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And why are those holes disappearing?
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Many people eat sliced Swiss cheese on their sandwiches and melted on burgers, but how much do you really know about this delicious dairy food? Swiss cheese isn’t just a single type of cheese at all. The original Swiss that most others are compared to is Emmental, a cheese from abroad that Americans really should try. Swiss cheeses are all of medium-hard texture and have one thing in common: They’re riddled with holes. But just why are there holes in Swiss cheese?
17 Reasons You Should Eat More Cheese
Back in the day, scientists and cheese makers believed the holes in Swiss cheese were the result of bacteria that grow during aging. S. thermophilus, Lactobacillus and P. shermani are all added to cow’s milk to make the cheese. These bacteria produce lactic acid that P. shermani bacteria then consume. While consuming the lactic acid, the P. shermani emit carbon dioxide gas. This, scientists believed, led to tiny air pockets that created the holes. In 1917, American scientist William Clark published a detailed account of this explanation, and it was widely accepted for nearly 100 years.
However, as reported by The New York Times, a study in 2015 blew a giant hole in his theory. A Swiss agricultural institute called Agroscope did some investigating after noticing the air pockets in wheels of Swiss were getting smaller. Turns out, more than bacteria is at work to burrow these holes.
During the traditional milking process involving barns and buckets, tiny particles of hay or other material often fall into the milk. At first, these particles are too small to see and so are not removed. But during aging, they weaken the otherwise sturdy structure of the curd. The bacterial gas accumulates in these spots (and only these spots) to create the holes so often seen in a slice of Swiss cheese.
So why were the holes shrinking and disappearing? Many modern dairy farms have abandoned traditional milking processes in favor of cleaner, more efficient methods. Thanks to mechanization and automation of milking, it’s no longer as likely for hay to fall into milk. As a result, modern Swiss cheese has fewer holes. So that’s one food mystery solved — here are the explanations that solved 18 more.
Why does Swiss cheese have holes?
Stephanie Clark has received funding to support research on dairy foods from the Midwest Dairy Foods Research Center, National Dairy Council, Minnesota Corn Growers Association, Agricultural Utilization Research Institute.
Partners
Iowa State University provides funding as a member of The Conversation US.
The Conversation UK receives funding from these organisations
Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected].
Why does Swiss cheese have holes? – Owen F., age 13, Belmont, Massachusetts
There are thousands of kinds of cheese, each with its own color, shape, nutritional value, flavor and texture.
Since cheese is made from milk, cheese types tend to vary based on the source of milk. Some of the most popular cheeses are made from the milk of cows, goats and sheep. But there are also cheeses made from camel milk, water buffalo milk – even moose milk.
To make cheese, you need to add bacteria to the milk. These create chemical reactions that cause it to change into a combination of solid “curds” and liquid “whey.” The whey is generally drained off, concentrated and dried into a powder.
Variations in the amount and type of bacteria influence the taste and texture of the final product. Other aspects factor into the type of cheese that’s produced: the salting method, its temperature and how long cheesemakers age it, which refers to the amount of time it is left alone to ripen and form. Some cheeses are aged for as long as 18 years.
Like many other cheeses, Swiss cheese is made with cow’s milk and contains bacteria that help convert the milk into a solid.
So why does Swiss cheese have holes? Also called “eyes,” they’re so essential to Swiss cheese that when they’re missing, the cheesemakers say the batch is “blind.”
What makes Swiss cheese “holey” is additional bacteria called Propionibacterium freudenrichii subspecies shermanii – P. shermanii for short. Under the specific conditions that Swiss cheese is made, the P. shermanii produce a gas: carbon dioxide.
Because Swiss cheese is made at a warm temperature – around 70 degrees Fahrenheit – the cheese is soft and malleable. So as the bacteria grow, the gases they emit end up creating round openings. Think of blowing a bubble with chewing gum: As you blow air from your lungs, the pressure forces the gum into a circle. The bubble eventually pops, due to air pressure from your lungs or the atmosphere.
But when a bubble has formed inside a hunk of warm cheese – and then that cheese is cooled to around 40°F – the hole stays in place. The cheese now has its eyes.
