Yams are a very good source of potassium and fiber, as well as vitamins B1, B6, and C. In addition, yams are a good source of manganese and carbohydrates. Besides all of the reasons they are good for you, they just plain taste great...naturally sweet and full of flavor. I found a recipe for dehydrated yams, and decided it would make a wonderful backpacking meal, so I excitedly went and bought 10 pounds at the grocery store. You get some funny looks when you buy so many yams!
Next they need to be boiled or steamed for just a minute or two. This apparently is a key step because the "cellular membrane within the structure of the vegetable needs to be changed through cooking (like steaming or boiling) so that it’s softer". Skip this step and you'll end up with yams too chewy to be enjoyed. So I brought a huge pot of water to a boil, dropped all 10 pounds of yams in, replaced the cover, and left them in there for about 5 minutes. The volume was so large it really didn't return to a full boil, but I figured it would be OK since I left them in there for longer than a minute or two.
Onto the dehydrator trays the shredded (almost) boiled yams went. 145 degrees until they are crispy - about 5 or 6 hours should do the trick.
What came out was a crunchy little bag of shredded goodness - all 10 pounds fit in a gallon bag. They taste pretty good right out of the bag too!
So how did they come out once a cooked them? Chewy...too chewy to enjoy. Obviously that step where I didn't bring them back to a full boil was more important than I thought. So rather than toss them, I reboiled them, then dehydrated them again. This time when I cooked the yams they were not chewy, but I think the repeated boiling, dehydrating, boiling, and dehydrating cooked the wonderful taste right out of them. They were bland.
So this post is about what NOT to do...we all make mistakes. I'm going to try this again, and I will boil less yams at a time and make sure I bring them to a full boil. Yams are too good to give up on, so wish me luck and I'll let you know how it goes!
Update 3/06/2011: My second attempt was a great success...sooo good! As Eugene suggested below, add some butter flavoring, cinnamon, or whatever you prefer to make it even better. And a huge advantage is the fact that it ends up being extremely light. Today I started with 27 ounces of yams and after dehydrating the batch weighs scant 3.08 ounces, which translates to 281 calories per ounce. This is the most calorie dense food I have found, even higher than 257 calorie per ounce almonds! Have some of both and you end up with a great balance of carbohydrates, fat, and protein!