fryer oil got moldy

As someone who used to store hundreds of gallons of used cooking oil, I can attest that it is the water that causes the mold.

I filter my small batches of oil into qt Mason jars. I use a canning funnel and put a #4 coffee cone filter in it.It filters best when it real warm. Used oil will smell rancid when it goes and while it's harmless after heating, it taste terrible.

Potatoes and especially frozen french fries have a lot of moisture in them.
Might have been a contributing factor.


I don't care much for Castrol GT in the fryer. Aviation turbine synthetic. Won't smoke until metal melts. :)

Here are a couple rules of thumb for dealing with used fryer oil. This comes from some cooking classes taken in years past.

Generally speaking, any fryer oil that was used to fry a protein in the household environment should be discarded. Reason being is that you are just not going to use the oil frequently enough for it to last and most households don't have the filtration equipment necessary to get contaminants out of the oil. Restaurants typically change out their oil at least once a week and filter once a day.

If you are frying non-proteins at home, you can save and re-use it 3-4 times if you filter it through a couple coffee filters first. Used oil can be stored in the same container it came in and in a cool, dry, dark place for up to a couple months (two, perhaps three).

You should *NOT* put used oil in the fridge or freezer. Moisture will develop with the change in temperature and this will become enormously dangerous when the oil is re-introduced to the fryer.

Those of us who fry with any regularity know that optimum flavor isn't achieved until the 3rd or 4th fry cycle. If you fry foods often enough, take some of your used oil and put it in with your new oil before frying. This way, you are starting out with some of that "goodness" in your new batch of fry oil.

Mold also has to have moisture and apparently all the moisture from the potatoes didn't evaporate.

I think the mold starts in any tiny pieces of food left in the oil. Even cold grease molds if there are any bits of food in it.

It also helps to cheese cloth the cooled oil to reduce the solids which is probably where the mold comes from.

It was pretty warm and humid out while it was stored back in the jugs and then placed in an empty cooler in the camper. It was brand new oil used just the one time to make some fries. Guess I just need to use it more often and keep it in the fridge, Fridge is always empty between camping trips anyway beside condiments and booze anyway.

How warm was it while the oil was stored? Warmer temps or high humidity can cause it to go bad sooner.

Also how dirty was the oil when put into storage.

I have corn oil that I bought from Costco, and bought a 5 gallon container. I never put the new stuff in the refrigerator, yet my home is normally at 65 - 72F, so it stays reasonably cool all the time. The used oil is heated about every week or so to 350F, so it stays clean enough, and is filtered every once in a while, and changed about monthly (when discolored).

I guess I am not as interested in saving money as I am at eating good tasting food. I find that store brands do not have the same quality as the name brand products.

Next time you are looking at peaches, look at the large can. It might say slices and peices, and be lower cost per ounce. But half peaches have to be almost perfect peach to go into the can un-damaged. A blemish, and then the peach has to go into a sliced peach can, or one of the bulk cans that say peices. So the best quality peaches, without a blemish are peach halfs.

One person said they toured the pineapple factory in Hawaii. After the tour was mid-way through the canning process, they stopped producing Dole, and started making "Safeway" brand. So my guess is they produced many cans of higher quality fruit, then put the "Rejects" into another batch container. Once the good stuff was in the cans, they took the rejects and canned them under the safeway brand. The color of the fruit can change with the age of a tree, and will be more yellow, while less flavor fruit can be a little more white in color.

Another test to quality is in motor oil. My friend did a test with a solder iron. She put in a tablespoon of each oil into a metal pie pan, and put in the solder iron checking the seconds until it started to smoke. Castro GT oil lasted the longest time before smoking, thus the higher quality oil I use today.

Fred.

Used oil can go rancid very quickly unless you refrigerate it