How do fish farms work? Fish farms work by raising fish from eggs to full sized fish in a carefully controlled environment.

There are different ways to farm fish, and they all have their benefits and problems, but they are all trying to overcome a situation that we have created ourselves. The situation is that we have overfished the seas and there are not enough fish left. If we continue to fish industrially in the way that we have been, many fish stocks could collapse. Farming fish can help with this problem because fish can be bred specifically for the market, leaving fish in the oceans some breathing room so their stocks can be replenished. It is not necessarily kind to the fish being farmed, and some intensive fish farms have been compared to factory farming, but it is one possible solution.

Two common ways of farming fish are in a fish pen or in a cage in the open sea or a lake. In both cases, fish eggs are taken out of female fish and raised in hatchery tanks until they have reached a certain size before they are released into the pens or the cages. Once there, the fish are given food designed to make them grow as quickly as possible, and then they are harvested. Fish pens are enclosed ponds that are cut off from a natural water source. Fish need oxygen, obviously, so fish pens need a large supply of water to replace the oxygen in the pen. Fish cages are large and very deep cages that float in the sea. They are open at the top and descend to different depths depending on the type of fish being raised. The fish have a lot more space to swim around in and the water from the ocean flows through the cage, which means the farm doesn’t need to pump in fresh water. Although, often, so many fish are farmed in the same cage that they don’t really have space to swim.

Fish farms have been around for at least three thousand years and possibly more. People realized that it was easier to raise some fish in captivity than it was to go out and catch them. Archaeological evidence has shown that both the Egyptians and the Romans employed fish farms. However, they were not the most common way of catching fish because they have a lot of problems and they were expensive. It was still far easier for people to make a living as fishermen. That changed once industrial fishing became a thing in the late 19^th century when steam powered fishing trawlers were invented. Ships could travel further and catch far more fish than sailing ships ever could. That worsened when modern diesel trawlers were invented and then factory ships were invented in the 1950s and we rapidly overfished the oceans. A factory ship can stay out for long periods of time and process and freeze all the fish it catches.

Fish, shellfish, and crustacean farming has gradually increased year by year. In 2022, for the first time, farmed aquatic animals made up 51% of global aquatic animal production.

Fish farms have obvious advantages. Fish can be raised almost anywhere on the planet, and they are very easy to catch. Fish can be raised in areas where they wouldn’t naturally be found, which means they don’t have to be shipped internationally, which is better for the environment. We can raise as many fish as we need without having to overfish the oceans.  

There are also a lot of problems, though, that are proving very difficult to solve. The first is disease. When fish are raised naturally in the ocean, they are spread out so diseases don’t easily jump from fish to fish. In a fish pen or a cage, they are confined and diseases can become a real problem. Pests like sea lice also multiply very easily in the confined conditions. In a sea cage, these can spread to local fish as well. Pollution is a problem as well. In some fish farms, antibiotics may be used to treat or prevent disease, and in some places, they have also been used to promote growth. Pesticides are also heavily used to keep the bugs and pests away.  In a pen, the water is constantly changed, but not always fast enough and pollution from the fish can build up. The water from the pen is often just pumped into a river without being treated and that can spread the pollution. In fish cages, the water changes, but the pollution from the fish gets washed into the ocean and can have an effect on the local ecosystems. Escapes are also a problem. Millions of fish escape from fish cages every year. These fish are not always native to the local area and they can become an invasive species, outcompeting native fish. Farmed fish are also expensive because they have to be fed special food and the infrastructure is very expensive to maintain. There are many other problems with fish farms as well, but we cannot continue to overfish the oceans. I wonder what the solution is. And this is what I learned today.

Sources

https://en.wikipedia.org/wiki/Fish_farming

https://www.nationalgeographic.com/foodfeatures/aquaculture

https://en.wikipedia.org/wiki/History_of_fishing

Photo by Ali Düzdemir: https://www.pexels.com/photo/motorboats-and-boat-near-fishing-nets-on-lake-18640095/

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Why does starch thicken sauce? Starch thickens sauces because starch granules swell when they are heated in water. As they swell, they trap water and release long starch molecules that tangle together, turning a thin liquid into a thicker one.

Starch is a complex carbohydrate that is produced by green plants as their main way of storing energy. Plants usually store it in their roots, tubers, seeds, and grains. Starch is a natural polymer, which means it is made from many smaller molecules joined together in a long chain. Plastic is a human-made polymer, and starch is a natural one. A polymer is not stronger than an atom in a simple sense, but it has different properties because all of its smaller parts are linked together.

Starch is made from glucose molecules. There are two main kinds of starch molecule: amylose and amylopectin. Amylose is mostly a long, straight chain of glucose molecules. Amylopectin is also made from glucose, but it is branched, like a tree with many smaller branches coming off the main trunk. Different plants have different amounts of each, but many common starches are roughly 20% amylose and 80% amylopectin.

Plants produce glucose when they photosynthesize, but they don’t use all of that glucose straight away. They store what they don’t use as starch, and they can use it later when they don’t have enough sunlight, or when they are producing new leaves in the spring. Plants move sugar around in their sap, often as sucrose rather than glucose. This is the sugar-rich liquid that people tap from maple trees to make maple syrup. When plants make starch, they add glucose units one at a time to a growing chain.

