Soyoung Lim, doctoral student in human nutrition, Manhattan, along with George Wang, associate professor of human nutrition at K-State, stated that the color purple is caused by anthocyanin, a chemical which lowers the risk of cancer
and could even slow down certain other types of the diseases.
According to Lim, although anthocyanin has been epidemiologically associated with a reduced cancer risk, the anti-cancer properties of the purple sweet potato are still uncertain.
Lim used a sweet potato with a very pronounced purple flesh and skin that was developed by K-State's Ted Carey, professor of horticulture at K-State's John C. Pair Horticultural Center in Haysville.
"Sometimes we can find purple sweet potatoes in the grocery store but they don't have this purple color on the skin and inside," said Lim.
The analysis of three different potatoes
For the purpose of the analysis, the researchers used three different purple sweet potatoes that had different amounts of anthocyanin. To measure the amount of anthocynin in each potato, Lim extracted pigments from the potatoes and injected them into an HPLC-MS Analysis, a method used to separate components.
On the basis of the pigmentation of the flesh and fiber contents, the potatoes were separated by several traits. The analysis showed that the Kansas-bred potatoes had considerably higher amounts of anthocyanin as opposed to other potatoes.
Health benefits of anthocyanin
The researchers also found two derivatives of anthocyanin that were dominant, namely cyanidin and peonidin. They tested the two derivatives on human colon cancer cells and found that they significantly inhibited the malignant growth but demonstrated no significant changes in cell cycle.
The experts also calculated the total phenolic content of the potatoes. Phenols are chemical compounds that have anti-aging and antioxidant components. Lim disclosed that when compared with the regular purple sweet potatoes the specially bred purple sweet potato had a much higher total phenolic content and antioxidant capacity.
Besides the potential benefits, the food even appears to taste good. “It's kind of sweeter than normal sweet potatoes. We have always promoted it because we know it's a health food,” said Dr Weiqun Wang, who helped carry out the tests.
Lim stated that an in depth study of the Kansas-bred sweet potato’s underlying mechanisms could provide an insight into its health benefits.
The findings of the research were presented at the Experimental Biology Meeting held in New Orleans.
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