acetic acid bacteria – produce acetic acid, which are the bad guys in your lacto-fermented foods, crowding out the good guys – lactic-acid bacteria!

The Spring 2000 issue of Wine Maker Magazine, has a great discussion about acetic acid, introduced by fruit flies carrying acetobacter, as being a possible culprit causing wine to turn “foggy” and tasting like vinegar. The same ideas can be applied to our lacto-fermented foods!

Read the following excerpts for valuable lacto-fermentation information, substituting the words “pickles” or “sauerkraut” for “wine”. The principles are all the same.

  • Reduce oxygen during storage – decant larger Pickl-It contents to smaller storage containers; reduce oxygen airspace.
  • Maintain sanitary conditions.
  • Be aware the role fruit flies play in being a carrier of acetobacter which have a negative impact on your fermented foods.

Tiny Dill 500 Bar

Excerpt: Killer Bacteria & pH: Wine Wizard
Issue: Spring 2000

“Acetic acid bacteria live in wineries, on winery equipment and in the air. In fact, you’re probably breathing some in right now. Unfortunately, when these little guys come in contact with wine and oxygen, they tend to produce acetic acid, the stuff that makes vinegar smell and taste, so, well, vinegary….It’s very difficult for winemakers to totally eradicate them from the winemaking environment. All we can do is find ways to live with them.

Acetic acid bacteria need the following things to survive: oxygen, a hospitable environment and a food source. By controlling these factors we can reduce the chances that acetic acid bacteria will find, infect, survive in, breed in and make acetic acid in our wines. We can do this by the following:

  • Keep equipment scrupulously clean at all times.
  • Keep containers as full as possible, as acetic acid bacteria thrive in half-empty containers that are, by definition, half full of air.
  • Store your wines in a cool, dry area. The lower temperatures and dry air will discourage not only acetic acid bacteria but molds and fungi as well.
  • Finished wine, or wine that has just finished fermentation, is the most vulnerable to acetobacter attack since the protective layer of carbon dioxide produced during fermentation is no longer present. Keep these vulnerable wines especially clean and topped up.
  • Acetobacter are often transmitted to wines by insects like fruit flies. [That’s another advantage of the Pickl-It airlock, is that its water is a barrier, keeping fruit flies from entering.]
  • Do your best to clean up all spilled juice, must, skins and wine before you give fruit flies – and acetic acid bacteria – a chance to thrive in your winery.
  • Immediately clean up spills wherever they occur, and especially keep tops of barrels, carboys and fermenters clean and free of residue.
  • Even though airlocks and lids serve their purposes, air laden with oxygen and bacteria enters the carboy every time the fermentation lock is taken off [or the Pickl-It container is opened] to siphon out a carafe. I strongly suggest he bottle his wine or that he rack into smaller jugs as the level in his carboy gets lower. [Application to Pickl-It is that you should decant your fermented foods to smaller Pickl-It or other wire-bail containers in order to reduce the head space of oxygen.]