We eat an enormous amount of natural starch. Rice, potatoes, wheat, corn, beans, pasta, bread, and many root vegetables are full of it. Some fruits and vegetables contain starch as well, although fruit usually contains more simple sugars than starch, especially when it is ripe. Some starch is broken down quickly by our bodies, but some passes farther through the digestive system. This is called resistant starch, and the microbes in our gut can feed on it.

Humans use an enormous amount of starch every year. It is taken out of plants by grinding them, then washing, sieving, and drying them. Corn is one of the most common sources because corn kernels contain a large amount of starch and corn can be grown cheaply in huge quantities. Wheat, potatoes, and tapioca are also important sources. A lot of corn is also turned into sweeteners, such as corn syrup, which is one reason corn appears in so many processed foods.

Cornstarch is made by soaking corn kernels so they become softer. The different parts of the kernel are then separated and ground. The ground material is washed so the starch can be pulled away from the fiber, protein, and oil. After that, machines separate and dry the starch until it becomes the fine white powder used in kitchens and factories. Starch is not only used in food. People have used it for glues, paper, cloth, and many other things for a very long time.

One of the most familiar uses of starch is thickening sauces. To thicken a sauce, the starch is usually mixed with a small amount of cold liquid first to make a slurry. The liquid does not make the starch dissolve. It just spreads the starch granules out evenly so they don’t clump together. If dry starch is poured straight into hot sauce, the outside of each little lump thickens almost instantly, trapping dry starch inside. That is why lumps form and why they are so difficult to remove.

When the starch slurry is added to the hot liquid, nothing much happens at first. The sauce may still look thin. The change begins when the starch granules get hot enough. The exact temperature depends on the kind of starch, but many starches start to thicken somewhere above 60℃, and they thicken more as they get closer to boiling. The granules absorb water and swell. As they swell, some amylose leaks out into the liquid. These long molecules begin to bump into each other and tangle together.

That tangle is what thickens the sauce. The swollen granules and loose starch molecules form a kind of soft mesh through the liquid. The water is still there, but it can no longer move around as freely as before. The sauce becomes thicker, smoother, and glossier. This process is called gelatinization.

However, starch-thickened sauces are not indestructible. If they are boiled too long, stirred too hard, or exposed to too much acid, the starch network can start to break down. When that happens, the sauce can become thin again. That is why starch-thickened sauces usually work best when they are heated until thick, then cooked gently.

Why does starch thicken sauce? It is because tiny starch granules change shape when they are heated in water. They swell, leak long molecules, and build a loose net that holds the water in place. A thin liquid becomes a sauce because the water is trapped inside a starch web. And this is what I learned today.

Sources

https://www.thespruceeats.com/thicken-a-sauce-with-cornstarch-996071

https://en.wikipedia.org/wiki/Corn_starch

https://en.wikipedia.org/wiki/Starch

https://www.bbc.co.uk/bitesize/articles/zxwwsrd#zbxwwnb

https://www.vedantu.com/biology/difference-between-amylose-and-amylopectin

Photo by cottonbro studio: https://www.pexels.com/photo/close-up-of-cooking-7696492/

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What is jerky? Jerky is traditionally strips of dried meat that are eaten as a snack or as a way to get protein and energy on long journeys where there is no access to refrigeration.

The concept of jerky has been around for thousands of years, but the word has only existed in English since the 19th century. It came into English from Spanish, which picked it up from a word used by Indigenous people of the Andes. Their word was “ch’arki,” which meant dried flesh. That changed to “charqui” in Spanish, which changed again to “jerky” in English. The Spanish took the word from the Incas, but the concept of jerky has existed in almost every culture since the early days of civilization because drying meat is an excellent way to preserve it.

As soon as any animal dies, the meat starts to spoil. Most people have probably found that carrots or potatoes can be left on a kitchen counter for a couple of weeks and still be fairly edible, albeit a little bit soft. If a piece of chicken or pork is left on a kitchen counter for a couple of weeks, even getting past the smell would be difficult, and eating it would be dangerous. Meat has a lot of protein, which bacteria can feed on. It also has a lot of moisture and a fairly neutral pH. All of these things make ideal conditions for bacteria and make meat spoil faster than many vegetables.

Some of the bacteria that can grow on meat, such as Salmonella and E. coli, can make people very sick. Other bacteria can produce toxins as they grow. Some of these toxins are not easy for the human body to deal with, and some are not destroyed just because the food is cooked. This is why rotten meat is so dangerous. Animals such as vultures and hyenas have much stronger stomach acid and different digestive systems, which allows them to eat food that would make a human very ill.

These days, meat can be frozen, which preserves it for a very long time, or it can be put in a refrigerator, which extends its life for a few days. Bacteria cannot function well in low temperatures. Freezing doesn’t necessarily kill the bacteria. It mostly just stops them from working. Once the meat warms up again, the bacteria can start multiplying again.