It takes about four weeks at 70°F for the eyes to form. In total, it takes about six weeks to make Swiss cheese, and then it is aged two additional months before it is sold.
Swiss cheese was first made in Switzerland in the 15th century. But there, it’s known as “emmental” or “emmentaller.”
Other countries are also known for cheeses that are similar to Swiss cheese. France has Gruyere, while Italy has Fontina. In the U.S., cheesemakers concoct a modified version, called Baby Swiss, which tends to have smaller eyes. Gouda cheese – which originated in the Netherlands – is sometimes intentionally made with cultures that produce a little bit of gas and tiny eyes.
Fontina cheese also has ‘eyes.’ Brian Yarvin/Shutterstock.com
But in most cases, cheesemakers actually try to prevent the formation of gas in their cheeses. Especially in harder cheeses, gas doesn’t lead to nice, round eyes instead, it forms unsightly crevices, cracks and splits.
Why does Swiss cheese have holes?
Stephanie Clark has received funding to support research on dairy foods from the Midwest Dairy Foods Research Center, National Dairy Council, Minnesota Corn Growers Association, Agricultural Utilization Research Institute.
Partners
Iowa State University provides funding as a member of The Conversation US.
The Conversation UK receives funding from these organisations
Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected].
Why does Swiss cheese have holes? – Owen F., age 13, Belmont, Massachusetts
There are thousands of kinds of cheese, each with its own color, shape, nutritional value, flavor and texture.
Since cheese is made from milk, cheese types tend to vary based on the source of milk. Some of the most popular cheeses are made from the milk of cows, goats and sheep. But there are also cheeses made from camel milk, water buffalo milk – even moose milk.
To make cheese, you need to add bacteria to the milk. These create chemical reactions that cause it to change into a combination of solid “curds” and liquid “whey.” The whey is generally drained off, concentrated and dried into a powder.
Variations in the amount and type of bacteria influence the taste and texture of the final product. Other aspects factor into the type of cheese that’s produced: the salting method, its temperature and how long cheesemakers age it, which refers to the amount of time it is left alone to ripen and form. Some cheeses are aged for as long as 18 years.
Like many other cheeses, Swiss cheese is made with cow’s milk and contains bacteria that help convert the milk into a solid.
So why does Swiss cheese have holes? Also called “eyes,” they’re so essential to Swiss cheese that when they’re missing, the cheesemakers say the batch is “blind.”
What makes Swiss cheese “holey” is additional bacteria called Propionibacterium freudenrichii subspecies shermanii – P. shermanii for short. Under the specific conditions that Swiss cheese is made, the P. shermanii produce a gas: carbon dioxide.
Because Swiss cheese is made at a warm temperature – around 70 degrees Fahrenheit – the cheese is soft and malleable. So as the bacteria grow, the gases they emit end up creating round openings. Think of blowing a bubble with chewing gum: As you blow air from your lungs, the pressure forces the gum into a circle. The bubble eventually pops, due to air pressure from your lungs or the atmosphere.
But when a bubble has formed inside a hunk of warm cheese – and then that cheese is cooled to around 40°F – the hole stays in place. The cheese now has its eyes.
It takes about four weeks at 70°F for the eyes to form. In total, it takes about six weeks to make Swiss cheese, and then it is aged two additional months before it is sold.
Swiss cheese was first made in Switzerland in the 15th century. But there, it’s known as “emmental” or “emmentaller.”
Other countries are also known for cheeses that are similar to Swiss cheese. France has Gruyere, while Italy has Fontina. In the U.S., cheesemakers concoct a modified version, called Baby Swiss, which tends to have smaller eyes. Gouda cheese – which originated in the Netherlands – is sometimes intentionally made with cultures that produce a little bit of gas and tiny eyes.
Fontina cheese also has ‘eyes.’ Brian Yarvin/Shutterstock.com
But in most cases, cheesemakers actually try to prevent the formation of gas in their cheeses. Especially in harder cheeses, gas doesn’t lead to nice, round eyes instead, it forms unsightly crevices, cracks and splits.
Why does Swiss cheese have holes?
