POTATOES: Super Delicious But Are They Super Healthy?

Potato is one of the most used staple foods. It is the main ingredient of perhaps the most popular dish in the world – chips. But for many it has become a food to avoid with its high carb content, including diabetics and weight watchers.  Is it on the health hit list for a reason?

If the potato were a woman I would surely marry it. Any ingredient that can be turned into a chip is bound to evoke some kind of torrid love affair on my part. Too far? OK, I will stick to eating potatoes rather than engaging in some strange form of dendrophilia. When it comes to potatoes there are enough culinary delights to keep even the most bent mind occupied. Chips, crisps, fries, mash, hash browns, roasts, curries, salads, potato dauphinoise, shepherd’s pie, rösti, soups, potato skins and of course the baked potato. To mention but a few dishes.

In recent years, the potato has however, been given somewhat a bad name. With the steady march against starch by health gurus and professionals alike, the potato has fallen into disgrace. Of course this hasn’t stopped such a regal ingredient all that much. As previously mentioned – when you can turn into a chip you are pretty much unstoppable. But, the real question is whether the potato has been dealt a bad hand by the starch haters? Or if the potato is a low nutrient load of calories that diabetics should avoid and weight watchers should watch?

It’s All About the Starch

Potatoes are tubers of almost pure starch (and a whole bunch of nutrients – more on this later). It is this starch that makes them super delicious, great for frying, roasting, boiling and mashing. And it is the type and the varying amounts of the different kinds of starch that define the difference between the hundreds of varieties of potato.

The two main types of starch are amylopectin and amylose. There is a third kind as we shall see later. But for now let us concentrate on these two – as it is these two types of starch that largely effect the cooking properties and flavour of a potato.

Potatoes are either classed as waxy (high in water content and amylopectin which holds the potato together once cooked and creates a gluey or waxy texture) right through to floury (lower water content and high in amylose, which turns fluffy when cooked which makes a potato great for baking and frying, but because it has less water often needs fat to moisten it). And of course there is everything in between.

It is the variety and type of potato that confuses people about which type to use for different recipes. Traditionally it is said that the more waxy varieties of potatoes should be used salads, soups and stews; while more starchy potatoes should be used for mashing, frying and baking. But then there are top chiefs like Heston Blumenthal who swear by the use of waxy or lower starch varieties for roasting and frying. This is because they have far better flavour among other things.

Heston Blumenthal may be correct, but if you want to use a waxy potato to try and achieve a perfect crisp chip on the outside and light and fluffy on the inside then you will need to perfectly understand how the starch in the waxy potato reacts and at what temperatures. This is fine for Heston, but if you want to get results with the greatest of ease it is best to stick to the more traditional way of doing things. If you are adventurous – then please read on!

The reason why waxy potatoes work so well for Heston is because they are higher in moisture content and the fact that the method he uses to make perfect roast potatoes or chips is to triple cook the chips, leaving the potato to cool and dry out in between. A process that requires a higher water content if you don’t want a dry potato at the end. So if you plan to par boil or  par fry your potatoes go for a slightly waxier variety.

Confused? Essentially, the thing you must think about, is whether or not you want a fluffy, dry potato that will suck up fat and turn crispy when cooked; or a waxy, moist potato which will remain firm and buttery in texture. And whether or not you are going to par boil or par fry your potato first (a technique that is highly recommended for both flavour, texture and health reasons because you will get a crispier outside, fluffier inside and create a higher content of resistant starch).

(NB: Please see below for a table of the varieties of potatoes, whether they are waxy or floury and their best uses.)

Then there is the all important temperature. Starch in the potato becomes water soluble at 60°C, when the ‘semi-crystalline’ structure of the molecules swell and break. This causes the starch molecules to take up water, swell and increase in viscosity.

If the potato cools in temperature, the starch molecules begin to slightly crystallize once again which will cause the starch to squeeze out water. End result: dryness. This dryness will help form a crisp crust on the potato if you are roasting or frying it, but it will also make it taste dry which is why you want to use a slightly waxier potato for this method of cooking (as previously stated). Salting the water if you are par boiling potatoes will also significantly help you get a crisp crust on the potato if you are then going to roast or fry it. This is because it will help the outside of the potato become less moist. And the less moisture there is the more the oil can convert the sugars in the potato to a golden crisp crust.

Fat from cream or butter will somewhat moisten the potato again. And again it will increase resistant starch which is a healthy thing for your stomach and digestion as we shall soon see. But first we need to look at a few other factors.

The Controversial Potato and Its Nutrition

Let us for a minute forget about the popular delicacies that can be made out of the potato and step into the shoes of various health professionals, nutritionists and worried consumers of the potato. If you were one of these people, you may have heard some pretty bad things about this celebrated tuber over the last few decades.

