What happens when you boil potatoes? (2023)

Potatoes are one of the most versatile foods of all. you can bakeroast meat, boil or chop. Eat them warm or cold, with lots of spices or on their own. You can eat them months after harvest or fresh from the ground. The options are literally endless.

However, there's a common thread that runs through most potato dishes: they're all cooked in some way. It is very rare to see a dish made with raw potatoes, raw potato juice is just one of those few exceptions, almost every dish involves heating that potato in some way.

There's a good reason for that. Raw potatoes are not very digestible (or tasty) for humans. But once cooked, a potato will never be the same. So what happens when you cook? What makes this raw and hard potato something that is eaten all over the world?

What is a potato made of?

Before cooking, the potato is a raw part of a plant, more specifically a tuber. It is to be planted and become a new potato plant. A raw potato is "alive". It can and will germinate during storagebreathing.

The interior of a potato is fairly homogeneous, made up of cells filled with food to serve as a starting point for that plant. The skin protects the inside and is quite thin, especially for smaller, freshly harvested potatoes.

All cells within a potato share the same basic structure: the cell contains a water sac, a nucleus, and various other structures ("factories") to keep the cell running. Each cell is surrounded by a cell wall that protects the inside. These cell walls hold everything together and give a potato its strength thanks to a phenomenon calledturgor. This turgor is caused by water in the cell pushing against the cell walls. As a potato dries out and loses moisture, you'll find it softens and loses its plumpness.

Both the cells themselves and the cell walls play an important role in the texture and structure of a potato. In raw potatoes, most of the cells are intact and the cell walls are solid. However, as soon as you start cooking a potato, this changes, causing the texture of the potato to change.

Did you know that potatoes come from South America? A few centuries ago, potatoes were introduced to other regions of the world. Today it is one of the most important staple foods in the world.

Chemical composition

Perhaps not surprisingly, most of a potato is water, around 80%. This is very common with fruits and vegetables. The rest of the potato is mostly carbohydrates (>15%), most of which arepotato starch(more than 85%). Starch is a way for plants to store energy (glucose). In the case of a potato, this energy is stored to be available when it grows into a new plant. Starch settles in the cells in the form of 1 to 100 micrometer granules. Each granule is made up of a large number of starch molecules.

A potato contains hardly any fat and only a small amount of protein. Potatoes also contain many other minor components such as vitamins and minerals.

Although all starches have the same basic chemical composition, they differ in their behavior. For example, corn, potato, rice, and wheat starches are all a little different! Even starch from two different potato varieties could behave differently.

(Video) How to Boil Potatoes

cell walls

The composition of the cell walls is quite different from that of the cells themselves. They don't contain this large reservoir or water, nor do they contain the large amounts of starch. Instead, cell walls are mostly made up of large molecules like cellulose, hemicellulose, and pectins. These molecules give the potato structure and hold everything together.

What happens when you boil a potato?

When you cook a potato, your potato will change in appearance regardless of the method, whether boiled, fried, baked, or steamed. It transforms from a hard bulb into a softer, crumblier product that's easier to mash, bite, cut and chew. So what causes these transformations?

heat potato

It all starts, of course, with heating the potato. This can be done very quickly (e.g. frying thinly sliced ​​pieces) or more slowly (e.g. steaming a whole potato). Almost always heat (with amicrowaveis the exception) heat outside first. Then the heat penetrates everywhere until the whole potato is hot. The energy brought in by the heat triggers transformations and reactions in the potato.

Have you ever bought pre-cooked and parboiled potatoes and noticed that all the pieces are usually about the same size? This will help ensure that all of your potatoes cook in a similar amount of time!

"Kill" the potato.

One of the first things that happens when a potato is heated is that it "kills" it. A raw potato is alive, you can bury this potato in the ground and grow a plant. However, the heat inactivates and destroys several important components of the potato and loses its ability to become a plant again. An important component of living organisms (including humans) areEnzyme, which catalyze many vital reactions. Heat inactivates these enzymes. Once deactivated, they cannot be reactivated. You can try planting a baked potato, but it won't do much!