Stephanie Clark has received funding to support research on dairy foods from the Midwest Dairy Foods Research Center, National Dairy Council, Minnesota Corn Growers Association, Agricultural Utilization Research Institute.
Partners
Iowa State University provides funding as a member of The Conversation US.
The Conversation UK receives funding from these organisations
Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected].
Why does Swiss cheese have holes? – Owen F., age 13, Belmont, Massachusetts
There are thousands of kinds of cheese, each with its own color, shape, nutritional value, flavor and texture.
Since cheese is made from milk, cheese types tend to vary based on the source of milk. Some of the most popular cheeses are made from the milk of cows, goats and sheep. But there are also cheeses made from camel milk, water buffalo milk – even moose milk.
To make cheese, you need to add bacteria to the milk. These create chemical reactions that cause it to change into a combination of solid “curds” and liquid “whey.” The whey is generally drained off, concentrated and dried into a powder.
Variations in the amount and type of bacteria influence the taste and texture of the final product. Other aspects factor into the type of cheese that’s produced: the salting method, its temperature and how long cheesemakers age it, which refers to the amount of time it is left alone to ripen and form. Some cheeses are aged for as long as 18 years.
Like many other cheeses, Swiss cheese is made with cow’s milk and contains bacteria that help convert the milk into a solid.
So why does Swiss cheese have holes? Also called “eyes,” they’re so essential to Swiss cheese that when they’re missing, the cheesemakers say the batch is “blind.”
What makes Swiss cheese “holey” is additional bacteria called Propionibacterium freudenrichii subspecies shermanii – P. shermanii for short. Under the specific conditions that Swiss cheese is made, the P. shermanii produce a gas: carbon dioxide.
Because Swiss cheese is made at a warm temperature – around 70 degrees Fahrenheit – the cheese is soft and malleable. So as the bacteria grow, the gases they emit end up creating round openings. Think of blowing a bubble with chewing gum: As you blow air from your lungs, the pressure forces the gum into a circle. The bubble eventually pops, due to air pressure from your lungs or the atmosphere.
But when a bubble has formed inside a hunk of warm cheese – and then that cheese is cooled to around 40°F – the hole stays in place. The cheese now has its eyes.
It takes about four weeks at 70°F for the eyes to form. In total, it takes about six weeks to make Swiss cheese, and then it is aged two additional months before it is sold.
Swiss cheese was first made in Switzerland in the 15th century. But there, it’s known as “emmental” or “emmentaller.”
Other countries are also known for cheeses that are similar to Swiss cheese. France has Gruyere, while Italy has Fontina. In the U.S., cheesemakers concoct a modified version, called Baby Swiss, which tends to have smaller eyes. Gouda cheese – which originated in the Netherlands – is sometimes intentionally made with cultures that produce a little bit of gas and tiny eyes.
Fontina cheese also has ‘eyes.’ Brian Yarvin/Shutterstock.com
But in most cases, cheesemakers actually try to prevent the formation of gas in their cheeses. Especially in harder cheeses, gas doesn’t lead to nice, round eyes instead, it forms unsightly crevices, cracks and splits.
Why does Swiss cheese have holes?
Stephanie Clark has received funding to support research on dairy foods from the Midwest Dairy Foods Research Center, National Dairy Council, Minnesota Corn Growers Association, Agricultural Utilization Research Institute.
Partners
Iowa State University provides funding as a member of The Conversation US.
The Conversation UK receives funding from these organisations
Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected].
Why does Swiss cheese have holes? – Owen F., age 13, Belmont, Massachusetts
There are thousands of kinds of cheese, each with its own color, shape, nutritional value, flavor and texture.
Since cheese is made from milk, cheese types tend to vary based on the source of milk. Some of the most popular cheeses are made from the milk of cows, goats and sheep. But there are also cheeses made from camel milk, water buffalo milk – even moose milk.
To make cheese, you need to add bacteria to the milk. These create chemical reactions that cause it to change into a combination of solid “curds” and liquid “whey.” The whey is generally drained off, concentrated and dried into a powder.
Variations in the amount and type of bacteria influence the taste and texture of the final product. Other aspects factor into the type of cheese that’s produced: the salting method, its temperature and how long cheesemakers age it, which refers to the amount of time it is left alone to ripen and form. Some cheeses are aged for as long as 18 years.
Like many other cheeses, Swiss cheese is made with cow’s milk and contains bacteria that help convert the milk into a solid.
So why does Swiss cheese have holes? Also called “eyes,” they’re so essential to Swiss cheese that when they’re missing, the cheesemakers say the batch is “blind.”
What makes Swiss cheese “holey” is additional bacteria called Propionibacterium freudenrichii subspecies shermanii – P. shermanii for short. Under the specific conditions that Swiss cheese is made, the P. shermanii produce a gas: carbon dioxide.
Because Swiss cheese is made at a warm temperature – around 70 degrees Fahrenheit – the cheese is soft and malleable. So as the bacteria grow, the gases they emit end up creating round openings. Think of blowing a bubble with chewing gum: As you blow air from your lungs, the pressure forces the gum into a circle. The bubble eventually pops, due to air pressure from your lungs or the atmosphere.
But when a bubble has formed inside a hunk of warm cheese – and then that cheese is cooled to around 40°F – the hole stays in place. The cheese now has its eyes.
It takes about four weeks at 70°F for the eyes to form. In total, it takes about six weeks to make Swiss cheese, and then it is aged two additional months before it is sold.
Swiss cheese was first made in Switzerland in the 15th century. But there, it’s known as “emmental” or “emmentaller.”
Other countries are also known for cheeses that are similar to Swiss cheese. France has Gruyere, while Italy has Fontina. In the U.S., cheesemakers concoct a modified version, called Baby Swiss, which tends to have smaller eyes. Gouda cheese – which originated in the Netherlands – is sometimes intentionally made with cultures that produce a little bit of gas and tiny eyes.
Fontina cheese also has ‘eyes.’ Brian Yarvin/Shutterstock.com
But in most cases, cheesemakers actually try to prevent the formation of gas in their cheeses. Especially in harder cheeses, gas doesn’t lead to nice, round eyes instead, it forms unsightly crevices, cracks and splits.
Why does Swiss cheese have holes?
Stephanie Clark has received funding to support research on dairy foods from the Midwest Dairy Foods Research Center, National Dairy Council, Minnesota Corn Growers Association, Agricultural Utilization Research Institute.
Partners
Iowa State University provides funding as a member of The Conversation US.
The Conversation UK receives funding from these organisations
Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected].
Why does Swiss cheese have holes? – Owen F., age 13, Belmont, Massachusetts
There are thousands of kinds of cheese, each with its own color, shape, nutritional value, flavor and texture.
Since cheese is made from milk, cheese types tend to vary based on the source of milk. Some of the most popular cheeses are made from the milk of cows, goats and sheep. But there are also cheeses made from camel milk, water buffalo milk – even moose milk.
To make cheese, you need to add bacteria to the milk. These create chemical reactions that cause it to change into a combination of solid “curds” and liquid “whey.” The whey is generally drained off, concentrated and dried into a powder.
Variations in the amount and type of bacteria influence the taste and texture of the final product. Other aspects factor into the type of cheese that’s produced: the salting method, its temperature and how long cheesemakers age it, which refers to the amount of time it is left alone to ripen and form. Some cheeses are aged for as long as 18 years.
Like many other cheeses, Swiss cheese is made with cow’s milk and contains bacteria that help convert the milk into a solid.
So why does Swiss cheese have holes? Also called “eyes,” they’re so essential to Swiss cheese that when they’re missing, the cheesemakers say the batch is “blind.”
What makes Swiss cheese “holey” is additional bacteria called Propionibacterium freudenrichii subspecies shermanii – P. shermanii for short. Under the specific conditions that Swiss cheese is made, the P. shermanii produce a gas: carbon dioxide.
Because Swiss cheese is made at a warm temperature – around 70 degrees Fahrenheit – the cheese is soft and malleable. So as the bacteria grow, the gases they emit end up creating round openings. Think of blowing a bubble with chewing gum: As you blow air from your lungs, the pressure forces the gum into a circle. The bubble eventually pops, due to air pressure from your lungs or the atmosphere.
