Why is mold more common in cucumber ferments than in sauerkraut?

I find it really strange, that even if I use the exact same amount of salt (1.5%) to the total weight of what is in the jar, I've never had mold grow on the surface of my brine in any of my sauerkrauts, but seems to be very common when I do cucumbers. And this is all considering that I may ferment them at roughly the same time of the year, using the same type of jar, the same type of weight, fully submerged under brine, with a silicone airlock, never opened while fermenting to avoid oxygen getting in etc.

Is this because cucumbers naturally have more mold than cabbage? Or perhaps cabbage has anti-mold properties?

Or could it be because I am using filtered tap water that hasn't been boiled and cooled?

Or could it simply be that cucumbers have less sugar, meaning that the fermentation is too slow, and the lack of acidity is causing mold to grow?

I'd love to use 1.5% to total weight, and let it ferment in room temperature for 2 weeks and have a very sour ready to eat pickle, but it always creeps me out when I see fuzzy white jelly fish floating in my brine. So far in my experience, even 2 weeks isn't sour enough for me, I'd probably need to leave it for another week.

If it is due to lack of sugar, how much table sugar should I use as a percent of the total weight? My jars are about 1.5L each, meaning that I can fit either 1500g of cabbage, or 750g of cucumbers into them. 1500g of cabbage contains 48g of sugar, whereas 750g of cucumbers only contains 12.5g sugar. Does this mean that I should add 35.5g of sugar into my cucumbers to match the sugar of cabbage?

Otherwise, is there something I can add that will act as an anti-mold without affecting the lactic acid bacteria?

Thanks!

Is it white/cream colored film? If so you probably have “kahm yeast” which is not dangerous, just unappetizing.  See this on what it is and how to minimize: Fermentools on kahm yeast

I have read it is more likely when fermenting whole vegetables rather than chopped, so maybe that’s the difference with your pickles.

Thanks for your reply. No it wasn't yeast, it was fuzzy.

I'm not sure this is the answer, but I think I recall cucumbers are actually designed to rot, specifically from the end. I wonder if this would translate into intentional ferments? I think I recall something about them keeping better if you cut the end of. I wonder if omitting the ends from the ferment might help prevent mold?

Not sure, I've heard of people saying that cutting the blossom end of cucumbers helps to prevent softening due to an enzyme.

I'm going to make another batch of cucumbers, but this time, I'm going to boil my water, add extra sugar, and also add some cayenne pepper into the brine and see what happens.

If I get mold again, I might have to purchase one of those vacuum pump fermenting lids such as "The Easy Fermenter". No idea if that will make any difference.

There may be some insights into your problem in this link on fermentation of pickles vs. cabbage:  https://faculty.weber.edu/coberg/class/3853/3853%20vegetable%20fermentation.htm

In Germany widely used in households and with a long history is "Gurkendoktor" Translated like "Cucumberdoctor"

Keeps the Cucumber crunchy and inhibits the growth of mold.

I made it in Thailand myself because of the lack of availability of Gurkendoktor.
Relatively harmless stuff where I stay far under any limits made of:

Calcium acetate 2 grs per Kilo
Sodium Benzoate maximum 0.1%  (it's the only ingredient thats limited by the food industry, but here I go a bit less like 0.05%
Potassium sorbate 300 mg per Kilo

Depends on climate humidity, spawn in the air you might experiment a little for yourself.
Now where I have my farm I want to pickle cucumbers again and if I sell the pickles Gurkendoktor is not to avoid.  

I hope it helps...

See Hes wrote:In Germany widely used in households and with a long history is "Gurkendoktor" Translated like "Cucumberdoctor"

I was not familiar with this product (there is no history of gardening or canning/preserving in my family).
But is it actually helpful in fermentation as well? From reading the description on the vendor site I deduce it is for traditional (vinegar) pickles. Have you tried it in fermenting already?