Before refrigeration, the main ways to stop meat from spoiling were to salt it, pickle it, smoke it, or dry it. Salt works because it pulls water out of the meat and out of the bacteria. Vinegar works because its acidity makes life very difficult for bacteria. Drying works because bacteria and mold need water to carry out their chemical reactions. With not enough available water, they cannot grow properly, and the food lasts much longer. Smoking meat can also help because smoke contains chemicals that slow down bacteria and mold, and it dries the surface of the meat. It also adds a lot of flavor.

Jerky can be made from almost any kind of meat or fish. It usually refers to meat, but the basic idea can be used with many foods. When it is prepared, the fat is trimmed off first. This is because fat does not dry in the same way as meat. Muscle contains a lot of water, so that water can be removed. Fat contains very little water, so there is not much to remove. Instead, fat can go rancid. This means it reacts with oxygen and develops a bad smell and taste. If too much fat is left on jerky, the meat will not last as long.

The meat also has to be cut very thin so that it dries quickly and evenly. If the outside dries but the inside stays wet, bacteria can still grow inside the meat. Modern drying methods use low-temperature drying ovens or dehydrators with heating elements and fans. The warm air moves over the meat and evaporates the moisture. This can dry the meat in a few hours. Commercial jerky also usually contains a lot of salt, and some types use preservatives as well. It is then sealed in packaging so that moisture and air cannot easily get back in.

Modern jerky can last a long time and still be edible. Traditionally, though, the process was much simpler. The fat was removed, the meat was cut into thin strips, and then it was dried in the sun, wind, or smoke. A hot, dry day with a strong wind would be best because that is basically what modern dehydrators are trying to copy. The goal is to remove the water before bacteria have time to spoil the meat.

Like many other methods of food preservation, people probably discovered this by accident. They would have noticed that meat left in a hot, dry place lasted longer than meat that stayed wet. From there, they improved the method over generations. They learned to cut the meat thinner, remove the fat, add salt, use smoke, and choose the right weather. Jerky looks like a simple snack today, but it is really an ancient survival technology. It allowed people to carry protein across deserts, mountains, oceans, and long journeys before anyone had a refrigerator. And this is what I learned today.

Sources

https://en.wikipedia.org/wiki/Jerky

https://www.etymonline.com/word/jerky

https://en.wikipedia.org/wiki/Curing_(food_preservation)

https://agriculture.institute/meat-science-fundamentals/drying-meat-preservation-ancient-technique

Photo by Almendra López Varela: https://www.pexels.com/photo/slices-of-meat-o-a-wooden-chopping-board-with-lime-and-salt-8144520/

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Why were spices so valuable in the past? You can buy a jar of spices today for a few dollars, but for a large part of history, some spices were extremely valuable. A few were even said to be worth their weight in gold. This was generally down to how hard they were to get, how many people were involved in moving them, and the image they carried.

These days, people think nothing of adding black pepper to a meal or putting cinnamon on ice cream. The majority of spices today are fairly cheap. The one spice that is still famously expensive is saffron, and that is because it is so labor-intensive to produce. Saffron comes from the red stigmas of the saffron crocus. Each flower only produces three of these tiny threads, and they have to be picked by hand. It can take tens of thousands of flowers to make even a small amount of dried saffron. That is why high-quality saffron can still cost thousands of dollars per kilogram. Still, the majority of spices are much cheaper now, but they weren’t always that way.

The main reason spices used to be expensive was rarity. Spices need certain climates and particular soils to grow, which meant that many of the most desired spices came from South Asia and Southeast Asia. Pepper came from India. Cinnamon came from Sri Lanka and other parts of Asia. Nutmeg and cloves came from islands in what is now Indonesia. If people in Europe wanted to use these spices, they had to get them from very far away.

That did not mean there was no sea trade at all. There were ancient sea routes across the Indian Ocean and through the Red Sea. However, for a long time, Europeans did not have a direct sea route to the spice-growing regions. Spices had to pass through many hands before they reached European markets. Merchants bought them, moved them, sold them on, taxed them, and protected them. Every step added cost. A bag of pepper might travel thousands of kilometers before it reached a wealthy household in Europe. By the time it arrived, it was no longer just a plant product. It was a luxury item with a long story behind it.

The Silk Road and the maritime trade routes grew partly because of this trade in silk, spices, perfumes, precious stones, and other luxury goods. However, the journey was difficult and dangerous. Ships could sink. Caravans could be attacked. Empires could block routes or demand taxes. A war, a storm, or a change in political control could suddenly make spices harder to get. This severely cut the supply. Demand was high, and when demand is high and supply is low, prices usually rise.

Spices had several uses in Europe. Obviously, they were used in food, but they were so expensive that only the wealthy could afford many of them regularly. The majority of people would have rarely seen them. Spices also became a way to show status. A rich person could use spices at a feast to show guests that they had money and connections. The spice itself tasted good, but the message was almost as important as the flavor.

Spices were also used in medicine, religious ceremonies, perfumes, and embalming. In the past, people often believed that strong smells and rare ingredients had special powers. Some spices were thought to warm the body, balance the body, or protect people from sickness. They were also used in religious rituals because fragrant and expensive materials seemed suitable for offerings and ceremonies. Ancient Egyptians used spices and aromatic substances in mummification as well. Again, these uses were mostly for people and institutions that could afford them.