But when a bubble has formed inside a hunk of warm cheese – and then that cheese is cooled to around 40°F – the hole stays in place. The cheese now has its eyes.
It takes about four weeks at 70°F for the eyes to form. In total, it takes about six weeks to make Swiss cheese, and then it is aged two additional months before it is sold.
Swiss cheese was first made in Switzerland in the 15th century. But there, it’s known as “emmental” or “emmentaller.”
Other countries are also known for cheeses that are similar to Swiss cheese. France has Gruyere, while Italy has Fontina. In the U.S., cheesemakers concoct a modified version, called Baby Swiss, which tends to have smaller eyes. Gouda cheese – which originated in the Netherlands – is sometimes intentionally made with cultures that produce a little bit of gas and tiny eyes.
Fontina cheese also has ‘eyes.’ Brian Yarvin/Shutterstock.com
But in most cases, cheesemakers actually try to prevent the formation of gas in their cheeses. Especially in harder cheeses, gas doesn’t lead to nice, round eyes instead, it forms unsightly crevices, cracks and splits.
Why does Swiss cheese have holes?
Stephanie Clark has received funding to support research on dairy foods from the Midwest Dairy Foods Research Center, National Dairy Council, Minnesota Corn Growers Association, Agricultural Utilization Research Institute.
Partners
Iowa State University provides funding as a member of The Conversation US.
The Conversation UK receives funding from these organisations
Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected].
Why does Swiss cheese have holes? – Owen F., age 13, Belmont, Massachusetts
There are thousands of kinds of cheese, each with its own color, shape, nutritional value, flavor and texture.
Since cheese is made from milk, cheese types tend to vary based on the source of milk. Some of the most popular cheeses are made from the milk of cows, goats and sheep. But there are also cheeses made from camel milk, water buffalo milk – even moose milk.
To make cheese, you need to add bacteria to the milk. These create chemical reactions that cause it to change into a combination of solid “curds” and liquid “whey.” The whey is generally drained off, concentrated and dried into a powder.
Variations in the amount and type of bacteria influence the taste and texture of the final product. Other aspects factor into the type of cheese that’s produced: the salting method, its temperature and how long cheesemakers age it, which refers to the amount of time it is left alone to ripen and form. Some cheeses are aged for as long as 18 years.
Like many other cheeses, Swiss cheese is made with cow’s milk and contains bacteria that help convert the milk into a solid.
So why does Swiss cheese have holes? Also called “eyes,” they’re so essential to Swiss cheese that when they’re missing, the cheesemakers say the batch is “blind.”
What makes Swiss cheese “holey” is additional bacteria called Propionibacterium freudenrichii subspecies shermanii – P. shermanii for short. Under the specific conditions that Swiss cheese is made, the P. shermanii produce a gas: carbon dioxide.
Because Swiss cheese is made at a warm temperature – around 70 degrees Fahrenheit – the cheese is soft and malleable. So as the bacteria grow, the gases they emit end up creating round openings. Think of blowing a bubble with chewing gum: As you blow air from your lungs, the pressure forces the gum into a circle. The bubble eventually pops, due to air pressure from your lungs or the atmosphere.
But when a bubble has formed inside a hunk of warm cheese – and then that cheese is cooled to around 40°F – the hole stays in place. The cheese now has its eyes.
It takes about four weeks at 70°F for the eyes to form. In total, it takes about six weeks to make Swiss cheese, and then it is aged two additional months before it is sold.
Swiss cheese was first made in Switzerland in the 15th century. But there, it’s known as “emmental” or “emmentaller.”
Other countries are also known for cheeses that are similar to Swiss cheese. France has Gruyere, while Italy has Fontina. In the U.S., cheesemakers concoct a modified version, called Baby Swiss, which tends to have smaller eyes. Gouda cheese – which originated in the Netherlands – is sometimes intentionally made with cultures that produce a little bit of gas and tiny eyes.
Fontina cheese also has ‘eyes.’ Brian Yarvin/Shutterstock.com
But in most cases, cheesemakers actually try to prevent the formation of gas in their cheeses. Especially in harder cheeses, gas doesn’t lead to nice, round eyes instead, it forms unsightly crevices, cracks and splits.