I was not familiar with this product (there is no history of gardening or canning/preserving in my family).
But is it actually helpful in fermentation as well? From reading the description on the vendor site I deduce it is for traditional (vinegar) pickles. Have you tried it in fermenting already?

Whenever I am pickling cucumbers I use it as my mother and grandmother did.

Since everything is available online I use now "Alba Gurkendoktor" or "Ostman Gurkenfest"
If you google it, you will find it for sure also in your Country.

It keeps the cucumbers crispy and avoids mold.
Gurkendoktor must be on the Market for almost a century if we are looking at this promotion from a Newspaper out of the 40s.
The design of the 15 grs bag has only slightly changed (around the 50s my best guess)

See Hes, when you say "pickling", do you mean pickling in salt-water? Or vinegar?

Anthony Marc wrote:See Hes, when you say "pickling", do you mean pickling in salt-water? Or vinegar?

Pickling might be my "Germlish" but I guess its for working with vinegar.

I do various ways because of my Thai in Laws.
What for me sweet sour is makes they faces wrinkly and is way too sour.

Here the different ways in one recipe.

2.5 kg pickling cucumbers (preferably the Nostrano variety) approx. 3.5 liters of water
Sea salt unrefined (40 g - 50 g salt / liter) (no iodized salt !! otherwise the pickles will go bad.)
1-2 bunches of dill
fresh horseradish if available (to keep the cucumbers crunchy for as long as possible)
Grape leaves or black currant leaves or sour cherry leaves  (Tannin containing leaves does the trick)

1 tablespoon lemon juice per liter of water
or 1 tsp cucumber doctor
or 1 teaspoon of vinegar essence per liter of water
Here gave me Cucumber Doctor the best results and made them even more and longer crunchy.

optional: fresh tarragon; bay leaves; Onion rings; mustard seeds (mustard seeds); 1 tbsp peppercorns;
1-5 cloves of garlic, depending on taste what you like.

Honey I add for my in Laws

I kept many in my fermenting pot but also canned a lot for a long shelf life..

set up:
Use only hard and damage free cucumbers. Check especially both ends where mold can hide.
Put them in layers in the fermentation pot. I have 3 classic 15 liter sauerkraut pots.
A layer consists of 1-3 grape leaves, 2-4 sour cherry leaves, 1 stick of dill, 1/2 clove of garlic, 3 slices of horseradish and as many cucumbers as you can fit next to each other.
Keep the Cucumbers ALWAYS covered with brine.

Anthony, not sure what your climate is like.... i used to ferment cucumber pickles in the US and when I moved to South America (zone 9b, not very hot but still hotter/wetter than where I was in the US) I was unable to ferment a cucumber to save my life. To this day I make vinegar refrigerator pickles, not lacto ferments, because it just never works. Cabbage and other veg work fine, go figure. I'm blaming the climate.

Thanks See Hes, that's very interesting. Do you think the 1 tablespoon of lemon juice will help prevent mold? Or is it just for the crunch?

Any other tricks to prevent mold other than Cucumber Doctor?

I think you might need to use more salt. Cucumbers have way more water in them than cabbage, so your brine is getting diluted as the water in the cucumbers comes out. I've seen recommendations for more like 4-5% salt for cucumbers.

Yeah, I point folks to this process for getting started with sour pickles: https://www.wildfermentation.com/making-sour-pickles-2/

I've had batches get mushy but never mold. And I mostly make them in open-topped 5-gallon buckets with a weighted plate, no air-lock.

Anthony Marc wrote:Thanks See Hes, that's very interesting. Do you think the 1 tablespoon of lemon juice will help prevent mold? Or is it just for the crunch?

Any other tricks to prevent mold other than Cucumber Doctor?

Lemon is definitely for disinfection because I killed once my Bacteria in my home Aquaponicssystem as I used a Bottle of Lemon Juice to clean the pipes.

As in wine you want to achieve a quick fermentation start up.
(it might help to puncture too waterish cucumber's skin 4-5 times with a toothpick)
To avoid mold the trick is acid (which Gurkendoctor is based on)

The leaves help also because they all contain Tannin, that's why I put them between the layers, but also for the taste.

