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What do people do with oil used for deep frying?

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My mum used to store the deep fry pot (with oil) on a shelf in the kitchen, and then reuse it. I now imagine that I would find the taste of the old oil off-putting.

 

I can't remember when I last did any deep frying.

 

Also, of course, deep fat frying is probably unhealthy. Are people satisfied with the "air fryer" alternatives?

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If you want my honest answer:  I spill it on the counter.  Some goes on the floor.

 

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Serioyus Eats addrressed the issue the other day probably for Passover frying. .   Hopefully our master fry folki like @Shelby and @HungryChris  If done properly your food should be crisp and not oily.  If you measure before and af6ter there shoud be only a slight difference,    https://www.seriouseats.com/2019/04/how-to-dispose-of-cooking-oil.html

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I bring an empty large (16 liter) oil container home from work. I dump the cooled oil in it, put the lid on and store it on the stairs to the attic (which are behind a door located in the kitchen). When it's full, I take it to work and leave it with the ones from work to be disposed of by whoever picks all that up and I take another empty home to start the process again. But I realize that's not an option for everybody.

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It depends on what has been deep fried in the oil. Oil for chips/fries, I will happily, filter, store in a covered metal pot which sits on the counter and re-use once or even twice.

 

Oil used for fish or anything spicy, I dispose of after one use. I have a 5-litre old oil bottle under the sink and used oil is put there until full, then properly disposed of.

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I'm with @liuzhou. I have filtered (through cheesecloth or paper towels) used oil as long as it's not used for fish, and kept it in the fridge and reused three or four times, maybe more. Fish-frying oil gets dumped in an empty glass jar and tossed in the trash.

 

When I was a kid, we lived out in the country and, to minimize trips to the dump, burned a lot of our trash in a big 55-gallon barrel. We'd just pour fish oil, or oil that had gone off after several uses) on that and burn away.

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I will reuse oil that has been used for fries only.     And just once or twice before disposing of it.  

 

I can dispose of cooking in in a milk carton in with out weekly "organics/compost" pick up. 

 

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Posted (edited)

Brand new oil is actually not as good as "older" fry oil, as slightly heat-damaged lipids are better at making physical contact with the surface of food (I believe for ionic reasons, if I recall my Dave Arnold correctly). At any rate, brand new fry oil isn't ideal for producing a brown crust as easily. That's not why I save my oil... but it's a good story to tell to myself while I'm filtering the oil and putting it back in the jar. I "backslop" old oil back into the main container, but only if it's been used to fry clean-tasting foods like potatoes. If fish or brassicas or some other such thing got fried in there, I end up disposing it.

 

I use high oleic sunflower oil for most of my deep frying needs. It hits the right balance between having a healthy lipid profile, high smoke point, neutral flavor, and relatively low cost. There's probably something better out there, but I haven't had the time (or the need) to explore the options in depth. Most industrial seed oils used for deep frying are a freaking nightmare on your body from a health perspective (though that's a matter for another forum). I also like to use lard and tallow from pastured pigs and cows. For different reasons, and for different applications.

 

The flavor of french fries made in beef tallow is superb. Apparently, if Steingarten is to be believed, a mixture of half horse fat and half beef fat tastes even better. But that beef fat french fry flavor is the core of the OG McDonald's french fry -- the Original Platonic Form of the French Fry in the American imagination. That was before the damned vegetarians and their health-nut disciples forced an industry-wide switch over from saturated animal fats to hydrogenated vegetable oils. Stupid jerks. How'd that work out for us? Want to ban trans-fats now? Guess who brought those into our dietary system, jerks!!! But I digress....


Lard also makes good french fries. Great onion rings. But it's the bee's knees for fried chicken. Chicken fried in lard? Yes. Throw in some fresh bacon fat and some rendered fatty funk from a country ham? Hell yes. Lard has a lot of monounsaturated fats compared to tallow, which makes it much more fragile from a heat stability standpoint. You can't reuse it over and over like you can with tallow. But if you're making fancy fried chicken for family supper on a Sunday afternoon? Boy howdy, get you some lard and get frying. You may well have to throw the fat away afterwards... but to think of the spent fat as "waste" is to have missed the magical work it did for you.