Spices were so valuable that they also became commodities. They could be traded, stored, taxed, and exchanged. They were light, portable, and valuable, which made them very useful for long-distance trade. A small sack of spice could be worth a large amount of money. That is one reason European powers became so interested in controlling the spice trade. Portugal, the Netherlands, Britain, Spain, and France all competed for routes, ports, and islands connected to spices. The fight for spices helped shape the Age of Exploration and the early history of global trade.

So, why did spices become cheaper? Two main things happened. The first was that European sailors opened a direct sea route around the southern tip of Africa to the Indian Ocean. Once ships could sail from Europe to India and beyond, they could carry far more cargo than an overland caravan. The voyage was still long and dangerous, but it changed the balance of trade. Spices did not have to pass through as many middlemen, and supply increased.

The second thing that happened was that people began to grow spices in more places. This did not work for every spice, but over time, plants and seeds were moved to new colonies and new climates. Pepper, cinnamon, cloves, nutmeg, and other spices slowly became less rare. As supply increased, prices fell. The process was not instant. Spices were still relatively expensive for a long time. However, by the modern age, global trade, farming, shipping, and supermarkets had turned many former luxuries into ordinary kitchen ingredients.

That is why spices are so interesting. A jar of cinnamon or pepper looks small and ordinary now, but it carries a huge history. Spices helped connect continents. They made merchants rich. They encouraged exploration, empire, war, medicine, cooking, and global trade. What now sits quietly in a kitchen cupboard was once important enough to change the world. And that is what I learned today.

Sources

https://en.wikipedia.org/wiki/Spice_trade

https://www.bbc.com/future/bespoke/made-on-earth/the-flavours-that-shaped-the-world

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Who was Mrs. Beeton? Mrs. Beeton was Isabella Beeton. If you are British, you have probably heard her name in reference to all of the household management and recipe books that were released in her name. Even if you are not British, there is a strong chance that you have heard of her.

I say that these books were released in Mrs. Beeton’s name because she actually died when she was only 28 years old, and her husband went on to produce many books with her name on the cover. He was a very effective businessman, and once he realized how popular the books were, he went on to make her name into a brand name.

Isabella Beeton was famous for being able to manage a household with many people in it and for making meals for large numbers of people. She actually learned how to do all of this through necessity. She was born Isabella Mayson in 1836, into a lower middle class family and was one of four children. Her father died when she was only four years old, and her mother remarried a man who had four children of his own. After her second marriage, Isabella’s mother and step-father went on to have a further 13 children, bringing the grand total up to 21. They were not tremendously well-off and, as the eldest child, Isabella had a lot of practice managing the household and preparing meals for all of the children.

She met her husband, Samuel Beeton in 1854, and he was five years older than her. He was an established publisher of books and magazines, and Isabella began to write for his publications, mainly “The Englishwoman’s Domestic Magazine”. She wrote about keeping a household and she also wrote compendiums of recipes. She didn’t create the recipes herself, but copied from many other sources. Copyright was not protected so strictly back then.

The Beeton’s decided to take a couple of years’ worth of installments from the magazine and turn them into a book. The book, today known as “Mrs. Beeton’s Book of Household Management” had a much less catchy name when it was released in 1861. It was called “The Book of Household Management, comprising information for the Mistress, Housekeeper, Cook, Kitchen-Maid, Butler, Footman, Coachman, Valet, Upper and Under House-Maids, Lady’s-Maid, Maid-of-all-Work, Laundry-Maid, Nurse and Nurse-Maid, Monthly Wet and Sick Nurses, etc. etc. – also Sanitary, Medical, & Legal Memoranda: with a History of the Origin, Properties, and Uses of all Things Connected with Home Life and Comfort.” The book had 1,112 pages, 900 recipes, and only one of those recipes, one for soup, was actually created by Isabella Beeton. She might not have come up with the recipes herself, but she did revolutionize the way they were structured. We are so used to seeing the list of ingredients at the top of a recipe that we could easily think that was the only way to present it, but putting the ingredients first was Mrs. Beeton’s idea. Before her, ingredients were just mentioned in passing, or sometimes not even included at all.

Not all of the recipes were good though and Mrs. Beeton was very against “foreign” food. That included pasta, tomatoes, mangoes, lobster, garlic, and even potatoes. She recommended that pasta needed to be boiled for an hour and forty-five minutes.

The book became instantly popular and 60,000 copies were sold in its very first year of print. The content has increased since then, and the title has changed, but the book has never been out of print in over 160 years.

Unfortunately, a few years after the publication of the book that would make her famous and her husband rich, Isabella Beeton died. She was only 28 years old. She died the day after giving birth to her son from a bacterial infection. After she died, the book grew in popularity. Early editions contained an obituary to her at the front, but that was quickly removed. Her husband was a canny salesman, and he realized there was more benefit in having people think Mrs. Beaton was still alive.

After a few years, he included her name on the cover of the book, which only served to increase sales. He went on to produce any other books under her name, but Mrs. Beeton’s Book of Household Management has always been the most popular. It is still in print, but it has changed somewhat. The current edition has over 2,000 pages. And this is what I learned today.

