Natural Sweetness: Japanese Sweet Potatoes

It's hard for me to believe that these contorted "lumps" are related to delicate morning glories, but it is true. Sweet potatoes, Ipomoea batatas, are in the same family as morning glories. Since I have mostly known sweet potatoes through the grocery store, I had to discover from photographs how their flowers looked, and I was amazed at how much they looked like those of the morning glories in my garden! like those of morning glories. They have wonderful delicate leaves also. You can see a sweet potato bloom below and a morning glory bloom below that. Also, notice how similar the leaves are between the two plants! 


Sweet potatoes have a long history of providing nourishment for people. An 8000 year old wild form was found in a cave in Peru. They were probably domesticated first between Venezuela and the Yucatan Peninsula and evidence of their domestication in Peru about 2500 BCE exists. By the time Columbus landed on Caribbean Islands, sweet potatoes were common food. Columbus liked them so much that he took some back to England. 

 Although sweet potatoes originated in the Americas, they were being eaten in Polynesia as early as 1200 AD. When Captain Cook first reached New Zealand in 1769, sweet potatoes were the primary food of the Maoris.

The tropical tuber was spread around the world quickly by the Spanish and Portuguese. Today, more sweet potatoes are consumed in China than in all of the Americas.

The sweetness of most sweet potatoes is produced when an enzyme breaks starch molecules apart during heating. This produces the sugar called maltose which is made up of two glucose molecules and which is about a third as sweet as table sugar. Slow baking gives the enzyme more time to break up the starch. The enzyme is most effective between135 and 170 degrees Fahrenheit (57-75 degrees Celsius).

Sweet potatoes are an excellent source of antioxidants and vitamin A. You can find a full discussion of nutritional benefits of sweet potatoes at the Whole Foods Website.

So I took some of the Japanese sweet potatoes (the red ones in the picture at the top) and heated them, then sliced them and sauteed them in butter.  Many varieties of sweet potatoes exist, and I had never tried this variety. I'm not sure whether they are naturally incredibly sweet or the way they were prepared made them so sweet, but I ended up with something that was quite sweet without adding sugar or any other sweet flavoring. These were delicious morsels, and generally sweet potatoes are not really expensive...so they are a treat that doesn't bend the budget! You can see my results below.