What you see: Cloudy pickle brine.
What it is: If it’s a fermented pickle, the cloudiness is bacteria–the good kind!
Eat or toss: If it’s a fermented pickle and nothing else is amiss, eat! (And don’t forget to drink or cook with the brine too!)
Lactic acid bacteria cause cloudiness in fermented pickles
Central to pickle fermentation (and lots of other food fermentations) are a diverse group of round and rod-shaped microbes lovingly known as LAB, or lactic acid bacteria.
The various types of lactic acid bacteria are so named because they turn sugars into, you guessed it, lactic acid.*
LAB help preserve foods by creating an acidic environment where other microbes, including those that might spoil food or cause human disease, struggle to survive. Lactic acid also provides the tanginess you associate with foods like yogurt, pickles, sauerkraut and kimchi.
But, back to that cloudy pickle brine. These days, lots of pickles are made with a vinegar process that doesn’t involve lactic acid fermentation and results in a clear brine. But if you buy fermented pickles, you’ll likely see a cloudy brine and possibly some sediment at the bottom of the jar.
Billions of bacteria make brine look cloudy
You are, in fact, seeing the lactic acid bacteria themselves! While you couldn’t see an individual bacterium with the naked eye, when they number in the billions, which is pretty typical for a jar of pickles, you see them as murkiness and sediment.
You may be wondering if the bacteria are still alive and still churning out more lactic acid. Robert L. Buchanan, professor emeritus in the Department of Nutrition and Food Science at the University of Maryland, told me that jarred pickles are typically heat treated after fermentation and packing to extend their shelf life. This kills the bacteria.
But pickles that aren’t jarred are a little different.
“If you are buying pickles in a deli that has a large barrel, there is a strong probability that the pickles have not been heat treated after fermentation,” he said in an email. “However, by the time the fermentation is done there is little, if any, sugar left in the pickle to ferment and the bacteria are in a state of reduced metabolic activity.”
So, if your jar of pickles hasn’t been heat treated, it could get cloudier over time. But if the bacteria have already “finished the job” there may not be much sugar left for them to munch on so the cloudiness may not increase.
Other causes of cloudy pickle brine
If your pickles were made with a vinegar treatment, rather than a lactic acid fermentation, the murkiness could have other causes. Anti-caking agents in table salts can cloud brine (that’s why recipes specifically call for “pickling salt”).
According to the Clemson University Cooperative Extension, hard water can also lead to cloudy brine. If your non-fermented pickle brine is looking cloudy you should also check for signs of spoilage, which include mushy pickles and an off odor. Without such indicators, Clemson’s extension service reports, the pickles should still be fine to eat.
But if you see mold in the pickles, that’s a toss
While cloudiness in a fermented pickle brine is a sign of good microbiological activity, you should never see mold on the brine’s surface, Buchanan said. That means too much oxygen has disrupted the normal process and allowed uninvited microbes to grow. In this case, the pickles should be tossed.
Cloudy or clear, pickle brine is good to drink!
Once you finish eating the pickles, make good use of that brine! Pickle brine is great in salad dressings, potato salad, and egg salad, and can even be a flavorful substitute for some of the water in your favorite recipe for bread.
*While the term “lactic acid” may make you think of lactose, the sugar in milk, lactose is not necessary for LAB fermentation. Different types of lactic acid bacteria can turn different sugars into lactic acid.
- Robert L. Buchanan, Professor Emeritus. Department of Nutrition and Food Science and Center for Food Safety and Security Systems. University of Maryland.
- Common Pickle Problems. Factsheet. Aug 26, 2020. Clemson University Cooperative Extension Service. Home and Garden Information Center. Clemson University.
- Cloudy Pickle Brine is the Best Kind of Brine. Bubbie’s Fine Foods. May 16, 2018.
- What’s up with cloudy brine? Olykraut. Aug. 19, 2020.
- Pickle Fact Sheet. Oregon State University Extension Service. OSU Master Food Preserver Program. Revised March 2020
- How to make fermented pickles. University of Minnesota Extension. Suzanne Driessen, Extension educator. Reviewed 2021.
- Lactic acid bacterium. Britannica.