Sources

https://en.wikipedia.org/wiki/Mrs._Beeton%27s_Book_of_Household_Management

https://www.bbc.co.uk/history/historic_figures/beeton_mrs.shtml

https://en.wikipedia.org/wiki/Isabella_Beeton

Image By https://wellcomeimages.org/indexplus/obf_images/41/48/a8689d18d643fbf0d65aafb2c367.jpgGallery: https://wellcomeimages.org/indexplus/image/L0042710.html, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=36107779

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Why does oil splash when cooking? Oil splashes when cooking because water in the food hits the hot oil and instantly vaporizes into steam. If you have ever dropped food into a frying pan and been sprayed with hot oil, you’lI understand this problem. It basically comes down to the heat of the oil, the temperature water vaporizes at, and the way water expands when it turns into steam.

Every liquid has a temperature at which it boils, called the boiling point. This is the point where the molecules in the liquid have absorbed too much energy from the heat source to remain stable as a liquid, and they break away, forming a vapor. The boiling point for every liquid is different because different molecules can absorb different amounts of thermal energy before changing state. For water, at sea level, that temperature is 100°C. If enough thermal energy is supplied to water molecules to get them above 100°C, they will no longer remain liquid and they will become vapor, which we call steam. Oils can get much hotter than this while still remaining liquid, which is why frying works so well.

When frying, the oil is usually put into the pan first and brought up to heat. The oil absorbs a lot of energy and quickly rises above the 100°C needed to boil water. When the food is added, any water inside it very quickly absorbs thermal energy from the oil and reaches its boiling point. The water molecules begin moving more and taking up far more space than they did as liquid. They cannot simply stay where they are, so they form steam bubbles inside the oil.

As more of the water turns to steam, the bubble grows larger and begins to rise toward the top of the oil because it is less dense than the liquid around it. When it reaches the surface, it bursts out into the air and throws some of the oil up with it. That is the splash. If something has a lot of moisture in it, there will be more steam bubbles, which means more splashing. If something is extremely wet, especially in deep-frying, so much steam can be produced so quickly that the oil foams and swells upward. In a bad case, it can boil over the edge of the pot. This can be very dangerous.

The best way to avoid this is to dry the food as much as possible before cooking, although it is impossible to remove all of the water from food. Patting it dry with paper towels can help a lot. This is especially important with foods like fish, potatoes, or anything that has just been washed. Places like fish and chip shops or McDonald’s cook fries in frying baskets. This allows the cook to lower the food into the oil more gradually, which reduces the initial splatter when the moisture first hits the oil. The basket also helps contain the food and makes the whole process safer.

This is also the reason water should never be thrown on an oil fire. Oils have something called a smoke point, which is the temperature at which they begin to break down and give off visible smoke. If the oil keeps getting hotter past that stage, it can eventually reach a temperature where it can ignite and catch fire. That is when there is a serious problem.

When water is thrown on a wood fire, it cools the burning material and helps smother the flames. With an oil fire, it does the opposite. Water is denser than oil, so it sinks below the surface instead of covering it. Once it sinks into the extremely hot oil, it almost instantly turns into steam. As already mentioned, water expands enormously when it becomes steam. That sudden expansion throws the burning oil upward and outward, creating a violent spray of fire. Instead of putting the fire out, it spreads it.

If there is an oil fire, the heat should be turned off if possible and the fire should be smothered. A fire blanket, a metal lid, or the correct fire extinguisher is the safest choice. A carbon dioxide extinguisher can work because it helps cut off the fire’s supply of oxygen. Smothering it with something that safely blocks the air can work too, but throwing water on it is one of the worst things to do. And this is what I learned today.

Sources

https://www.chowhound.com/1631946/why-hot-oil-splatters-stove

https://en.wikipedia.org/wiki/Smoke_point

https://www.dalepinnock.com/blog/cooking-oil-smoke-point-why-does-it-matter

https://en.wikipedia.org/wiki/Template:Smoke_point_of_cooking_oils

Photo by Klaus Nielsen: https://www.pexels.com/photo/woman-cooking-eggs-on-pan-6294432/

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Why do we get sleepy after eating? We get sleepy after eating because digestion, hormones, and our body clock can all reduce alertness, especially after a large meal. A lot of people notice that after a large lunch it becomes very difficult to stay awake through the afternoon, and the coffee starts to look more and more attractive. Eating does not always make us sleepy, though. It depends largely on what we eat, how much of it we eat, and what time of day we eat it.

Before researching this, I thought that the only reason we got sleepy after eating was because the body redirects blood from the brain to the digestive system to cope with the food we have eaten. However, if this were the whole explanation, we would get sleepy no matter what we ate, and that is clearly not the case. We also do not usually get especially sleepy after breakfast, even if we have eaten a very large one, so there has to be more going on. A person can feel perfectly fine after one meal and heavy-eyed after another, even if the amount of food is similar.

Blood being redirected is probably part of the story, but only a small part. When we eat, more blood is sent to the stomach and intestines to absorb nutrients and help the digestive system do its work. Obviously, the more we have eaten, the more work the digestive system has to do, but this by itself would not make us all that tired. The body is also shifting into what is often called a rest-and-digest state. The parasympathetic nervous system becomes more active, the body settles down to process the meal, and the whole system tends to become a little calmer. The main reasons seem to be more to do with the body’s chemical responses and with timing.

