Do alcohol and salt help in preservation of dehydrated vegetables

You get mold (and less visibly, bacteria) growth after 4-5 days because your water (humidity) content left in the deyhdrated food is greater than 5%. Typically dried apples (and other types of fiberous dried fruit) have humidity levels closer to 20% when you don't dry them to a crisp. That means the treats you make aren't shelf stable, but luckily this can be fixed with some experimentation.

Each food has it's own requirements for preservation. Here are some quick guidelines to try out on apples. For yams and bananas, I would try dehydrating them a bit more closer to being crisps.

Steps:

1. Wash fruits thoroughly before dehydrating. I don't do this, but you could try using a "fruit wash" (product for washing fruit).

2. Dehydrating isn't sterilization - the dehydrator isn't hot enough to sterilize the food, so some of these 'nasties' are left on there and waiting for their chance to grow. Commercial-grade food is always sterilized. Because a dehydrater isn't sealed well, I suggest you nuke the treats in your oven for 5-10 minutes on high heat AFTER you dehydrate the stuff, experimenting to make sure you don't dry them out too much in the oven. Also, be careful because the sugar is concentrated in dehydrated fruit, so it will burn easily. Wrapping the fruit in tin-foil before placing it in your oven is a potential trick because this effectively sterilizes the fruit in a steam bath. If you use foil, you'll need to cook them longer - start with 15 minutes.

3. After the treats are dehydrated and sterilized, try storing them in air-tight containers and always away from light in a cool/dark place. They need 7-10 days to "equilize" the moisture between each dried piece of fruit. Make sure to shake the containers every once in a while so they don't all stick together.

BEYOND THIS, there are more advanced techniques that you can easily try - including conditioning the dried fruits and a number of fruit-baths that preserve the fruits with harmless chemical solutions, like Ascorbic Acid (vitamin C). Try reading more on this link from UC Davis:

http://homeorchard.ucdavis.edu/8229.pdf

(Start Reading on Page 7).

It's been a long time since I actually did this, but my recollection is that the result will leave some residual water. It's not an ideal environment for a flambé, but that's OK because you're not actually trying to cook with it, it's more of a show technique that generates just enough heat to produce a caramel-like texture from ground-up caramelized sugar.

Some pointers that might help you here:

• Don't overdo it with the alcohol. You want to use a very small amount - just a splash.
• Make sure the alcohol is hot enough before you try to ignite it. Make sure that it is a uniform temperature, and that you're not just igniting the surface.
• Work quickly. If too much of the alcohol burns up while you're working, then you are essentially dumping water in, and there might not be enough heat to melt the sugar powder.
• Consider serving the crème brûlée closer to room temperature, or at least not as cold as fridge temperature. The colder it is, the quicker the fire will get doused and the more liquid will (probably) remain behind.
• Custards are firmer than pudding to begin with, so "watering it down" shouldn't be a huge concern.
• It's a bit of a cop-out, but I want to say, don't worry. If it's good alcohol then nobody's going to mind a bit of a film on the surface - it's part of the attraction!

I remember this taking me several tries to get right, and probably wouldn't use the technique at all if I were serving to a particularly critical audience. It's more about getting a passable crème brûlée with some cool visual effects than getting a perfect crème brûlée with an impossible technique.