Deep fried foods have always been popular. They are a part of many traditional cuisines, and are also a staple of the fast-food industry. Unfortunately, deep frying is not exactly the healthiest cooking method, particularly when done on an industrial scale. But deep frying at home certainly does not have to be unhealthy.
Olive Oil Benefits
Fats may be saturated, polyunsaturated or monounsaturated. Saturated fats contribute to high cholesterol and clogged arteries. Monounsaturated fats such as olive oil and avocados, and polyunsaturated fats such as corn and canola oil, don't clog arteries and even may help lower cholesterol. Olive oil makes a healthier substitute for butter for dipping bread or brushing on streaks and vegetables. Olive oil is an important part of the diet eaten by people in countries around the Mediterranean Sea. These people have lower levels of heart disease than people in other countries. Adding olive oil to your diet, especially to replace saturated fats such as butter, can help lower your cholesterol.
Deep-Frying Basics
Deep frying involves heating large quantities of oil to a high temperature and then frying foods quickly in the hot oil. The key to healthier fried foods lies in the temperature of the oil. If the oil isn't hot enough to cook the food quickly, the food absorbs excess oil and fat. If the oil is too hot, components in the oil begin to break down, which produces off flavors and can produce toxic compounds in the oil. Heat the oil to the right temperature, usually 350 to 375 degrees Fahrenheit, and the food will absorb little excess oil.
Frying with Olive Oil
Every oil has a temperature at which it begins to break down. This temperature, known as the smoke point, is lower for olive oil than for other types of oil used from frying, such as peanut or canola oil. Extra virgin olive oil has a smoke point of only 320 degrees Fahrenheit, making it unsuitable for deep frying. Light olive oil, with a smoke point of 460 degrees Fahrenheit, can be used to deep fry, but deep frying with olive oil does not make food healthier than frying with other kinds of polyunsaturated oils.
Oil and Health
Olive oil can be part of a healthy diet, which may include some fried foods. Instead of deep frying, brush vegetables with a light coating of oil and cook them in the oven for oven-fried foods. Use olive oil instead of butter to flavor steamed vegetables or as a dip for bread instead of butter. Make your own healthier salad dressings with olive oil and lemon juice or vinegar. When deep frying, maintain the proper temperature and choose oils with a high smoke point.
The community responded in a grease-filled oil-off:
*Common consensus landed on peanut oil due to its neutral taste and high smoking point.
*Pierino voted for grapeseed and canola -- not without a challenge by ChefOno, who noted that grapeseed oil possesses potentially unhealthy omega-6 fatty acids, and that canola oil stinks like an old fish when heated.
*Kristen W. threw a curveball and suggested rice bran oil.
*For those of you still overwhelmed by the oil debate, Greenstuff contributed a helpful oil comparison chart with more oils than you ever knew existed.
Four Oils for Frying:
When frying dozens of donuts in the savear test kitchen, we gave serious thought to the oils we were using.
*Canola
was our go-to oil for its neutral flavor, good value, and high smoke point the temperature at which the fat starts to break down. It worked equally well for cake, yeast, and extruded donuts such as crullers. There are other fats, however, that are suitable for deep-frying, and we tested a few.
*Vegetable shortening
and lard are both saturated fats that stay solid at room temperature. We loved frying our yeast-raised donuts in them; they acquired an especially crisp skin in the shortening and a savory flavor from the lard. Most striking was how much faster these fats rose to temperature and rebounded between batches than any of the others. The remaining oils we tried had smoke points comparable to that of canola oil, but each created slightly different results.
*Peanut oil
imparted the darkest color of the bunch, giving the donuts a slightly nutty taste that we found complementary to the sweetness of the confections.
*Safflower oil
was the most like canola, frying greaseless donuts at a slightly longer cook time with the cleanest flavor of them all.
How Many Times Can I Re-use Fry Oil?
I wanted to ask you today about reusing deep-fry oil. How many times can you keep reusing it until it goes bad? I remember you writing in your Wok Skills post that you can reuse oil until it becomes dark and somewhat bubbly. However, a popular Japanese TV show reported that a katsu made with old oil tasted superior to katsu made with new oil. I also read that many tempura places use a mix of old oil and new oil, which people claim adds a bit more flavor and color in comparison to using solely new oil.