One such criticism of the potato is it being nothing more than ‘a load of high GI (Glycemic Index) calories not much better than a bowl of sugar’. And it is true – the potatoes do have medium to high ratings of GI depending on the variety and the way the potato is cooked.

Generally speaking, it has been found that the more waxy varieties of potato (i.e. the higher moisture content) tend to have medium GI indexes somewhere between 56-70; while the more floury (i.e. lower water content) varieties tend to have high GI indexes between 70-95. Considering that white sugar has a GI somewhere in the mid 60’s it has led to many people making the ‘bowl of sugar comparisons’.

Since the potato has been found to be a ‘high GI’ food it has come under a lot of scrutiny by health professionals – many of which have accused the potato of being a cause of obesity and for diabetics to avoid wherever possible. Potatoes have also been examined by scientists – who have studied many varieties of potatoes for their varying GI and the way it varies when cooked and prepared in different ways. Research has found that the way a potato is cooked can vastly affect its GI (Leaving a potato to cool after it is cooked, for example, will reduce the GI significantly, which as previously stated will also make the potato more crunchy when subsequently fried or roasted!).

Perhaps the most interesting outcome from all this research however, is the way in which it has helped us come to realise how flawed the GI index method of analysis can be for making dietary decisions (GI is very useful for researchers). And nothing portrays this more than the potato and what we now know about it.

It cannot be denied that the high starch content of the potato is nothing more than easily digested carbohydrates which can quickly be broken down into sugars which enter our bloodstream and raise insulin levels. Hence the reason for the high GI rating. But, and this is a big but, in reality the actual GI of food needs to be considered as a whole. People do not tend to eat just potato. They nearly always eat potato with fat – in the form of frying oil with fries, cream with potato dauphinoise and soup, and butter and sour cream with roasted, baked and mashed potatoes. In fact, very rarely are potatoes not served with some kind of fat. And fat eaten with carbohydrates lowers the GI of a food.

In fact, this is not the only reason why the GI index is now considered to tell only a small part of the story in relation to health, diabetes, weight management and satiety. And again potatoes have played an important role in helping us realise this. We now know that other factors affect our blood sugar levels and feelings of satiety other than GI. Potatoes have a small but significant amount of Resistant Starch which is a third kind of dietary fibre (the other two types being soluble and insoluble fibre).

Resistant starch travels through the gut and small intestines undigested, which slows down the digestion process lowering the GI of your food, makes you feel more full for longer, increases fat metabolism and reduces the risk of things like diabetes, heart disease, colon cancer and obesity. If you cook potatoes and then allow them to cool you will increase the resistant starch further in a process called retrogradation.

So if you are a diabetic you do need to be aware of how potatoes will affect your blood  sugar levels. But by no means do you have to avoid them like the plague. And for everyone else we need to be aware that potatoes are a relatively high GI food – or medium GI to be more precise if you are eating them with fats – but we also need to realise that they will make us feel satiated once eaten and help keep our stomachs and digestion healthy.

Potatoes also contain all of the major vitamins and minerals with the exception of vitamins A and D, which incidentally exist in butter. Mmm. They are particularly high vitamin C, vitamin B6, potassium, tryptophan, manganese and fiber (insoluble and soluble). Although most of these nutrients and fibre are contained in the skin of the potato – eat a skinless potato and all bets are off!

All Hail the Potato

There you have it. The potato is both nutritious (as long as you are eating them with the skins, which also contain much of the flavour it must be said), filling, good for your stomach (again with the skins and even better if you cook them and then allow them to cool) and are super duper delicious!

There are a large number of varieties all with different flavours and textures. Give as many varities a go as possible and become excited about all the humble potato has to offer. Maybe consider choosing your favourite variety and see how many things you can do with it – culinarily speaking not marrying it mind you! See how it reacts differently to the different cooking methods that you employ and get to understand how the starch in a potato reacts.

Just remember that potatoes are a vegetable and are part of a healthy balanced diet. Diabetics do have to be aware of the GI of their food, but don’t let this put you off. And do be aware that many potato dishes are served with a lot of heated fat – so learn the best fats to use when cooking. See below for a table of the varieties of potatoes, whether they are waxy or floury and their best uses.

 

Table of Varieties of Potatoes By Country

It is hard to let you know which potato to use for which purpose because there is a huge number of different varieties in different countries. And as previously stated, it really does depend on what you are after. For example, sometimes I like the firmness of the waxy potatoes for roasting, while other times I want a crisp exterior with a fluffy interior – in which case I would use a floury potato. Here is a list of the different varities and their uses in some countries: