How does a pressure cooker work? By using high pressure to raise the boiling point of the water. Pressure cookers were invented in 1679 by a French physicist. He was trying to find a way to cook food faster. Cast iron pressure cookers were made in Germany in 1864. Pressure cookers improved through the early […]
#321 How does a pressure cooker work? Read More »
How does a refrigerator cool food? By transferring the heat from inside the refrigerator to outside using evaporation. Fresh foods have to be kept cool to make them last longer. As soon as they are opened, or cut, bacteria start to decompose them. When foods decompose, they taste bad, but some bacteria can produce toxins
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Why does metal spark in a microwave oven? The microwave charges one side of the metal positively and one side negatively. This charge can ionize the air, making sparks. First, we need to look at what microwaves are. A microwave is a type of electromagnetic radiation. Electromagnetic radiation is energy that moves in waves and
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It is olive oil that is made cold-pressed, without heat or chemicals. Olive oil has been used for thousands of years. Olives grow naturally around the Mediterranean and they were picked and eaten by Neolithic people about 6,000 years ago. Olives appeared in Asia Minor, which is where Turkey is today. The olive tree was
#312 What is virgin olive oil? Read More »
Is irradiated food safe? Irradiating food kills off all of the bacteria, gives the food a fresher taste than other preservation methods, and doesn’t make the food radioactive. Ionizing radiation was discovered in 1895. Wilhelm Röntgen discovered that rays coming off a vacuum tube could penetrate a screen and react with a barium solution. He
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Why does UHT milk last so long? UHT stands for Ultra High Treatment and it is heated at 138℃ for 2 seconds to kill all the bacteria. All milk you buy in the shop has been pasteurized. In most countries it is illegal to sell unpasteurized milk because of the dangers. Unpasteurized milk can contain
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When did people start eating cereal for breakfast? Technically in the 1850s, but it didn’t catch on until the early 1900s. The first breakfast cereal (albeit hot) was invented by Ferdinand Schumacher, a German immigrant living in America. He used a hand grinder to grind oats that he then sold for oatmeal. The oats were
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I learned this today. How does a desalination plant work? A desalination plant makes freshwater from seawater by using reverse osmosis. Humans and animals obviously cannot drink salt water. Fish have adapted to be able to do it, but we have not. There is about 35g of salt in every liter of sea water. If
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I learned this today. Instant coffee was technically invented in 1771, but this wasn’t really instant. Instant coffee that we would recognize today was invented in 1890. These days, instant coffee is coffee that has either been freeze-dried or spray dried. The two methods differ slightly, and freeze-drying is more expensive. When coffee is freeze-dried,
#277 When was instant coffee invented? Read More »
I learned this today. Hardtack is a dense biscuit made from flour, water, and sometimes salt. It was sometimes called “ship’s biscuit” because it was a staple on long voyages. The word “hardtack” comes from the British sailor slang for food, “tack”. It was called “hardtack” because it was extremely hard. Hardtack is a very
#262 What is hardtack? Read More »
