Wednesday, January 5, 2011

A Rose is a Rose...

According to Shakespeare, a rose by any other name would smell as sweet.  Unfortunately, that doesn’t mean that a food by any other name is still that food.  

Case in point: several years ago my mother was diagnosed as allergic to sweet potato but not to yam.  These are, biologically, very different foods, and generally differ in taste, texture, and sometimes appearance.  Yams are from the Dioscoreaceae (Yam) family and are closely related to lilies and grasses, whereas sweet potatoes are from the Convolvulaceae (Morning Glory) family.  It would seem a simple thing for us to avoid having sweet potatoes in the house, but over the recent holidays it became apparent that Americans are in fact often confused about the difference between sweet potatoes and yams – or worse yet, think there is no difference. 

The canned yams we buy at our local supermarket for making traditional Thanksgiving and Christmas dishes, for example, actually say BOTH on the label – “yams” in BIG letters, and “sweet potatoes” in smaller letters under that!  Interestingly, this same supermarket chain sells fresh (raw) versions of these two foods but has “yams” in one place, “sweet potatoes” in another, clearly marked as different items and clearly different-looking in appearance.

Knowing that yams and sweet potatoes are not really the same thing doesn’t necessarily make choosing the “safe” one any easier when shopping.  I did some research and found the reasons that Americans are so confused – and I say “Americans” because it seems that the rest of the world already has this riddle figured out.

Long story short: what we call “yams” are actually orange-fleshed versions of what is really a sweet potato.  That means that the canned yams label is accurate when it says “sweet potatoes”, but it is not scientifically correct in calling that same product “yams”.  A “true yam” is a bland, starchy tuber that is usually much drier and more starchy than a sweet potato and contains very little beta-carotene.  What Americans think of as yams are native to the Americas and are primarily grown in the southern USA, whereas true yams are of African and Asian origin and currently come to us mostly from the Caribbean.  True yams are generally harder to find in the USA, though that is changing.  History and habit are the main reasons for our confusion and the fact that the name “yam” appears on can labels (see below), but in the manufacturers’ defense, I did discover that for a long time now the US Dept. of Agriculture has required that the label “yam” always be accompanied by “sweet potato”, indicating the true biological origin.

Historical accounts say that Americans refer to sweet potatoes as yams because the word “yam” is similar to the African words “njam”, “nyami”, and “djambi” (meaning “to eat”) and came with the first Africans brought to the New World, who thought that our sweet potatoes resembled their native yams.  The true yam (starchy, less moist tuber, not our sweet-tasting delight) is still a common food in Africa and the Caribbean, as well as in Asia and Latin America.  Another likely reason for the name confusion: when sweet potatoes (our “yams”) first became readily available in the US marketplace, our forefathers logically wanted to differentiate between the good old white potato and this new, sweeter, more colorful version.  In terms of both taste and biology, we should call the latter sweet potatoes only, which is what the rest of the world already calls them (even when they are marked here as “garnet yam” or “jewel yam”!).  Caveat: there are some sweet potatoes that have lighter-colored flesh (yellow or white) and which may be drier and less sweet than their darker cousins, but they’re still sweet potatoes, not yams.

As for yams, we Americans have simply got it backwards: the candied, marshmallow-topped dish that what we eat at Thanksgiving and Christmas should be called sweet potatoes only, never yams.  And what we see in the supermarket marked as fresh “sweet potato” (when differentiated from “yam”) is actually the “true yam” (starchy, less moist tuber) and should be called a yam only.  The flesh of true yams can range from ivory to yellow to purple, and their skins (rough and scaly) can be white, pink, or dark brown.  I personally don’t buy or cook those (they are, after all, an allergen for my mother), but in other parts of the world they are roasted, boiled, mashed, fried, ground into flour, and made into porridge, noodles, cakes, and a variety of other dishes, none of them sweet unless a sweetener is added.  Examples include Congolese fufu, Japanese ganmodoki, Chinese yam and chicken soup, Jamaican yam and goat meat appetizer, and Vietnamese creamy yam soup.
Further irony on this topic: you will sometimes see the phrase “true sweet potato” – don’t be fooled, because in America this means what we now know should be called a yam (“true yam”); nonetheless, unless you’re sure it’s a biologist speaking, be wary!  Most Americans don’t know the difference, and any foreign products made to sell in the USA could easily be trying to follow the common lingo by saying one when in their own country it might be the exact opposite J.  Thus when I saw “yam noodles” at the Japanese store near me the other day, I thought twice and didn’t buy them, realizing that in Japan a yam would really be a biological sweet potato and therefore off-limits in my house.  I’m still never sure which it is when I see “sweet potato flour” sold online, so I don’t take the chance even though I know that in other countries that seems to be what we call yam and therefore would be safe; in fact this type of flour tends to be the non-sweet type or “true yam”, in which case it is actually NOT safe for my family.

I am certain that this dichotomy is not unique to yams/sweet potatoes nor does it only confuse us Americans.  For example, I’ve mentioned in past postings that what is often commercially referred to as arrowroot can in fact derive from any number of biologically different plants found in diverse parts of the world; furthermore, this is a name sometimes applied to other foods which can also be variously known as tapioca, cassava, yucca, manioc, or mandioca.  Package labeling can only go so far in clarifying the origin and true name of food, so my advice is to err on the side of caution.  I suppose that Shakespeare is right about the rose and I would love to smell it even if it was called a tumbleweed; we food allergy sufferers just can’t afford to take that risk when it comes to foods of a different name.

1 comment:

Anonymous said...

Thank you for this. I was looking for the sweet potatoes that are known for their "anti-inflamatory" properties. Just ate the WRONG kind- true yam = white "sweet potatoe" from specialized market. Throat swelling rapidly - Will take Benadryl STAT.
Next time, I'll try the old american standby- the "orange yams"...