Without doubts, I have also been bothered by this scenario each time I find myself in the kitchen to cook Yam. It was always dissatisfying noticing the discolouration that suddenly happens under my very eyes within seconds (they turn yellow, brown and sometimes black). Yam had been a major staple for centuries providing energy and other nutrients for the African people and beyond.
With its more than 600 documented species; edible and inedible, it remains a difficult task to identify which one would turn yellow, dotted green, brown or black during peeling.
Popular species of yam include Dioscorea alata (Water yam), Dioscorea rotundata (White Yam) and Dioscorea bulbifera (Aerial Yam). Many mothers and women have been forced to opt for other tubers or avoid yam in their diet because of this sudden reaction. Before writing this piece, I took the time to carry out a simple finding by speaking with mummies and grand mummies on the best ways to avoid discolouration of Yam during preparation and all the women gave their opinions about it. Quickly let’s check some of their advice.
Advice: Preventing Yam From Changing Colour While Peeling, Cutting
1. A few of the women said the best way to avoid yam discolouration during peeling is to “shine your eye well” when buying. They insisted some Yam types are naturally coloured and so there is nothing you can do to avoid obtaining a coloured yam. An example is a yellow yam with botanical name Dioscorea cayenensis which is a result of carotenoid in it. Try to peel the yam slightly with your finger and see if any discolouration quickly occurred when you are still at the market. If it does do not buy the Yam. It is best to buy only white yam.
2. The common one that more than 70% of them subscribed to is peeling the yam and submerging quickly underwater immediately. Some of them said they go further to peel the Yams beneath the water. I am aware that once yam is peeled and exposed to air, it is bound to undergo oxidation which causes discolouration. This, however, depends on the specie of the yam as some species do not change colour rapidly on exposure to air. White Yam remain same after exposure to hear
3. Some of the women then insisted that over the years they do not bother keeping their yams in store to be prepared when they want to eat it. They went further to say that once they had purchased the Yams, on getting home; they slice and peel off the entire yam tubers, quickly cut them into sizable portions under water, place them in a plastic container and keep them in the refrigerator to be picked whenever needed. They said keeping Yam tubers on bare floors and staying longer period before consumption may affect their colouration when peeled. Those fresh yams do not discolour like others that have stayed longer periods in storage. There is no scientific proof to this but if you do not mind, give it a try, it does not hurt.
When you look at the second opinion scientifically, I would opine that it really makes sense and it’s something I have tried myself too – it works but not 100% most times. There are times that the discolouration would just be mild but remains white at other times.
Yams contain enzymes that, on exposure to atmospheric oxygen react to give a brown colouration. When you immediately put yam underwater after peeling, you minimize the exposure time for this reaction. I have used warm water with great success.
You may want to ask, “What is different with warm water?” Let me tell you how using warm water has a place in science – oxygen dissolves in water and the amount of dissolved oxygen that the water can hold depends on the temperature and salinity of the water (how much salt there in the water). Coldwater can hold more dissolved oxygen than warm water and freshwater can hold more dissolved oxygen than saltwater.
I am certain a reasonable number of you would have other methods you practice to avoid yam discolouration. Do not hesitate to share those ideas. Thank you!
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