Edited by btbyrd (log)
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1 hour ago, btbyrd said:

as slightly heat-damaged lipids are better at making physical contact with the surface of food (I believe for ionic reasons, if I recall my Dave Arnold correctly).

 

If you have a reference for this it would be highly appreciated !

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It was on one of the back episodes of Cooking Issues. But the issue of polarity impacting the consistency of fried foods is well documented at the commercial level. Here's an article on monitoring polar compounds in fryer oil. A relevant nugget:

 

"Total Polar Compounds affect the consistency of deep frying by increasing the release of water and the absorption of fats into the product. French fries, for instance, will brown but will be hollow because the moisture has been released too quickly."

 

 

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3 minutes ago, Duvel said:

 

If you have a reference for this it would be highly appreciated !

I don't know the exact chemistry, but from what I understand of it, used oil has more "soaps" which allow better contact between the watery food and the oil.  Shirley Corriher had a whole thing about it - and I believe it's in McGee as well.

 

But on that topic, it turns out that you really don't need that much old oil...  I've always heard it recommended that when you dispose of old oil that's been used a few times, to save a few tablespoons of it and add it to the new oil... evidently, that's really all the soap you need...

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1 minute ago, KennethT said:

don't know the exact chemistry, but from what I understand of it, used oil has more "soaps" which allow better contact between the watery food and the oil.  Shirley Corriher had a whole thing about it - and I believe it's in McGee as well

 

That sounds meaningful. I’ll check that, but if anyone has a bibliographic reference available I’ll be grateful ...

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There's some surface activity stuff going on there too, for sure. I'll go reread Shirley Corriher, as it's been a while. She doesn't get nearly enough play! I don't know who McGee's agent is... but maybe she should switch over. 🙂 

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Posted (edited)

Okay... some nuggets from Shirley. Cookwise is an AWESOME book, and her section on frying is fantastic.

 

"New crops like high oleic sunflower oil and low linolenic soybean oil maximize single double bonds and minmize double and triple double bonds, making for more stable and healthful oils. The more healthful unsaturated fats can be used if the oil is not going to be re-used. Considerations like flavor and smoke point may be more important than saturation." (158)

 

That's basically why I keep HO sunflower oil and tallow on hand. Tallow is super stable (and not terrible for you, if your cow didn't spend the last two months of its life in a concentration camp). But for a vegetable-based option, HO sunflower oil is pretty dang good.

 

She does not recommend re-using fry-oil from home because it does not contain the common additives (like anti-oxidants) that help keep commercial fryer oil from breaking down. I don't fry that hot and I use relatively stable fats, so I don't know that this nugget applies across the board. You can always add some mixed tocopherols to your oil if you want to, and create your own "commercial" fry oil.

 

Commercial fry oils contain trace amounts of certain silicones, which form a film on the surface of the oil, preventing direct contact with oxygen in the air (and thereby limiting oxidative rancidity).

 

Solid vegetable shortenings often contain emulsifiers like mono and diglycerides, which makes them good fats to use in cakes but lowers their smoke point and makes them bad for higher temp frying.

 

I couldn't find anything on polarity and browning, but KennethT is right on the money that you don't need to add much "old" oil to fresh oil to reap the benefits of slightly damaged fry fats. The key is that the damage is *slight*. You don't want to slop back a bunch of burned up fishy-smelling rancid garbage oil into your jug. That's not going to be good for anyone.


Edited by btbyrd (log)
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Thanks. If that number behind your citation refers to an original article that would be the one I’d be interested in. Nevertheless, I’ll check tomorrow PubMed and its relatives ...

 

5 minutes ago, btbyrd said:

which form a film on the surface of the oil, preventing direct contact with oxygen in the air (and thereby limiting oxidative rancidity).

