Obedient Ingredients

A place to put cooking ideas to the test.

Kale Chips – Aluminium Foil Test


Whomever spends this much time thinking about Kale must be a pretty cool dude.

In a previous post, I tested making kale chips using a normal baking sheet vs. parchment paper. Conclusion: The baking sheet made the chips slightly more crunchy but the parchment paper was easier to clean up. I also learned the important lesson of making sure to COMPLETELY COAT the kale leaves in my oil mixture (EVOO, balsamic vinegar, kosher salt, garlic).

After that experiment, a new question arose: would using aluminum foil make a difference?

I ask the hard hitting questions in this blog.

My test kitchen was about to find out. I wanted to test making these summer homemade chips using both the normal baking sheet and the addition of aluminum foil.

Question: When making KALE CHIPS, does using aluminum foil make a difference?


First of all, I seem to confuse aluminum foil with tin foil, as I am sure most of you do as well.

The generic foil I am using is called “Aluminum Foil”, but I am guessing that it’s OK if people refer to it as “tin foil.” If someone says to me “get the tin foil!” I will not reply with “Um, excuse me, in modern times tin foil is actually used for electronic capacitors,” while adjusting the glasses on my nose.

I give you permission to shove me in the school locker if I ever say that.

Some recipescall for the use of “tin foil” when baking kale chips, although I had to type in “tin foil kale chips” in Google to see such recipes. Harmless mistake to call it that (this post originally used the phrase “tin foil”).

Back to the aluminum foil…

One blogger specifically refers to the usage of aluminum foil and states: “Don’t be like me.  The first time, I didn’t use foil, and even though I spraying the baking sheets with cooking spray, some of the chips stuck, and they couldn’t be salvaged.  Trust me, use some foil, parchment, or silpat sheets!” 

First of all, I have never heard of silpat sheets. Sounds intimidating and I will not Google them at this moment.

Secondly, this is the point of my whole blog! To test if these things actually make a difference! Science!!

So, why is this foil used with baking? What I’ve learned so far:

+If you seal certain foods tightly in it (such as fish) it essentially steams the food, trapping in the moisture released from the heat.

+When covering certain foods, there is less direct heat on the food, meaning that the food you are baking is indeed baking, but not getting to crisp or burnt on the top of that food.

+It makes cleaning easier (but I learned NOT to line this foil at the BOTTOM of your oven. Here’s a helpful Do’s and Don’t’s with Aluminum Foil. )

I haven’t found anything that comments on what putting food ON the foil will do to the baking process, other than making clean up easier (which was similar information I found in my parchment paper research). For today’s experiment, I will need to test whether putting aluminum foil ON TOP OF the kale and ON THE BOTTOM of the kale make any differences.


On to the kale…

Kale, in my opinion, is delicious and it’s incredibly healthy. And cheap! Olive oil and (sea) salt/pepper it up, saute until reduced in size, put a few drops of balsamic on it, done: side dish for dinner.

Essentially, I will judge you harshly if you do not like kale.

But if you have a few leaves left over that will not make for a good meal’s portion (about 2-3 leaves per person…the leaves shrivel up a good amount), people like to bake them for a little snack.

Ingredients: Fresh kale, olive oil, garlic, kosher salt, balsamic vinegar
Tools: Mixing bowl, baking sheet, generic tin foil, oven

After washing and hand-cutting the kale (use everything except for the stem which runs up the middle of the leaf), I tossed the leaves in the bowl with the rest of the ingredients.

**Make sure to cover the leaves with your oil mixture thoroughly! I made the mistake of not making sure they were covered, and the chips’ crunchiness was inconsistent.**

I arranged the kale leaves in 4* different arrangements on my baking sheet:

1) Kale on baking sheet with no cover.
2) Kale on aluminum foil, no cover.
3) Kale on baking sheet covered with aluminum foil.
4) Kale on aluminum foil and covered with aluminum foil.
5) *since I had some kale leftover, I made the foil pouch and put kale in it.

I then baked the whole thing for 13 minutes in the oven at 350 degrees. (Why 13 minutes? Recipe called for 10-15 minutes; 15 minutes cause the chips to become too dry, fragile, and lose taste, and by 10 minutes I noticed the edges of the leaves became a bit brown, meaning they are ready. I aimed for the middle this time).

As I taste tested, I was looking for several things: tastecrunch and chewiness, cleaning ease and heat retention (how long do the chips stay hot). This tasting was not blind and I conducted this on my own.


Only baking sheet On foil, no cover On baking sheet, covered with foil On foil and covered with foil. Foil pouch
Taste Some bitterness, burnt taste More bitterness Good taste, no bitterness, some saltiness bitter taste, some saltiness Best taste
Crunchiness Crunchiest, fragile, incredibly dry Chewier, with some crunch Not so crunchy, but not too chewy Oily, not too much crunch, very chewy Chewiest, no crunch, oily
Heat Retention No longer than 2 minutes. No longer than 2 minutes. No longer than 2 minutes. No longer than 2 minutes. Stayed the warmest, more than 5.


 There seems to be a tricky balance with getting your kale chips to land somewhere in between very dry, brittle and potentially burnt and the texture you would get from essentially frying kale in a pan with olive oil (which is how I usually love to eat it). The more of a pouch you create, the soggier it is, so it’s not really a chip any longer, BUT some taste is retained and not completely dried out.

The foil on the top seemed to be the deciding factor with how crunchy/brittle it becomes. It depends on what you prefer in your chip: total cripy-ness yet less taste (no foil covering) or a mix between chewy and crunchy with more taste (foil covering).

The aluminum foil covering the vegetables prevent the kale from becoming too dry too quickly, but leaving them on the baking sheet allowed them to actually bake and become crispy, just like a vegetable chip should be. When it comes down to it, I do not think there is a big difference between putting foil UNDER the kale or not; the factor with more impact is the foil COVERING the vegetable.

Future tests:

I need to get some participants to help me with blind taste tests, aka I need friends.

Perhaps I will tweak the oil mixture recipe to try and get a great taste with a complete crunchy texture.

Is there a difference if you saute the kale FIRST and then you bake it??

And finally, oven temperatures and baking times. This recipe called for 350 degrees and about 13 minutes. What about 400 degrees and 4 minutes? 300 degrees and 20 minutes?

4 thoughts on “Kale Chips – Aluminium Foil Test

  1. Pingback: Kale Chips – Parchment Paper Test « The Quantitative Kitchen

  2. This is gorgeous! You are amazing, wish I can do something like that too! =)

  3. This is super helpful! The bitterness of kale chips and that powdery flatness they can get bothered me so much that I stopped making them. Foil pouch it is!

  4. To help with the bitterness, it is suggested that you massage the kale while still in big leaf form for about 2 to 3 minutes. Also, kale should be dry when baking. I saw someone using a blow dryer which really worked. Even better, use a blow dryer with an infuser and it doesn’t blow around. Again, this is in full leaf form.

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