A lot of foods contain an amino acid called tryptophan. Our bodies use tryptophan to help make serotonin, which is a chemical messenger involved in mood, appetite, and sleep. Serotonin helps us feel calmer and more relaxed, and the brain also uses it as part of the process of making melatonin, the hormone that helps regulate the sleep-wake cycle. That does not mean that eating one tryptophan-rich food instantly knocks a person out, but after a large meal, especially one with a mix of carbohydrates and protein, this whole chain of chemical signals can contribute to that sleepy feeling. This is one reason why a heavy meal can feel so comforting at first and then so tiring not long afterward.

Carbohydrates can also play a part because they cause the body to release insulin. Insulin is made in the pancreas and helps move glucose out of the bloodstream and into cells, where it can be used for energy or stored for later. If a meal is very high in carbohydrates, especially refined carbohydrates, blood sugar can rise quickly and then fall again later. That drop can leave a person feeling tired, heavy, and sluggish. In other words, it is not that insulin itself is a sleeping chemical. It is that the body’s response to a large, carbohydrate-heavy meal can make energy levels dip afterward. Fatty meals can have a similar effect as well, simply because they are large, rich, and slower to digest, which can leave the body feeling even more weighed down.

Another reason we get sleepy is simply timing. Our circadian rhythm works with the light-dark cycle, and many people naturally have a dip in alertness in the early afternoon. This is why a large lunch often feels worse than a large breakfast. It is arriving right at the time of day when the body is already becoming a little less alert. A big meal can push that feeling further. That is one reason why a short nap after lunch, or a siesta, can make people feel better. Some light exercise after eating can also help. People doing physical work are probably less likely to notice the dip than people sitting still in front of a computer, because movement itself helps keep the body awake.

The best way to avoid getting sleepy after lunch is usually to have a smaller meal and not make it too heavy in refined carbohydrates. Some people also find it helps to include more protein, fiber, and vegetables rather than eating a very starchy meal all at once. However, the idea of having a small lunch and a large dinner is fairly recent. When many people worked on farms, lunch used to be their largest meal because they needed energy for physical labor in the afternoon and did not want to go to bed with a very full stomach. As countries industrialized and people moved from the countryside into cities, meal patterns changed along with work schedules and daily routines. These days a heavy lunch often comes before an afternoon spent sitting down, and that may be one reason the sleepy feeling stands out so much.

Sources

https://www.medicalnewstoday.com/articles/323379#prevention

https://www.healthline.com/health/food-nutrition/why-do-i-feel-tired-after-eating#Food-Fix-Foods-to-Beat-Fatigue

https://www.goodrx.com/well-being/diet-nutrition/tired-after-eating?srsltid=AfmBOoqYSMrleOhcvyGwvAwk6B7P4VHdYoRW2Y-fDlDAgCAYpyuilCaa

https://my.clevelandclinic.org/health/articles/22572-serotonin

https://www.caltech.edu/about/news/settling-debate-serotonins-role-sleep

Photo by Pixabay: https://www.pexels.com/photo/person-lying-on-sofa-269141/

The post #1658 Why do we get sleepy after eating? appeared first on I Learned This Today.

What makes us hungry or full? Hunger is driven by signals such as ghrelin, while fullness comes from a mix of stomach expansion, nerve signals, and hormones released by the digestive system.

Ghrelin is known as the “hunger hormone” because it is released when the stomach is getting empty and it is one of the main signals that tells the brain food is needed. It is produced mostly in the stomach, although the brain, small intestine, and pancreas produce small amounts of it as well. Ghrelin rises as the level of food in the stomach drops. There is no single trigger point. It just gradually increases. The hormone travels to the hypothalamus in the brain, where it stimulates Agouti-related peptide (AgRP) neurons. These are a specialized group of nerve cells that are major drivers of hunger and food-seeking behavior. The hormone reaches the brain and helps create the feeling of hunger. It also increases the desire to go and find food. It affects brain areas involved in motivation and reward as well, making high-calorie, energy-dense foods seem especially appealing.

Ghrelin does other things too. It helps the body manage how it uses and stores energy. It affects how quickly food moves through the digestive system. It also interacts with blood sugar control, insulin, and glucagon, showing that hunger is not just a simple feeling in the stomach but part of a much wider system that helps regulate energy in the body.

Ghrelin can also rise when people are stressed or sleep deprived, which is one reason stressed and tired people are more likely to snack. Things become more complicated in obesity and in dieting. People with obesity often have lower baseline ghrelin levels than leaner people, but the body’s hunger and reward systems can still become dysregulated. On the other hand, people who restrict calories often have higher ghrelin levels, which is one reason dieting can make hunger feel stronger rather than weaker. This is one reason it is often easier to say that appetite regulation has become disrupted than to point to one single hormone and blame that alone.

A feeling of fullness after eating comes from several different sources. The first is that ghrelin declines. Because ghrelin helps drive the sensation of hunger, that feeling starts to ease as its level falls. The second is the size of the stomach. The stomach has layers of tissue and muscle surrounding it. These muscles are folded into ridges called rugae. As food goes into the stomach, the brain signals the muscles to relax and the ridges slowly unfold. The stomach expands to accommodate what has been eaten. As it expands, nerves in the stomach wall send signals up the vagus nerve to the brain. This gives the brain information about how full the stomach is. As the stomach fills, the pressure increases and the brain sends stronger and stronger signals to stop eating. Anyone who has been at an all-you-can-eat buffet knows these sensations well.

There are several chemicals released by the digestive system that also tell the brain the body is full. Cholecystokinin is released by the small intestine when it comes into contact with fats and proteins. It slows the rate at which the stomach empties and strengthens the signals traveling through the vagus nerve. This is one of the first signs the brain gets that fullness is beginning. Then there are hormones called GLP-1 and PYY. They are released further down the digestive tract and they help suppress appetite after eating. GIP also plays a role, especially in insulin release and the body’s response to nutrients. Bile acids, which help break down food, can also stimulate the production of some of these hormones and signals. Finally, receptors in the digestive system and elsewhere help inform the brain about how many nutrients have been taken in and how much energy is now available.

The important thing is that hunger and fullness are not controlled by a single on-off switch. They are produced by a whole network of signals involving the stomach, the intestines, the brain, hormones, and nerves. If these systems are working well, the body will generally make us hungry when food is needed and make us feel full when enough has been eaten. The problem is that modern life can interfere with these systems. Stress, lack of sleep, constant access to food, and ultra-processed foods can all play havoc with the body’s normal signals. That may be one reason many of us now eat more than we used to, and more than we really need. And this is what I learned today.

Sources

https://www.forbes.com/sites/christopherthompson/2025/10/20/what-really-drives-hunger-and-fullness-the-science-explained

https://www.hopkinsmedicine.org/health/wellness-and-prevention/hunger-and-fullness-awareness

https://en.wikipedia.org/wiki/Ghrelin

https://my.clevelandclinic.org/health/body/22804-ghrelin

https://primalpictures.com/blogs/overeating-anatomy-physiology-stomach

Photo by Jonathan Borba: https://www.pexels.com/photo/assorted-mini-slider-platter-for-party-event-35247169/

The post #1646 What makes us hungry or full? appeared first on I Learned This Today.

What is Monosodium Glutamate? Monosodium Glutamate (MSG) is a salt used to add flavor to food.

MSG is the sodium salt of glutamic acid. Glutamic acid is an amino acid that occurs naturally in lots of foods, such as tomatoes, cheese, mushrooms, and seaweed. In foods, glutamic acid often loses a hydrogen ion and becomes glutamate. If glutamate pairs with a sodium ion, it becomes monosodium glutamate—a salt, like sodium chloride is a salt. In the mouth, MSG dissolves into sodium and glutamate; the glutamate triggers umami receptors, while the sodium adds a little saltiness. In small amounts, this can be a very delicious pairing and is why it is used to flavor a lot of foods.

MSG is a very desirable flavor, and it features heavily in Asian cuisine. Early ketchup and Soy Sauce both have high levels of free glutamate that are produced during the fermentation process. A lot of Japanese cooking uses seaweed, which is also high in MSG. Some Western cuisines were also high in free glutamate, although you wouldn’t think so. Italian food, such as pasta, is a very MSG-rich food because of all the tomatoes, cheeses, cured meats, and anchovies they use. All of these foods are very high in MSG and produce the umami flavor associated with a lot of pasta sauces. French cuisine also uses a lot of natural MSG.

Up until 1908, if you wanted the umami flavor you get from MSG in your food, you needed to cook with ingredients that had a lot of it. In 1908, a Japanese biochemist called Kikunae Ikeda managed to isolate the Monosodium Glutamate, and he also came up with the flavor name “umami”. He was eating broth for his dinner, and he realized that it had a much more delicious flavor than usual, which he associated with the kelp and flakes of fish in it. He set out to analyze why that might be, and that journey led him to the discovery of MSG. He called it “Ajinomoto”, which translates as “the essence of flavor”, and he went on to invent a way to mass produce it. He started the company Ajinomoto to market his new product, and that company still exists.

Depending on our diet, we eat a fairly large amount of MSG every day. Natural MSG is no problem, but there is a lot of added MSG in foods. Snacks like potato chips and other processed foods have added MSG to enhance their flavor. The general consensus has become that MSG is dangerous and unhealthy, but this is not actually true.

The idea that MSG is bad for you comes from something known as Chinese restaurant syndrome (CRS). People who eat a lot of Chinese food, which is high in MSG, sometimes end up with headaches, flushing, sweats, and numbness. It has become commonly assumed that this is to do with the MSG in the food. However, people who eat a lot of pasta, or other foods with MSG, don’t report the same symptoms. And double blind experiments have shown that people who eat a lot of MSG don’t report any symptoms. MSG in itself is harmless.

