What's the best way to extract juice while baking sweet potatoes?
December 29, 2011 7:06 PM   Subscribe

How can I extract the maximum caramelized juice from sweet potatoes?

I have been baking sweet potatoes in the oven and noticing the yummy juice that flows out of them while baking. I want to extract even more of this juice and, without adding any sugars or sweeteners, preserve it in a jar as a sort of syrup. It seems like it could also be made into candy, because it has the viscosity of caramel.

Anyone have an idea on the best way to extract it while cooking? I usually bake them at 425, but it's tricky because as soon as the juice comes out it can cook too much and turn to ash. This doesn't happen, however, if the juice is trapped in the bottom of the tin foil. Also, I take the potato out after about 60-90 minutes because it's ready to eat. (I like them baked until very soft indeed.) Maybe if I leave them in longer I'll get more juice? Oh also, is there a way to use the stovetop instead of the oven, to possibly extract the caramalized juice (or otherwise reduce the yam into syrup)?

Lately I've been baking the yams in tinfoil (but with the top part open). After an hour or so there is some really yummy brown juice in the bottom of the foil which I eat with a spoon. And the peel is soaked with the juice. (Maybe if there were no peel, more of the juice would come out?) But I want a reliable way to extract as much of this juice as possible, before it entirely caramelizes or hardens. It's truly the nectar of the gods.

Again, I don't want to use any sort of sugar or sweetener. I would use other natural additives if needed, and if they didn't change the natural flavor by much.

Thanks in advance for any ideas.
posted by TreeHugger to Food & Drink (9 answers total) 7 users marked this as a favorite
I'd probably juice raw sweet potatoes in a juicer, then caramelize it in a pan on the stove, just like making regular caramel from sugar and water. I haven't actually tried this, so YMMWildlyV.
posted by mostlymartha at 7:16 PM on December 29, 2011

You could bake them at a much lower heat, for longer. I did one at 350 the other day, and it soaked itself when I wrapped it in foil just to store it. Foil + lower temp = liquid.
posted by Riverine at 7:56 PM on December 29, 2011

Don't have a direct answer, but if you haven't already, you might care to read this about sweetness and sweet potatoes from Serious Eats.
posted by ftm at 8:02 PM on December 29, 2011

You might be able to pressure cook them. All the juice will be trapped but diluted and not carmelized. You'd need to reduce it.
posted by chairface at 9:03 PM on December 29, 2011

cooking issues ep 24, 14:40 pt 1 has some interesting stuff about a clarified caramel. I thought there was something more closely related to baking them but I'm not seeing it. There are a couple of mentions in the notes from other shows about optimizing sugars in them and it could have come from one of those. If nothing comes up in their archive, then sending in a question might be worth while.
posted by 0bs01337 at 10:49 PM on December 29, 2011

Best answer: Raw sweet potatoes have a lot of sugar, and even more starch. Cooking them activates enzymes which convert some the starch into even more sugar. You can maximize this enzyme action - and thus the amount of tasty syrup you get - by holding the temperature in the correct range (in the case of sweet potatoes it's between 140 and 150F) for an hour. In brewing or distilling, this is called "mashing".

If you simply want sweeter potatoes and more juice, I would cook longer at a lower temp in a covered dish. This gives the enzymes more time at the sweet spot to convert the starch to sugar, and makes the resulting juice less likely to burn.

If you want to go all out and make a pot of sweet potato syrup (which sounds delicious), you'll need a meat or candy thermometer, some cheesecloth or fine strainer, and a pot or double boiler.

Start by shredding the raw sweet potatoes in a grater or food processor. Then toss them into a pot with just enough water to cover. Less water means better starch-to-sugar conversion. You want just enough so that it doesn't burn. A double boiler is helpful here, if you have one.

Slowly bring the temperature up to 150F, while stirring, then cover and turn the heat off. Check on it every 10 minutes or so for an hour. Apply heat and stir whenever the temp drops below 143F.

The liquid should be noticeably sweet, and the potato shreds should be soft. Dilute the mixture with 3-4 times its volume in water. (i.e., if you have 1 pint of shredded potatoes and water, add 3-4 more pints of water.) Move to a larger pot if necessary.

Apply heat, and raise the temperature to 170F, stirring as you go. This will stop the enzyme action, and start to free the sugars trapped in the shredded potatoes. Once you hit 170F, turn off the heat. Strain the shreds out of the liquid by pouring it through a strainer or cheesecloth.

You will now have a tasty, but dilute sweet potato syrup. You want to reduce this by half, or even 2/3rds to make a thick syrup. A double-boiler or slow-cooker is strongly recommended here. (you don't want to waste an hour-plus of work by burning it!) Go slow, and check the viscosity regularly with a metal spoon. Take a small sample and let it cool to see how thick it is at room temp.

Note that the above instructions will also work with pumpkins and most other types of squash, except that most of them don't have enough naturally-occurring enzymes to convert their own starches to sugar. To accommodate this, you need to crush up a tablet of Beano and mix it into the shreds in the "mash" step.

Let me know if you try this. You've inspired me to try making some pumpkin syrup, with chili and a touch of curry powder.
posted by Anoplura at 11:54 PM on December 29, 2011 [19 favorites]

Response by poster: Wow, such helpful info Anoplura (and 0bs01337)! Many thanks, I look forward to some good syrupy times ahead!
posted by TreeHugger at 12:02 AM on December 30, 2011

Response by poster: Anoplura: One clarification if you don't mind. Is there ever a time when I would add additional water to the pot during any of these steps, like if the level got too low from some water vaporising away? And if so which steps? Gracias.
posted by TreeHugger at 12:22 AM on December 30, 2011

"Is there ever a time when I would add additional water to the pot during any of these steps..."

No. During the hour that you are holding the mixture at 140-150F, the temp is too low for significant evaporation. You just need enough water to barely cover all of the shredded sweet potato and ensure that the heat and enzymes get distributed evenly.

You add more water in the second step (heating to 170F) in order to extract as much of the sugars/flavor from the solids as possible. After straining the solids, you should taste them. If you did everything right, they should be remarkably bland.

In the final step, you are reducing the mixture, and trying to evaporate as much of the water as possible (without burning anything), so you don't add any additional water.
posted by Anoplura at 2:21 AM on December 30, 2011

« Older What is 24 years anyway?   |   20 grand seems like a lot of money for not that... Newer »
This thread is closed to new comments.