 

Sorry, but definitely not.

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2 minutes ago, Duvel said:

 

Sorry, but definitely not.

 

Meh?

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2 minutes ago, btbyrd said:

 

Meh?

 

Still sorry, but no.

 

Not to be dismissive, but the conclusion that this paper comes to is ridiculous. Correlating a concentration to a surface monolayer is next to impossible, given the nature of the experiment. I’ll look at the mechanisms from work tomorrow where my access to primary literature is slightly better ...

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It may be bunk, but the fry oil people have thought to add it in. I'm sure your scientific chops are better than my own. The use of silicones in fry oil might be a bunch of stupid industry nonsense (like vacuum marination of meat) but there's at least a purported rationale at work. I look forward to hearing what you're able to find out. I did a quick glance through what I have available to me, and found a couple things that may be interesting on the topic. Here's a relevant literature review and critical discussion from 2004:
 

Effectiveness of dimethylpolysiloxane during deep frying
Author: Márquez-Ruiz, Gloria
Journal: European journal of lipid science and technology
ISSN: 1438-7697
Date: 11/01/2004
Volume: 106
Issue: 11
Page: 752-758
DOI: 10.1002/ejlt.200400999
 
And another one purporting to establish the utility of DMPS in continuous frying operations.

Polydimethylsiloxane Shows Strong Protective Effects in Continuous Deep-Frying Operations
Author: Totani, Nagao
Journal: Journal of oleo science
ISSN: 1345-8957
Date: 2018
Volume: 67
Issue: 11
Page: 1389-1395
DOI: 10.5650/jos.ess18047
 
Maybe it's all a ruse by Big Silicone. Or maybe the food science guys just don't understand the mechanism properly. In any event, they're adding silicone to commercial fry oil in minute quantities in an effort to stave off oxidation. 
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10 hours ago, btbyrd said:

 

It may be bunk, but the fry oil people have thought to add it in

 

 

Don’t get me wrong: I am with you that the industry adds certain stabilisers to processed frying oils. I am interested in the underlying mechanisms (which for some at least are clear to me). The same for the improved frying properties of (reasonably) aged frying oil. 

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This isn't really disposal related... but I just wanted to encourage people to get frying.
 

 

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Posted (edited)
22 minutes ago, Yana Sizzzlers said:

 

Even I also used same type of oil for fish & for some time bbq. I like to ask something, What Is The Healthiest Oil For Deep Frying? 

 

 

What kind of oil do you use in your several restaurants in India?


Edited by liuzhou (log)

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1 minute ago, Yana Sizzzlers said:

soybean oil because it is neutral in flavor .

 

OK, but the question is how do you dispose of it?

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Deep frying in ghee is heavenly. And it is a very stable oil that can be reused. It also has a healthful lipid profile, if the cows were fed on pasture). Expensive, of course, but worth it for a special occasion.

 

If you are going to reuse fry oil, you've got to filter it somehow. Some dedicated fryers have a system that makes this easy, but I typically fry in cast iron on induction so I have no fancy built-in strainers on hand. So I'll filter it through a chinois or a tea strainer depending on the quantity. But Kenji has outlined a fun and creative way to clarify fry oil using gelatin. It's not vegan, of course... but it could be worth trying if you need to get those extra tiny bits of potato starch out of your beef tallow.

 

To get back to disposal issues, I usually pour my cooled fry oil into a ziptop bag and dispose of that with the other household waste. This is easiest with unsaturated fats, because they're liquid and you can just pour them out. Some find this method too messy or fussy, and the Japanese have a solution for them. There is a product called Katameru Tempuru which works to solidify used fry oil so that it's easier to dispose of. I cannot comment on the stuff myself, as pouring it into bags works fine for me. But there are several "cooking oil solidifiers" on the market, if you're in the market for such a thing. Some are even made by S.C. Johnson -- a family company. 

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