Why does Swiss cheese have holes?
Stephanie Clark has received funding to support research on dairy foods from the Midwest Dairy Foods Research Center, National Dairy Council, Minnesota Corn Growers Association, Agricultural Utilization Research Institute.
Partners
Iowa State University provides funding as a member of The Conversation US.
The Conversation UK receives funding from these organisations
Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected].
Why does Swiss cheese have holes? – Owen F., age 13, Belmont, Massachusetts
There are thousands of kinds of cheese, each with its own color, shape, nutritional value, flavor and texture.
Since cheese is made from milk, cheese types tend to vary based on the source of milk. Some of the most popular cheeses are made from the milk of cows, goats and sheep. But there are also cheeses made from camel milk, water buffalo milk – even moose milk.
To make cheese, you need to add bacteria to the milk. These create chemical reactions that cause it to change into a combination of solid “curds” and liquid “whey.” The whey is generally drained off, concentrated and dried into a powder.
Variations in the amount and type of bacteria influence the taste and texture of the final product. Other aspects factor into the type of cheese that’s produced: the salting method, its temperature and how long cheesemakers age it, which refers to the amount of time it is left alone to ripen and form. Some cheeses are aged for as long as 18 years.
Like many other cheeses, Swiss cheese is made with cow’s milk and contains bacteria that help convert the milk into a solid.
So why does Swiss cheese have holes? Also called “eyes,” they’re so essential to Swiss cheese that when they’re missing, the cheesemakers say the batch is “blind.”
What makes Swiss cheese “holey” is additional bacteria called Propionibacterium freudenrichii subspecies shermanii – P. shermanii for short. Under the specific conditions that Swiss cheese is made, the P. shermanii produce a gas: carbon dioxide.
Because Swiss cheese is made at a warm temperature – around 70 degrees Fahrenheit – the cheese is soft and malleable. So as the bacteria grow, the gases they emit end up creating round openings. Think of blowing a bubble with chewing gum: As you blow air from your lungs, the pressure forces the gum into a circle. The bubble eventually pops, due to air pressure from your lungs or the atmosphere.
But when a bubble has formed inside a hunk of warm cheese – and then that cheese is cooled to around 40°F – the hole stays in place. The cheese now has its eyes.
It takes about four weeks at 70°F for the eyes to form. In total, it takes about six weeks to make Swiss cheese, and then it is aged two additional months before it is sold.
Swiss cheese was first made in Switzerland in the 15th century. But there, it’s known as “emmental” or “emmentaller.”
Other countries are also known for cheeses that are similar to Swiss cheese. France has Gruyere, while Italy has Fontina. In the U.S., cheesemakers concoct a modified version, called Baby Swiss, which tends to have smaller eyes. Gouda cheese – which originated in the Netherlands – is sometimes intentionally made with cultures that produce a little bit of gas and tiny eyes.
Fontina cheese also has ‘eyes.’ Brian Yarvin/Shutterstock.com
But in most cases, cheesemakers actually try to prevent the formation of gas in their cheeses. Especially in harder cheeses, gas doesn’t lead to nice, round eyes instead, it forms unsightly crevices, cracks and splits.
Why does Swiss cheese have holes?
Stephanie Clark has received funding to support research on dairy foods from the Midwest Dairy Foods Research Center, National Dairy Council, Minnesota Corn Growers Association, Agricultural Utilization Research Institute.
Partners
Iowa State University provides funding as a member of The Conversation US.
The Conversation UK receives funding from these organisations
Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected].
Why does Swiss cheese have holes? – Owen F., age 13, Belmont, Massachusetts
There are thousands of kinds of cheese, each with its own color, shape, nutritional value, flavor and texture.
Since cheese is made from milk, cheese types tend to vary based on the source of milk. Some of the most popular cheeses are made from the milk of cows, goats and sheep. But there are also cheeses made from camel milk, water buffalo milk – even moose milk.
To make cheese, you need to add bacteria to the milk. These create chemical reactions that cause it to change into a combination of solid “curds” and liquid “whey.” The whey is generally drained off, concentrated and dried into a powder.
