Nutritional Aspects of Potatoes

European peasants quickly discovered that potatoes combined with some dairy products such as milk and butter gave a healthy balanced diet. The otherwise completely impoverished Irish of the 18th and 19th Centuries were nevertheless famous for their size and strength. This was due entirely to their unrelenting potato-based diet.
 
Potatoes often have good levels of quality, energy rich, starches and reasonable levels of structural proteins and amino acids. Water soluble vitamins are present in modest quantities. Potatoes are so palatable and form such an acceptable part of our diet in various forms, that most of us get the majority of our Vitamin-C intake from our potato consumption.

Food values of potatoes vary greatly depending on variety, growing conditions and geographical location. Dry matter values which measure what is left (mainly starch) when potatoes are dehydrated are useful indicators. High dry matter varieties tend to be floury in texture, high in food value, high in “old fashioned” flavour and are often more difficult to boil. The latter is because starch swells as it cooks and tends to burst cell structure. This also varies with protein content to some extent because cells with lots of protein structure resist break-up. Low dry matter, high yielding varieties are very much in the ascendancy at the moment because firm boiling potatoes have become the norm in supermarkets. Possibly the population nowadays requires less energy from its basic food supply.

High dry matter types are usually more suitable for mashing, baking, microwaving and frying. They crisp up more and absorb less fat. Medium dry matter potatoes are general purpose. Low dry matter types are better for boiling and salad use. Specialist salad varieties can boil particularly well, staying firm and not discolouring and are pleasant to eat hot or cold. They will slice or dice cleanly. They are often scab-resistant to give clean skins so that tubers can be boiled whole and unpeeled. Strong “earthy”, “floury” flavours are often associated with high dry matter potatoes. Low dry matter flavours are often described as “mild”, “fresh” or “clean”. Some classic low dry matter salad potatoes, however, manage somehow to have very strong flavours. Individual perception of potato flavour varies greatly and individual likes and dislikes also vary greatly. Potatoes of the same variety will have substantially more dry matter in the south of England than those grown in the north of Scotland. This can result in some varieties having completely different reputations in different parts of the country.

Red, blue and purple colours in some garden varieties are anthocyanins. Consumption of these is good because they are antioxidants with anticarcinogenic  properties. Green and damaged potatoes on the other hand have raised levels of glycoalkoloids which are fairly poisonous. Bitter potatoes should be rejected.

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