Chemical reaction

Deactivating these enzymes is just the beginning. Once a potato is hot enough, other chemical reactions occur that irreversibly alter the potato. You will have passed the point of no return, your potato will never be the same again!

As with any food, there are many different processes going on at the same time and we cannot talk about all of them. Instead, we'll focus on three main processes that explain many of the transformations you'll see:

1. The heat will dissolve and soften the cell walls. Individual cells no longer hold together as tightly. The cells themselves can rupture and rupture, releasing the molecules they contain. Molecules can react and cause further changes.
2. The starch absorbs water and gelatinizes.
3. At high enough temperatures, the sugars and proteins in the potato react in the Maillard reaction. This turns a potato brown and takes on many delicious flavors.

Chemical reactions don't just happen when a potato is heated. Various chemical reactions take place during storage. For example, it is known that storing a potato in the refrigerator causes the starch to break down into sugar.

disruption of the cell structure

Cell walls are the glue that holds the cells of a potato together. However, when a potato is heated, this "glue" begins to break down and with it the structure begins to break down. Cell wall pectins are known to dissolve particularly well.

Once the "glue" between the cells is softened, the eating experience of the potato will be very different as well. It will be easier to bite into a potato as the cells separate more easily. This is one of the reasons a cooked potato is softer than a raw one.

Elevated temperature also changes the permeability of a potato's cell walls. At higher temperatures, more small molecules can migrate through cell walls and cell membranes (especially above 60 °C) and change their composition.

In some cases, not only the cell walls, but also the cells themselves can weaken and even rupture. When the cells rupture, they release their components into the rest of the potato, changing the overall structure of the potato.

starch gelatinization

A significant part of a potato is starch, so the changes that potato starch undergoes during cooking have a major impact on the properties of a baked potato. We've discussed the changes that potato starch undergoes during cooking in another post, but we'll give you a quick overview here.

As the potato heats up, the starch granules in the cell absorb more and more water, causing them to swell. At some point the starch granules will burst. Each starch granule contains many individual starch molecules made up of amylose and amylopectin. These will then be "released" into the cell and some will even come out of the cell if the cell is ruptured or porous enough.

Does boiling potatoes remove potato starch?

(Video) John Says You Should Always Boil Potatoes From Cold Water | Lorraine

It's a common question, but no, boiling potatoes doesn't remove potato starch. Sure, some starch can leach out during cooking, but most of it stays in the potato. Also, if you removed all the starch from the potato, you would have very little potato left! All you would have was water with some protein and some micronutrients.

fry a potato

With some cooking methods, a potato not only softens and changes texture, but also turns brown: thinkFrench friesor fries. You only find this transformation in brewing methods that use high temperatures, well over 100°C, and where the moisture content is not too high.

The conversion itself is caused by the Maillard reaction, which is a reaction between proteins and sugars. The speed and the fact that the reaction takes place are influenced by several factors. First, the temperature, the higher the temperature, the faster it goes (that's why a skillet at 180°C will brown faster than a skillet at 140°C). Moisture content, the Maillard reaction is very slow in a very humid environment. The amount of sugar and protein in your potatoes. If your potato has more sugar, the reaction will go faster and your potatoes will brown faster.

Especially this last factor causes many differences between potatoes. If the potatoes are stored differently, are a different variety, etc., the amount and speed of browning will be different.

moisture redistribution

In addition to all these reactions that change the potato permanently, another important process takes place that is accelerated by heat: the movement of moisture.

A raw potato contains a lot of water. Depending on the cooking method, some of this water may evaporate from the potato during cooking. The extent to which moisture is removed has a major impact on the end product. Moisture leaves the potato when it is heated above the boiling point of water (100°C/212°F), such as when frying.