There's some good news, then some bad news, then more good news again, in that order.
Good News A:
You don't have to throw out used oil. Often you can reuse it many, many times!
Bad News:
There's no hard and fast rule for how many time you can reuse that oil. Distrust any source that gives a firm answer on the number times you can reuse oil, including this site.
Good News B:
It's easy to tell when you'll need to replace your oil, and more importantly, there are some great steps you can take to increase the useful lifespan of your oil!
Let's take a quick look at how deep-frying works before we go on.
Deep Frying Basics
Deep frying accomplishes two goals. First and foremost, it dehydrates foods. As soon as the food hits the hot oil, it begins to bubble. These bubbles are pockets of water that are suddenly vaporizing and jumping out of the food, heading up through the oil, and escaping into the atmosphere. The hotter you fry, the more vigorously these bubbles jump out, and the faster your food becomes crisp.
At the same time, the Maillard reaction is occuring: proteins and carbohydrates are breaking down and recombining to produce the browned colors and flavors that we associate with well-fried foods.
In order to prevent foods from becoming tough and stringy as they fry, most often fried foods are first coated with a protective insulative layer of batter or breading. This gives us the best of both worlds: tender, steamed food in the middle with a crisp, browned, bubbly layer of crispness on the exterior.
Incidentally, the folk wisdom that oil that's too cool will cause foods to absorb more oil is bunk. In fact, because oil tends to move into spaces that were formerly occupied by water, the amount of oil a piece of fried food absorbs is directly related to the amount of moisture that is driven off, which in turn is directly related to the temperature you cook at, and the temperature to which you cook your food to. The hotter you fry, the more oil food will absorb.
The perception of greasiness is what increases with lower frying temperatures. Why? Because soggy fried foods that contain a mixture of oil and leftover water in their crust taste soft and greasy on the palate, even though the actual amount of oil they contain is lower than that of properly fried food.
What About Oil Freshness?
Does oil freshness really affect its ability to fry, and if so, how and why?
Oil's freshness largely affects its hydrophobic nature. We all know that oil and water don't want to mix, and this is one of the reasons deep frying works so effectively. You can submerge a piece of food in a pot of hot oil and not much oil will get absorbed at least, not until enough moisture has been driven out of the food.
The more oil breaks down, the less hydrophobic it becomes. At first, this can actually be an advantage. Less hydrophobic molecules in your oil means that it can come into closer contact with foods, allowing them to fry just a bit more efficiently. This is where the wisdom of those tempura chefs comes in adding a bit of degraded, old fry oil to the new batch will improve it.
Eventually, as this breakdown continues, your oil becomes less and less hydrophobic, and eventually it'll start entering your food too rapidly, causing it to turn greasy and ruining its crispness.
At this stage, your oil needs to be replaced. Some telltale signs of old oil is foam on the top surface, an inability to reach frying temperatures without smoking, and a dark, dirty look and musty, fishy aroma.
The rate at which your oil will reach this stage depends on a number of factors. Let's talk about those.
Three Ways to Increase the Lifespan of Your Oil:
*Use a Thermometer! Overheating oil is a quick and easy way to get it to break down into unusable form. At the same time, under heating oil before adding food to it will increase the amount of time that food has to sit there, which in turn increases the amount of particulate matter that falls off of it, which again can decrease oil lifespan.
*Work Clean! Keep a fine mesh strainer by your pot as you fry foods and use it to periodically clean up your oil by picking up and discarding any bits of batter or breading that may have fallen off your food.
*Stick with Battered foods or Bare Vegetables. Battered foods will impart far fewer impurities to the oil than breaded or flour-dredged foods. Bare foods like french fries or sweet potato fries even less.
Of course, even with all these tips, there are a crazy number of variables out there that can affect your oil. Your best bet for knowing when to toss the oil and when to reuse it is your own senses. Is it foamy? Does it smell rancid? Ditch it. Otherwise, just strain, store, and you're good to go for the next fry-up.
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