Awesome, thanks everyone for your kind help. I have just made a new batch of cucumbers (1.5L jar, holding 750g baby cucumbers), this time, I used 1.5% salt to total weight (equivalent to 3.4% salt to water weight) + 35g sugar + 1 Tbsp lemon juice (per litre) + 1/4 tsp cayenne pepper (per litre).

I have boiled the water and allowed to cool in the refrigerator until cold before pouring the brine in. Regarding the salt amount, I am well aware that 5% salt to water weight (equivalent to 2.23% salt to total weight) is typical, however, my mum is very sensitive to salt, and so it was important for me to keep it at the same level that is in sauerkraut.

Let's see what happens in 2 weeks time!

If I get mold again, I'm buying a vacuum fermenting lid.

Grapes naturally have a huge reservoir of alcohol microbes (yeast),
and cabbage naturally have alot of pickle bacteria,
and it make sense that cucumber naturally have alot of mold microbes.

So once we add water it is going to multiply the pre-exisiting population of microbes. It might be a good idea to use the starter from a cabbage batch to jump-start the cucumber batch.  

Anthony Marc wrote: Regarding the salt amount, I am well aware that 5% salt to water weight (equivalent to 2.23% salt to total weight) is typical, however, my mum is very sensitive to salt

This is why I don't eat much lacto fermented stuff - waaaaaay too salty. I stick mainly to yoghurt, kefir and ginger bugs for my raw ferments.

Jan White wrote:I stick mainly to yoghurt, kefir and ginger bugs for my raw ferments.

First time I ever heard of 'ginger bugs', had to look it up to see what it was. What does it taste like? Do you have any good recipes? Any molding issues? I'm assuming that this is a bacteria ferment, not yeast based?

Like a sourdough starter, a ginger bug is a combination of bacteria and yeast, and probably a little different every time you make it. When I've made them, what they taste like isn't all that important because I use it to make naturally fermented soda-pop / carbonated tonic beverages -- ginger beer, etc. I'm interested to hear if Jan uses the bug as a food.

A ginger bug just tastes like ginger 😁. Generally I use them as Christopher has described.  I made a very nice, fizzy elderflower drink a couple years ago - just brewed some elderflower tea, added the bug liquid and some sugar, then sealed it up in bottles. I only really make something like that once or twice a year because I avoid refined sugar. I try to let it brew until it's quite dry, but I'm haphazard about things, so it's hit or miss.

Once the ginger's been strained out, I'll add it to tahini, miso, and rice vinegar to make a salad dressing, so I guess that's kinda food.

Oh, I guess I get fermented goodness from live vinegars, too. They're super easy to make with whatever fruit you have available to you. I've got elderberry, strawberry, chokecherry, and pineapple at the moment.

Oh, as far as ginger bug recipes go, I just look it up on the first website that comes up in a search. Since I do it so infrequently, I never remember the ratios. Whatever comes up seems to work fine.

I've never had any mold, but occasionally I've had a nice fizzy bug that refused to cooperate with a second ferment - I'd open what was supposed to be a fizzy bottle and just have flat, sweet tea. Easy enough to just add a new bug and try again.

There are warnings about using only organic ginger, since the bacteria is all on the skin and you need to use it unpeeled. I've never used anything other than conventionally grown, peeled ginger and never had a problem getting one going.

They're very forgiving.

Just thought I'd post an update. 35g of sugar was probably too much. Getting a lot of white sediment after 9 days. Probably a quarter this amount would have been better for a 2 week ferment, or half the amount for a 1 week ferment. They are very sour, but they're also sour in an acetic-acid kind of way.

Next time I will drop sugar by half for a 1 week ferment and leave out the lemon juice and see what happens. Cucumbers are crunchy, but also somewhat hollowed out. Definitely if I had left them for 2 weeks they'd likely become empty balloons.