Removing enough moisture can make a potato crispy (we looked into thiscrispy here). In order for the whole potato to remain crispy, enough moisture must be removed from the whole piece. With a thin potato (e.g. French fries) this is of course much easier than with a large potato. For this reason, a fries is crispy all over, while a large baked potato is only crispy on the outside and stays soft and juicy on the inside.

Die Herausforderung: Keep it crunchy!

Making a crispy potato is one thing, keeping it crispy is another challenge!

The air around us is very humid, especially in humid environments. Energetically, water wants to be distributed evenly into individual phases/components (more on this underthis phenomenon here). As a result, the moisture in the air wants to re-enter the potato. If the inside of the potato still contains a lot of moisture, it migrates to the outside and softens the skin. That's why the fries are packed in a special airtight package and that's why you better eat your fries fast!

Why do floury and waxy potatoes cook so differently?

There are many different types of potatoes. They differ from wax in size, taste, shape, color and mealiness. This last descriptor is unique to potatoes and relates to how potatoes behave after cooking. A waxy potato tends to be firmer and hold its shape better, and is more difficult to mash. A floury (also starchy) potato, on the other hand, will break down more easily if you try to mash it.

Now that we know what happens when you boil a potato, we can explain this difference by looking at how the cell walls break down and how starch behaves in these varieties.

Keep in mind that most potatoes are not fully floury OR purely waxy. It's more of a continuous scale, with some very floury, some slightly waxy, etc. If you want to describe potatoes really well, you'll also need other descriptors like firmness and moisture. However, for the sake of simplicity, we'll focus on waxy and floury potatoes.

Potato Cell Breaks (Waxy) vs. Breaks (Mealy)

The processes we just discussed that go on when potatoes are cooked affect whether a potato is firm or floury. Interestingly, it is primarily the connections between the cells that are weakened in floury potatoes. The cells themselves remain in contact, but the "glue" that holds them together weakens, helping them fall apart.

In waxy potatoes, these weakened connections between cells still occur, but to a lesser extent. Also, more royal cells are damaged during the cooking process, allowing some of the starch to escape and increasing the waxy, wet mouthfeel.

Whether a potato is floury or waxy depends on its variety. This determines the composition of cell walls and cells and how they behave when heated.

starch content

As we have discussed, cooking starch plays an important role in cooking potatoes. Starch is important not only during cooking, but also afterwards when the potato cools and the starch "recrystallizes". This recrystallization can add extra strength to the potato. In general, a floury potato contains more starch than a waxy variety.

Many researchers have also looked at starch type (e.g., amylose vs. amylopectin content), granule shape and size, and how these may affect mealiness versus wax. The conclusions in this area are sometimes contradictory, so no clear links have been found.

How to cook a potato

There are literally endless ways to modify and control these scientific processes to make potatoes a little different every time. How much moisture are you removing? How long does a potato cook, i.e. how much time is left for chemical reactions? At what temperature do these processes start? While the basics remain the same, the resulting potatoes can vary wildly!

Of course, there is no perfect way to cook a potato. But there are some basic techniques that are good starting points. We'll highlight a few and focus on discussing exactly what transformations are (or aren't) taking place!

Boil potatoes in water

cook in the microwave

Mashed potatoes

dip in oil

Fry in a little oil

Bake a whole potato

Fuentes

D. Kumar, A review of factors affecting sugar content in potatoes, 2004, Ann. App Biology, 145:247-256

N. van Marle, Characterization of potato tissue changes during cooking in relation to texture development, 1997, ISBN: 90-5485-661-0,shortcut

McComber, Diane R.; Horner, Harry T.; Chamberlin, Mark A.; y Cox, David F., “Potato cultivar differences associated with mealiness” (1994). Botany publication and papers. 55http://lib.dr.iastate.edu/bot_pubs/55

Jaspreet Singh, Lovedeep Kaur, Advances in Potato Chemistry and Technology, 2016, Academic Press, Kapitel 2, 3 und 14,shortcut

VIRGINIA. Vaclavik, Fundamentals of Food Science, 2008, Third Edition, Chapter 4 Starches in Foodshortcut