The Blanching Highlights
You've probably read the directions in many different recipes.
"Plunge into rapidly boiling water for one minute. Then, remove and plunge into ice water to stop the cooking process." - that's Blanching.
Learning how to blanch foods is an essential technique for home cooks. Blanching is a two-step process in which foods are plunged into boiling water, usually for only a minute or two, and then put into ice water to rapidly stop the cooking process.
You can also blanch in fat, but this technique differs from what I discuss in this article.
Reasons to blanch:
- to loosen thin skins from fruits and vegetables
- to brighten and fix the color
- to achieve a "crisp-tender" texture
- to parboil vegetables for mise en place
- to prepare fruits and vegetables for long-term freezer storage
How to blanch:
- Prepare an ice bath: put water and ice into a large bowl or a clean sink.
- Heat a large pot of water to a rolling boil, about 1 gallon per pound of food to be blanched.
- Add salt to the water; the water should be very salty.
- Immerse the food in the boiling water for the specified amount of time.
- Remove food and place it in the ice bath to cool food quickly.
- Once cool, remove food from the ice bath and pat dry.
A Note About Salt
Blanching water should be very salty. Some say, "ten times saltier than ocean water." Of course, that is a lot of salt, but there are several good reasons for salting your blanching water well. First of all, salty water is denser than unsalted water--it's why we're so much more buoyant at the beach.
The salty water on the outside of the food is denser than the water inside, so it helps prevent nutrients from leaching out of the food into the water. But, of course, after a certain point, nutrients will leach out. But, since blanching is such a quick cooking technique, it is of little concern.
Another good reason to use well-salted water is that salt helps keep green vegetables greener. Again, since blanching is a quick process, it takes little time for vegetables to go from bright green to olive drab--maybe just 2-3 minutes--so using very well-salted water helps ensure your vegetables stay nice and green.
There is a scientific reason for this concerning the magnesium at the heart of chlorophyll molecules. Suffice it to say that salting your blanching water helps keep the magnesium in the chlorophyll where it belongs, keeping things nice and green.
A third, though arguably less critical, reason to use very salty water for blanching is that, since the process is so short, the food needs more time to absorb much flavor. Therefore, over-salting the water (seasoning-wise) allows more salt to flavor the food briefly.
So, how much salt should you add to your blanching water? It's a personal preference, but start with one tablespoon of salt per gallon of water and then go from there.
Blanching Foods: In Depth
Blanching is one of those techniques that home cooks do not often employ, but it is helpful to know. It is easy to do, doesn't take much time, and can make life in the kitchen easier.
For example, have you ever tried to peel a fresh peach? It's an exercise in patience if not futility—ditto for tomatoes, nectarines, and cipollini onions.
Using blanching to par-cook is also a great restaurant time-saving trick. Can you imagine cooking raw vegetables for, say, ten minutes for every order?
With multiple orders, a cook could easily find himself "in the weeds" if they don't incorporate blanching as part of their mise en place.
If the cook blanches vegetables for 6-7 minutes, bringing them close to done, a simple 3-4 minute reheat will bring the food to done, saving the cook a lot of time (and keeping the customers happy).
One of the most critical uses for blanching is as a step before freezing or canning. In the case of food preservation, blanching does two things.
First, it can kill any little microorganisms contaminating your fruits or vegetables. Second, blanching can kill the enzymes naturally present in the food.
These enzymes are responsible for ripening and eventually browning and spoilage. These enzymes can remain active even when frozen, so for long-term storage, it is essential to kill them to keep the food as fresh as possible.
Cut the food in whatever size you like, blanch until the color intensifies, and then shock in ice water. Once cool, spread the food, dry it thoroughly, and freeze it in heavy-duty freezer bags.
Now that we know what to blanch and why we blanch, let's review the technique, which is identical for every food you will ever have to blanch. The only differences will be in the time you leave the food in the boiling water and whether you cut it or leave it whole.
How to Blanch Foods Properly
To blanch, you will need a large pot full of water. Please bring it to a boil with the lid on. Leaving the lid on will diminish the time for the water to boil.
While the water is coming to a boil, fill a large bowl or a sanitized large sink with ice water. You will also need a large strainer and an area covered with lint-free towels to dry the food after blanching.
The trick with blanching is to keep the water at a rolling boil, even when you add the food. So, it stands to reason that you can only blanch small amounts of food at a time if you don't have a huge pot. Here is the procedure.
- Once the water has come to a rolling boil, add the fruit or vegetables and let boil as long as necessary. This will depend on why you are blanching and could take anywhere from 45 seconds to several minutes. Consult your recipe if you need more clarification.
- Remove the food from the boiling water with the strainer and immediately place it in the ice water. Stir the food around to chill it quickly.
- Repeat steps one and two until all the food has been blanched.
- Use the strainer to remove the chilled food from the ice water. Drain and dry on lint-free towels.