Variations in the amount and type of bacteria influence the taste and texture of the final product. Other aspects factor into the type of cheese that’s produced: the salting method, its temperature and how long cheesemakers age it, which refers to the amount of time it is left alone to ripen and form. Some cheeses are aged for as long as 18 years.
Like many other cheeses, Swiss cheese is made with cow’s milk and contains bacteria that help convert the milk into a solid.
So why does Swiss cheese have holes? Also called “eyes,” they’re so essential to Swiss cheese that when they’re missing, the cheesemakers say the batch is “blind.”
What makes Swiss cheese “holey” is additional bacteria called Propionibacterium freudenrichii subspecies shermanii – P. shermanii for short. Under the specific conditions that Swiss cheese is made, the P. shermanii produce a gas: carbon dioxide.
Because Swiss cheese is made at a warm temperature – around 70 degrees Fahrenheit – the cheese is soft and malleable. So as the bacteria grow, the gases they emit end up creating round openings. Think of blowing a bubble with chewing gum: As you blow air from your lungs, the pressure forces the gum into a circle. The bubble eventually pops, due to air pressure from your lungs or the atmosphere.
But when a bubble has formed inside a hunk of warm cheese – and then that cheese is cooled to around 40°F – the hole stays in place. The cheese now has its eyes.
It takes about four weeks at 70°F for the eyes to form. In total, it takes about six weeks to make Swiss cheese, and then it is aged two additional months before it is sold.
Swiss cheese was first made in Switzerland in the 15th century. But there, it’s known as “emmental” or “emmentaller.”
Other countries are also known for cheeses that are similar to Swiss cheese. France has Gruyere, while Italy has Fontina. In the U.S., cheesemakers concoct a modified version, called Baby Swiss, which tends to have smaller eyes. Gouda cheese – which originated in the Netherlands – is sometimes intentionally made with cultures that produce a little bit of gas and tiny eyes.
Fontina cheese also has ‘eyes.’ Brian Yarvin/Shutterstock.com
But in most cases, cheesemakers actually try to prevent the formation of gas in their cheeses. Especially in harder cheeses, gas doesn’t lead to nice, round eyes instead, it forms unsightly crevices, cracks and splits.
Why does Swiss cheese have holes?
Stephanie Clark has received funding to support research on dairy foods from the Midwest Dairy Foods Research Center, National Dairy Council, Minnesota Corn Growers Association, Agricultural Utilization Research Institute.
Partners
Iowa State University provides funding as a member of The Conversation US.
The Conversation UK receives funding from these organisations
Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected].
Why does Swiss cheese have holes? – Owen F., age 13, Belmont, Massachusetts
There are thousands of kinds of cheese, each with its own color, shape, nutritional value, flavor and texture.
Since cheese is made from milk, cheese types tend to vary based on the source of milk. Some of the most popular cheeses are made from the milk of cows, goats and sheep. But there are also cheeses made from camel milk, water buffalo milk – even moose milk.
To make cheese, you need to add bacteria to the milk. These create chemical reactions that cause it to change into a combination of solid “curds” and liquid “whey.” The whey is generally drained off, concentrated and dried into a powder.
Variations in the amount and type of bacteria influence the taste and texture of the final product. Other aspects factor into the type of cheese that’s produced: the salting method, its temperature and how long cheesemakers age it, which refers to the amount of time it is left alone to ripen and form. Some cheeses are aged for as long as 18 years.
Like many other cheeses, Swiss cheese is made with cow’s milk and contains bacteria that help convert the milk into a solid.
So why does Swiss cheese have holes? Also called “eyes,” they’re so essential to Swiss cheese that when they’re missing, the cheesemakers say the batch is “blind.”
What makes Swiss cheese “holey” is additional bacteria called Propionibacterium freudenrichii subspecies shermanii – P. shermanii for short. Under the specific conditions that Swiss cheese is made, the P. shermanii produce a gas: carbon dioxide.
Because Swiss cheese is made at a warm temperature – around 70 degrees Fahrenheit – the cheese is soft and malleable. So as the bacteria grow, the gases they emit end up creating round openings. Think of blowing a bubble with chewing gum: As you blow air from your lungs, the pressure forces the gum into a circle. The bubble eventually pops, due to air pressure from your lungs or the atmosphere.
