Steam-boiled or microwave-zapped? Skin or no skin? For anyone still wondering how to get the most nutrition from potatoes, government scientists have crunched data for guidance.
Potatoes microwaved with skins intact retain up to 12 times more vitamin C than peeled potatoes, the scientists at the Central Potato Research Institute (CPRI), Shimla, have noted in a new study aimed at helping consumers maximise nutrition from this household staple.
Colours matter too. The researchers have found that yellow-fleshed, purple and red potatoes retain the highest concentrations of antioxidants — a set of biochemicals that can help protect biological tissues from oxidative damage — even after steam boiling.
“For maximum nutrition, it’s best to cook potatoes under dry heat — in an oven, even a traditional oven or a chulla, or the microwave,” said Bandana Kaundal, a scientist at the CPRI regional station in Meerut and the study’s lead author. Its findings were published on Monday in Current Science, a journal of the Indian Academy of Sciences.
Multiple earlier studies have established that potatoes with their skin provide significantly higher amounts of fibre, potassium and vitamin C, among other nutrients, compared to potatoes cooked without the skin.
Previous studies have also shown that steaming and microwaving are the best ways to retain nutrients, but direct head-to-head comparisons between the two methods for Indian potato varieties had been lacking — until now.
Kaundal, supervised by Brajesh Singh, a plant physiologist and director at CPRI, and colleagues analysed concentrations of three classes of antioxidants — carotenoids, phenols and ascorbic acid (vitamin C) — in seven potato varieties, either steamed or microwaved.
The researchers steam-boiled the potatoes by immersing them in a stainless steel pot filled with cool water and cooked over a consistent high temperature for 8 to 10 minutes. They microwaved the potatoes by wrapping each potato with a moistened paper towel and heating for four to five minutes.
Among the varieties examined were Kufri Mohan and Kufri Surya (both white-fleshed), Kufri Pukhraj (yellow), Kufri Neelkanth (purple) and Kufri Lohit (red).
With skins intact, steamed potatoes had three-fold to eight-fold higher vitamin C levels than peeled ones. Microwaved potatoes retained up to 12 times more.
Microwaving not only preserved carotenoids best but also retained more vitamin C than steaming — making it the more effective method in this study. Yellow-fleshed potatoes showed the highest phenol levels across both cooking methods. On average, the microwaved potatoes had the most phenols, while steam-cooked ones had the least.
Potatoes naturally contain phytochemicals — including carotenoids, phenols and anthocyanins — long associated with antioxidant and anti-inflammatory properties. Carotenoids give potatoes their yellow tint; anthocyanins, found in purple and red varieties, are another class of antioxidants linked to health benefits.
“In general, coloured potato varieties — whether yellow, purple, or red — are nutritionally superior to white potatoes,” Kaundal said.
The findings align with international studies that have also underscored potatoes’ potential as a nutrient-rich and low-fat food.
A 2013 US study suggested that a medium-sized (150 gram) skin-on potato provides more potassium (620mg) than a banana (450mg), nearly half the daily requirement for vitamin C (45 per cent), and contains no fat, sodium, or cholesterol.