How Blanching Makes It Easier to Peel Thin-Skinned Fruits and Vegetables
When you boil any fruit or vegetable, it cooks from the outside (the part closest to the boiling water). So, putting fruits or vegetables in boiling water for just a minute or two before putting them into ice water allows the very outer part of the fruit, the part under the skin, to become soft.
Once that happens, it becomes straightforward to peel the thin skins off of these fruits and vegetables; the skin will easily pull away from the very thin and very soft cooked layer.
To make it even easier to peel, use a sharp knife to cut an X in the bottoms of the food you are blanching: peaches, nectarines, apricots, tomatoes, cipollini, or pearl onions. Then, once you have stopped the cooking process in the ice bath, use a sharp paring knife to pull up the edges of the skin where you made the X and peel away.
How Blanching Brightens and Fixes Color
When we talk about brightening and fixing color, we're talking about the color green in vegetables like broccoli, spinach, kale, green beans, peas, etc. Have you ever noticed that orange carrots and peppers are bright orange, red peppers are bright red, and yellow peppers are bright yellow, but green vegetables are dull-looking?
That's because, even though the green of the chlorophyll in those plants provides the green color, small air pockets cloud the color. A quick plunge into boiling water bursts some outer cell walls, allowing the air to escape and letting the true bright green of the chlorophyll shine through.
If you've boiled green vegetables too long, you know they turn from a bright, vibrant green to a dull olive green. To prevent this from happening, remove the food you are blanching to an ice bath when it is still bright green. For tender greens like basil or spinach, this can be as little as 30 seconds.
For more substantial green vegetables such as peppers, broccoli, or green beans, expect to blanch for up to two to three minutes. The main thing to remember is not to walk away and to shock them in ice water as soon as they are a lovely bright green.
Blanching not only brightens but also fixes the color. This means blanched vegetables do not turn brown over time like raw vegetables. All fruits and vegetables contain enzymes that, if left unchecked, break down the foods into a brown, slimy mess.
Raising the temperature of the food to over 120°-140°F (depending on the enzyme) essentially denatures or turns off the enzymes so that the food does not brown.
What Is An Ice Bath?
After blanching, vegetables are often placed in an ice bath or bowl filled with water and ice to stop them from continuing to cook and preserve their color. This is also called "shocking" the vegetables. Once you have cooled down the ingredients in an ice bath, remove them immediately so they don't get waterlogged.
How Blanching Helps You Achieve a Crisp-Tender Texture
While tender raw vegetables such as spinach, arugula, and other herbs and lettuce do not need to be cooked to be enjoyed, denser vegetables can benefit from a short blanch, even if they are to be served cold. Take the time to blanch green beans, broccoli, cauliflower, peppers, or other vegetables before adding them to a cold salad or crudités platter. You will notice that the blanched vegetables are sweeter and have a pleasing "crisp-tender" texture.
Your blanched vegetables will be sweeter because some cell walls will rupture, releasing sugars and other flavor compounds. They will be crisp-tender because the outer part of the vegetables will be tender from being cooked while the interior is still crisp and raw-tasting. Crisp-tender is to vegetables what al dente is to pasta.
While it takes longer to achieve crisp-tender than to blanch to peel, generally speaking, a vegetable will be crisp tender-at about the same time it becomes a beautiful bright green color. For vegetables that are not green, such as cauliflower, allow 2-3 minutes.
The best test for crisp-tender is tasting, so do not hesitate to remove taste during the cooking process and remove the food to an ice bath when you are happy with the texture.
How Blanching Foods Helps with Your Mise en Place
This reason for blanching is similar to blanching to achieve a crisp-tender texture but assumes that the food will be further cooked later. It is almost exclusively used in restaurant kitchens but is an excellent learning technique for home cooks. For example, say there is a dish that has boiled potatoes as a side. The dish takes 7 minutes to cook, but the potatoes take 12 minutes.
Ideally, the main and the side should both be ready at the same time. An easy way to ensure this is to blanch or parboil the potatoes in boiling water for 5 minutes and then shock them to stop cooking.
Then, when someone orders that dish, each component will be ready in 7 minutes. Blanching is only called parboiling when foods will be further cooked later. Otherwise, it is precisely the same technique.
How often will you have to use this technique at home? Probably not very often, but it is a valuable technique to have in your arsenal for holiday gatherings or dinner parties where it pays to get as much prep out of the way as possible, so you don't find yourself chained to the stove when your guests arrive.
You should experiment with blanching to see if it helps save a little time.
See String Beans with Sauteed Tomatoes & Garlic. This technique can be helpful if you make a lot of stir fry. Before you stir fry, blanch cut-up firm vegetables such as carrots, cauliflower, and broccoli for 2-3 minutes and then shock in cold water.
When it's time to stir fry, you can put all the tender and firm vegetables into the wok or stir fry pan simultaneously instead of adding the firmer vegetables first. This simplifies the cooking process and helps you get dinner on the table much faster, especially if you did the blanching a day or two beforehand and refrigerated your vegetables.