But when a bubble has formed inside a hunk of warm cheese – and then that cheese is cooled to around 40°F – the hole stays in place. The cheese now has its eyes.
It takes about four weeks at 70°F for the eyes to form. In total, it takes about six weeks to make Swiss cheese, and then it is aged two additional months before it is sold.
Swiss cheese was first made in Switzerland in the 15th century. But there, it’s known as “emmental” or “emmentaller.”
Other countries are also known for cheeses that are similar to Swiss cheese. France has Gruyere, while Italy has Fontina. In the U.S., cheesemakers concoct a modified version, called Baby Swiss, which tends to have smaller eyes. Gouda cheese – which originated in the Netherlands – is sometimes intentionally made with cultures that produce a little bit of gas and tiny eyes.
Fontina cheese also has ‘eyes.’ Brian Yarvin/Shutterstock.com
But in most cases, cheesemakers actually try to prevent the formation of gas in their cheeses. Especially in harder cheeses, gas doesn’t lead to nice, round eyes instead, it forms unsightly crevices, cracks and splits.
Why does Swiss cheese have holes?
Stephanie Clark has received funding to support research on dairy foods from the Midwest Dairy Foods Research Center, National Dairy Council, Minnesota Corn Growers Association, Agricultural Utilization Research Institute.
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Why does Swiss cheese have holes? – Owen F., age 13, Belmont, Massachusetts
There are thousands of kinds of cheese, each with its own color, shape, nutritional value, flavor and texture.
Since cheese is made from milk, cheese types tend to vary based on the source of milk. Some of the most popular cheeses are made from the milk of cows, goats and sheep. But there are also cheeses made from camel milk, water buffalo milk – even moose milk.
To make cheese, you need to add bacteria to the milk. These create chemical reactions that cause it to change into a combination of solid “curds” and liquid “whey.” The whey is generally drained off, concentrated and dried into a powder.
Variations in the amount and type of bacteria influence the taste and texture of the final product. Other aspects factor into the type of cheese that’s produced: the salting method, its temperature and how long cheesemakers age it, which refers to the amount of time it is left alone to ripen and form. Some cheeses are aged for as long as 18 years.
Like many other cheeses, Swiss cheese is made with cow’s milk and contains bacteria that help convert the milk into a solid.
So why does Swiss cheese have holes? Also called “eyes,” they’re so essential to Swiss cheese that when they’re missing, the cheesemakers say the batch is “blind.”
What makes Swiss cheese “holey” is additional bacteria called Propionibacterium freudenrichii subspecies shermanii – P. shermanii for short. Under the specific conditions that Swiss cheese is made, the P. shermanii produce a gas: carbon dioxide.
Because Swiss cheese is made at a warm temperature – around 70 degrees Fahrenheit – the cheese is soft and malleable. So as the bacteria grow, the gases they emit end up creating round openings. Think of blowing a bubble with chewing gum: As you blow air from your lungs, the pressure forces the gum into a circle. The bubble eventually pops, due to air pressure from your lungs or the atmosphere.
But when a bubble has formed inside a hunk of warm cheese – and then that cheese is cooled to around 40°F – the hole stays in place. The cheese now has its eyes.
It takes about four weeks at 70°F for the eyes to form. In total, it takes about six weeks to make Swiss cheese, and then it is aged two additional months before it is sold.
Swiss cheese was first made in Switzerland in the 15th century. But there, it’s known as “emmental” or “emmentaller.”
Other countries are also known for cheeses that are similar to Swiss cheese. France has Gruyere, while Italy has Fontina. In the U.S., cheesemakers concoct a modified version, called Baby Swiss, which tends to have smaller eyes. Gouda cheese – which originated in the Netherlands – is sometimes intentionally made with cultures that produce a little bit of gas and tiny eyes.
Fontina cheese also has ‘eyes.’ Brian Yarvin/Shutterstock.com
But in most cases, cheesemakers actually try to prevent the formation of gas in their cheeses. Especially in harder cheeses, gas doesn’t lead to nice, round eyes instead, it forms unsightly crevices, cracks and splits.