I've been fermenting veggies off and on for years and, while I've had the rare batch that didn't ferment, I've never ever had one grow mold until this last week where two of my ferments grew a white mold. The veggies were different and the jars were 5 or 6 feet from one another.
The first failure was a bunch of shredded carrot which I put into a Japanese pickle press which kept the carrot shreds under its own juice. I put a little bit of salt in. I do have to admit that I've never fermented carrots alone; I tend to put cabbage into everything which is the easiest thing in the world to ferment, in my experience. I wonder if all the sugar in the carrots were just begging the mold to grow!
The other failure was in my gallon jar, which has an airlock on the lid to let gases escape while keeping air out. I also filled it to close to the top (to minimize air in the jar). Veggies included shredded cabbage, carrot, turnip, and beets. I added water, some juice from fresh lemons (to acidify the brine and keep bad bugs out), and salt (also to keep the baddies out.) I open the lid once or maybe twice a day to check on it. Tonight there was a white film on top and the ferment smelled off. So, like its predecessor, this batch goes to feed the worms in the compost pile. :(
Any idea on what might have caused two different ferments to go bad? It's pretty warm in Santa Fe these days. Could mold spores be in the air (more than usual) due to the climate? Humidity is very low here. Wouldn't that discourage mold growth?
Mason jars are NOT anerobic so you won't be creating the anaerobic LAB you need
I highly recommend reading Kerryann Foster from "Cooking Traditional Foods" most recent series on lactofermentation. Our ancestors buried or sealed their ferments for the most part.
Found this from S.K.
Aerobic vs Anaerobic Fermentation Controversy Posted on May 8, 2012 by wildadmin I hear that much controversy is brewing on the internet over vessels for fermenting vegetables, and the implications of whether or not they are totally anaerobic. I have made hundreds of batches of kraut in all sorts of vessels (most of them open crocks), and I have witnessed, consistently, that it doesn’t matter. Each vessel has advantages and disadvantages. No particular type of vessel is critical. People have been fermenting vegetables for millennia in crocks open and closed, in pits and trenches, in sealed and open vessels. It can be done many different ways. The only critical factor is that the vegetables be submerged under brine.
Whenever vegetables are submerged under brine, lactic acid bacteria (which are anaerobic) develop. Whether or not the vessel protects the surface of the ferment from atmospheric oxygen, the microbial development under the brine is anaerobic lactic acid bacteria. In the vocabulary of microbiology, lactic acid bacteria are “facultative” in that they that do not require oxygen, but are not inhibited by its presence; in contrast, certain other bacteria (for example Clostridium botulinum) are “obligate” anaerobes that require a perfectly anaerobic environment.
The only difference air exposure or lack thereof makes is whether aerobic organisms like yeasts and molds can develop on the surface. The barrel of kraut I have had fermenting in the cellar for six months now is good and sour, and I have been eating from it and sharing it widely for months. Each time I remove the cloth tied down over it, and the jugs of water weighing it down, and the two semi-circular oak boards that rest upon the surface, I skim off a moldy layer around the edges and down the middle, wherever the surface was exposed to air. I toss the moldy layer into the compost, and the kraut beneath it looks, smells, and tastes wonderful. Many people have reported how good it made them feel and not a single person has complained of any problems from it, ever. The brine protects the vegetables from the aerobic organisms that grow on the exposed surfaces. The ferment is a lactic acid ferment, even though the surface is aerobic. Surface growth should be scraped away because if it is allowed to grow it can diminish the acidity of the kraut and affect flavor and texture, but if you keep periodically scraping mold away, the ferment beneath is fine.
I have also fermented in Harsch crocks, Pickl-Its, Mason Jars, and many other types of vessels. Mason jars become highly pressurized if you fail to loosen them to release pressure. Even if they are not perfectly airtight, they permit little airflow. Many times I have witnessed carbon dioxide force its way through the airtight seal by contorting the tops to provide an escape for the pressure. The various air-locked designs that allow pressure to release while preventing air from entering the system are generally effective at preventing aerobic surface growth. Yet still I generally do not use them because I love to look at and smell and taste my krauts as they develop, and each time you open an air-locked vessel you defeat its purpose, allowing air in. The vessels are effective, but are not well-suited to my desire to taste at frequent intervals. Different vessels suit different needs and desires. No one type of vessel is essential for fermenting vegetables. I have had success using every type of vessel I could think of. As long as you can keep vegetables submerged, lactic acid bacteria will develop. The process is extremely versatile.
For more in-depth information on fermenting vegetables, fermentation vessels, and all realms of fermentation, check out my new book, hot off the presses, The Art of Fermentation. Keep fermenting….
What was your salt to carrot ratio? Because carrots have a bit more sugar, they may need more salt, or more starter culture.
Temperature is another issue, because it is warmer, ferments can take shorter periods of time, or may not have time to develop the good bacteria before the bad bacteria takes over.
Also, the whole purpose of the airlock is to keep air out. By opening the jar a few times per day, you have defeated the purpose of the airlock.
KerryAnn, from cookingtf.com, gave me a very helpful answer when I posted the question on her web-site.
Humidity does encourage mold growth, but the conditions are right in a jar that contains oxygen for it to grow, humidity or not. In order to avoid mold, its mycotoxins and it’s tentacles reaching all through your ferment, you want to ferment in an oxygenless environment. Being able to give the oxygen a way to escape (it’s lighter than carbon dioxide) and prevent more from entering is key. I’ve had periods of time where every femrent I made molded, and looking back on it, I have to assume it was mostly to do with the climate at the time. Other folks have reported to me that they only have mold issues a certain part of the year. If you’ve changed something, like recently opening your windows from nice weather or a cool night, that can encourage mold spores to spread. Mold isn’t attracted to sugar, per se, but to any food substance it can consume while it has access to oxygen. The air is the critical factor- without air, mold will not grow, even if spores are present. If you put too much salt in a ferment, and not enough salt will encourage mold growth, but oxygen is the over-riding factor. Any system that grows mold isn’t airtight. Opening the jar regularly is counter-productive and can introduce spores in addition to introducing oxygen and removing the protective layer of carbon dioxide. Only open the jars when they need to be repacked or there’s another problem.
One of the best ferments I've had with dill pickles was one in an airlock jar where I overfilled it with water so there was no air at the top. Unfortunately it started to leak the brine through the airlock. Still, it came out just fine.
The next batch, I didn't fill it to the top and it got moldy to the point where I threw out the whole thing including the airlock since I didn't want to risk contaminating the next batch.