People who consume a lot of MSG are usually consuming a lot of salty, fried food, and also a lot of Ultra-Processed food. This might have more to do with their symptoms than anything else. As MSG is used as a flavoring in many types of Ultra-Processed food, it is easy to think that it is the cause. And, it turns out, Chinese Restaurant Syndrome was based on a letter that appeared in the 1968 New England Journal of Medicine by Dr. Robert Ho Man Kwok. This was speculative, unproven, and probably caused far more by racism than it was by a concern over MSG. Over time, the ‘Chinese restaurant syndrome’ label picked up a strong xenophobic edge, and many writers now describe the term as dated and offensive. Ajinomoto is currently attempting to get “Chinese Restaurant Syndrome” removed from dictionaries.

Just like any salt and any flavoring, if you eat it in natural foods, it probably does no harm. If you take it out of the food and eat too much of it, it may do harm. And if you eat a large number of snacks and ultra-processed foods that contain MSG, the MSG is probably not the reason why you are having health problems. And this is what I learned today.

Sources

https://en.wikipedia.org/wiki/Monosodium_glutamate

https://en.wikipedia.org/wiki/Kikunae_Ikeda

https://foodsafetyplatform.eu/knowledge/articles/what-is-monosodium-glutamate-and-is-it-bad-for-you

https://www.uvahealth.com/healthy-balance/msg-facts-on-monosodium-glutamate

https://www.bbc.com/news/world-us-canada-51139005

https://www.pearlriverbridge.com/breaking-down-the-nutrients-is-soy-sauce-healthy

The post #1604 What is Monosodium Glutamate? appeared first on I Learned This Today.

What is GM food? GM food stands for Genetically Modified food, and it means any food that is produced using some kind of genetic engineering to alter its DNA.

Generally, GM food refers to either taking a gene from one plant and inserting it into another or removing a gene that a plant already has. Inserting a gene is done because one plant might have a property that biologists would like the other plant to have. For example, sugar beet. We can get sugar from sugar cane and sugar beet. Not all sugar beet has been genetically modified, but some of it has been altered to be resistant to glyphosate, which is commonly used in herbicides. Herbicides with glyphosate are very effective at killing the weeds that plague sugar beet plantations, but that is no good if they kill the sugar beet as well. Glyphosate resistant genes were taken out of bacteria and added to the sugar beet, making it resistant and allowing for the herbicide to be sprayed. Papaya is another example. Papaya in Hawaii were being decimated by a virus called the Papaya Ringspot Virus. Scientists added a gene to the papaya that produces a protein that makes the plant resistant and defeats the virus. We eat GM animals as well. Scientists have taken growth hormones from Pacific salmon, added DNA from a different fish, and inserted them into a regular salmon to make them grow all year round.

Removing a gene is done to switch off a characteristic the plant might have that is not beneficial. An example of this is the Arctic Apple. This is actually a trademarked fruit. Scientists switched off the gene that produces polyphenol oxidase, which is responsible for making apples go brown. Now, thanks to that, Arctic Apples don’t go brown.

When a gene is added, scientists identify the gene that they want in another species and then remove it. That gene is then injected into the nucleus of a single cell of the target plant. They can only do one cell at a time, so once the gene has been added, the cell is cultured until it produces enough cells to produce shoots, and the new plant can be grown from these.

Genetic modification is not a new thing, but the speed and the way that scientists can now do it have changed. Ever since humans domesticated plants, we have been genetically modifying them. We do it by cross breeding different kinds of plants. If you have one plant and you want it to have the properties of another plant, you just cross breed them as many times as it takes until you get the change you want. And then you exclusively breed from that plant, which propagates the change. This is called selective breeding, but it is basically genetic modification, and all of the food we eat today has gone through this process. If you find wild vegetables, wild fruit, and wild grains, they are nothing like the ones we generally buy from our shops today. The difference today is that scientists can analyze what each gene does and then select or remove the ones they need to improve on the crop.

There are many arguments for and against GM food. Let’s try to look at a couple from each side. The first one in favor of GM is that it gives us better food and more of it. Fruit and vegetables can be made that are resistant to pests, longer lasting, and more nutritious. Crops that produce more are also possible. Without GM foods like this, we might not be able to feed a growing population. A second argument is that it is possible to make fruits and vegetables that can deal with our changing climate. As human made climate change gets worse, we need crops that can survive hotter weather and either more droughts or more floods. GM can make those kinds of crops.

An argument against is that everything we are doing is too fast, and it doesn’t give any time to check the side effects. When we selectively breed species, it takes a long time before the changes become apparent, and that can give us a long time to get used to it. The sudden changes that are possible now mean we don’t have enough time to detect any long term effects, and could be doing irreparable harm without knowing it. They could also harm the ecosystem because they may become inedible to animals. A second argument is that any GM crops can very easily cross pollinate with other crops, and their traits can start to spread to other plants. Whether we like or hate GM food, it is here to stay. And this is what I learned today.

Sources

https://www.who.int/news-room/questions-and-answers/item/food-genetically-modified

https://www.treehugger.com/gm-foods-commonly-found-grocery-stores-4858320

https://en.wikipedia.org/wiki/Plant_tissue_culture

https://en.wikipedia.org/wiki/Genetically_modified_food

https://www.sustainablemarketfarming.com/2022/05/25/which-vegetables-are-genetically-modified-gmos

https://en.wikipedia.org/wiki/Gene_silencing

https://en.wikipedia.org/wiki/Genetically_modified_sugar_beet

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