Normally, fresh chunks of apple frozen in ice cream are as hard as a rock. But if you infuse them with a sugar solution, they remain soft and tasty. This sugar solution acts like a kind of anti-freeze because it has a lower freezing point than the apple (see graph below for the explanation).
This I'ble will show you how to achieve this. You will end with a subtle ice cream: at first you just taste the cinnamon, but once you bite trough a piece of apple, it's like suddenly a second flavor is released (apple).
The fastest way of infusing this sugar solution into apple is by using a vacuum chamber (look here for my previous Instructable).
However, in the case of apple, there's a secret: you don't need vacuum, just a little bit more time!
Note
It took me quite some time & effort to get this recipe right. I froze many batches of infused apple in which I varied: vacuum pressure, infusion temperature, time, sugar concentration and chunk size.
By coincidence I discovered that a reference sample that was merely soaked for a long period (without vacuum) showed nice results. It should be noted that this is true for apple. For more details on the process, see step 2 of this I'ble.
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Signing UpStep 1: Why can it work without vacuum?
If you're only interested in the recipe just skip this section.
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Roughly one could say that the capillary force infuses the liquid through the pore space of the apple, osmosis runs through the matrix of the apple.
Vacuum will speed up the capillary impregnation by removing the air in the apple and allowing the sugar solution to infuse into the pore space. As a result the contact area increases and osmotic impregnation will speed up as well.
Given enough time, any fruit can be saturated with a sugar solution without the use of vacuum. However, fruit with a softer texture (like strawberry) tends to become really weak when it is soaked in a sugar solution for a long period of time. The end result is no-where near the original fruit and tends to be jelly-like (similar to strawberries in jam). By using a vacuum chamber, this exposure time can be reduced.
Apple has a firm texture that, even after a couple of hours of soaking, remains fairly firm and close to the original. Therefore, apple is a good fruit to infuse without a vacuum chamber (provided you have time because the proces takes longer).
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I think it needs more cinnamon. Next time I'm going to add a tablespoon of cinnamon extract as well as the cinnamon sticks.
I added the cream way too early because I didn't see it in the instructions until my fifth read through. But I cooked the milk, egg, sugar, cream solution very slowly to the 80C and it never separated.
Put it in the freezer to harden for about 6 hours. Firmed up quite nicely.
Thank you.
Soaking for 12 hours should be more than sufficient. What was the size of your chunks? That may have had some influence.
I don't have the experience with apple turning green. Maybe that's something to do with Granny (I have used Elstar).
Adding more Cinnamon is a matter of taste, and you know, you can't argue about that! ;-)
Are you using an ice machine or have you whipped the cream and froze it?
Used my ice cream machine for the first time. The tub had been sitting in my freezer for a few years (I had gotten it on sale for $15 and just never found the time to actually use it.) Poured in the custard and let it churn for 20 minutes then poured in the apple chunks then let it churn again until the motor stalled. Scraped the ice cream in to a plastic tub, tucked that in the freezer until after supper.
Do you know when the green color appeared (because I have never soaked for more than 4 hours).
The apples turned green in the ice cream. They were white in the sugar syrup.
Did it look scary or was it somehow cool?
If you choose to use plain sugar instead of brown sugar, you'll get green chunks in white ice. Something for Halloween?
Same with apple. If you eat the chunks unfrozen, they're quite sweet. In the ice cream they're good.
I must admit, I have used Elstar apple (not sweet either) and the typical Elstar taste is somewhat lost but I'm not sure if that's the temperature or the infused sugar. One thing is sure though, it REALLY tastes like apple.