How to Blanch Foods to Prepare Foods for Freezing
As mentioned above, blanching can turn off enzymatic activity and prevent browning. This is particularly important in freezing fresh fruits and vegetables because enzymes still function at freezer temperatures. Unfortunately, this means that, over time, your lovely summer peaches will turn brown, even after you have "safely" frozen them.
Blanching foods for freezing is the same as any other blanching. If necessary, cut the food to a uniform shape and submerge food in batches into vigorously boiling water for about 2 minutes - enough time to denature the enzymes.
Remove the food to an ice bath to stop the cooking process. Next, dry the food thoroughly and freeze it in a single layer on a parchment-lined baking sheet. Once the food is frozen, you can store it in freezer bags or other containers. However, the cell walls of fruits and vegetables will be damaged by ice crystal formation in the freezer. Because of this, once thawed, most fruits and vegetables will become soggy and are best suited to stews and soups (in the case of vegetables) and pies or muffins (in the case of fruits).
The faster you can freeze food, the smaller the ice crystals and the less damage to cell walls. Freezing foods in a single layer can minimize damage to the cell walls, but home freezers do not freeze foods quickly enough to eliminate damage.
How and Why to Blanch Foods in Fat
Fat blanching is very different from boiling water blanching. While water blanching is used for many purposes, fat blanching is a method to partially cook a dense vegetable without browning it. The only case of fat blanching I know of is making delicious French fries.
The secret is a two-stage frying method. The first stage - the blanch - happens at a lower temperature to cook the potato all the way through, while the second fry happens at a higher temperature and provides a deep golden-brown color.
To make great fries, cut and dry your potatoes well. Blanch them for 4-5 minutes in oil, which is about 325F. Remove to paper towels. At this point, you can finish cooking them later or continue.
Heat the same oil to about 370°F and fry for an additional 2-3 minutes until deeply golden brown. Drain and add salt and any additional seasonings.
This technique can also be employed when frying any dense vegetable, such as sweet potatoes, parsnips,s or even turnips.
How Long Does It Take To Blanch Foods?
One of the most underrated cooking techniques is blanching. A 2-step process where you plunge ingredients into boiling water and immediately stop the cooking by giving them a cold bath.
Chefs and home cooks use blanching for various reasons, including peeling fruits and vegetables, brightening food colors, preparing for freezing, and preparing for mise en place.
The numbers below represent times for water blanching. There are other blanching methods using steamers and microwave ovens, but I prefer boiling water.
It's also important to note that it is essential to blanch at a rolling boil, so if you are blanching in batches, ensure you bring the water back to a rolling boil before adding new ingredients.
Lastly, these blanching times come from various sources like the National Center for Home Food Preservation and the University of Minnesota. Still, none of these sites offer amounts to go with the times.
It makes sense, though; the more stalks of asparagus you add to the pot, the time should take longer than if you just blanched one item.
So you can use these times as guidelines and note your experiences for future blanching.
Vegetable & Fruit Blanching Times
|Blanching time in minutes
|Artichoke – Jerusalem
|3 to 5
|Asparagus – small stalk
|Asparagus – medium stalk
|Asparagus – large stalk
|Beans – snap, green, or wax
|Beans – lima, butter, or pinto - small
|Beans – lima, butter, or pinto - medium
|Beans – lima, butter, or pinto - large
|Broccoli (flowerets 1 ½ inches across)
|Brussels sprouts – small heads
|Brussels sprouts – medium heads
|Brussels sprouts – large heads
|Cabbage or Chinese cabbage – shredded
|Cabbage or Chinese cabbage – wedges
|Carrots – small, whole
|Carrots – diced, sliced, or lengthwise strips
|Cauliflower (flowerets, 1 inch across)
|Corn-on-the-cob – small ears
|Corn-on-the-cob – medium ears
|Corn-on-the-cob – large ears
|Greens – collards
|Greens – all other
|Kohlrabi – whole
|Kohlrabi – cubes
|Okra – small pods
|Okra – large pods
|Onions (blanch until center is heated)
|3 to 7
|10 to 15 seconds
|Peas – edible pod
|2 to 3
|Peas – green
|1 ½ - 2 ½
|Peppers, sweet – halves
|Peppers, sweet – strips, or rings
|3 to 5
|Soybeans – green
|Squash – Summer
Fruit Blanching Times
|Tomato (for peeling)
|Apples (for peeling)
|Peaches (for peeling)
|Pears (for peeling)
Now that you are more familiar with blanching, I hope you can see its time-saving and money-saving possibilities. For example, par-cooking some of your vegetables for a Thanksgiving or Christmas meal might make your life easier.
Blanching some broccoli or green beans for a salad makes them vibrant green, but it might eliminate some of those enzymes that make some of these cruciferous vegetables hard for some of us to digest.
Blanching before freezing can help prevent your bumper crop of cauliflower from going bad, even in the deep freeze.
And, for those of you who have made a right mess of a peach when trying to peel it, myself included, blanching can be the technique that turns the idea of making a fresh peach cobbler from "No way!" to "A Walk in the Park."
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