Xinhua
Xinhua
Shizuku
In the middle of the day, you'll have to eat some ice cream. Do you ever wonder why ice cream tastes so amazing? The ice cream is also obviously more delicious than the normal popsicles. The process of making ice cream, which used to be full of many wonderful physical, chemical and even ore formation processes, plants and animals resistant to cold and forest regeneration patterns, is inextricably linked。
The ice cream microstructure is no different from granite
Ice cream is actually made up of ice cream, cream and air. It's sweet and refreshing, soft and lubricating. Among them, water accounts for 60-72 per cent of the total quality of ice cream, although they exist in the form of small crystals. In addition to this, only 8-10 per cent of ice cream is delicious oil and another 25-50 per cent is air。
The size of the ice cream is a key factor in making ice cream smoother. If the crystal is too big, it tastes like a chew of ice, much bigger, and ice cream becomes ice cream. Only small crystals, small enough to be cell size, can produce a smoother taste。
So what are the conditions for water to condensate into such small crystals
Look at some rocks first. Rocks consist mainly of minerals such as quartz (silicate dioxide), and ice and quartz are crystals, so if you look at the microstructure of ice cream under a microscope, you see that it is not very different from a granite structure formed after the cooling of the earth's magma。
When hot magma reaches the surface, the faster it cools, the smaller the size of the mineral crystal in the rock. For example, lava derived from a direct volcanic eruption can rapidly form volcanic rock, often containing very small mineral crystals. So to get a tiny crystal, you can cool it fast。
The principle of liquid nitrogen ice cream, which is now popular, is to speed up the freezing process and make the crystal as small as possible. The traditional method of making ice cream, the crystal can only reach a few μm scale, while the liquid nitrogen of 196 °c can be used to make ice cream, so the internal crystal can reach a few nanometer scale。
Now you know why we can't make delicious ice cream with our own refrigerator, and we'll have to freeze a big block of ice。
Zero-two, which is the same as the forest regeneration process
Of course, the method of obtaining tiny crystals is not just one of fast cooling。
In the ice cream production process, the first step is called dynamic freezing, i. E. Mixing and freezing. In the process, crystals will gather around the inside of the mixer, which will quickly scrape the inside of the wall and mix it with other ice creams. - the time between scratches is very short, only 0. 1 seconds. It's a quick operation to prevent crystals from growing up。
More than that, scraped crystals can become new crystal cores that other water molecules can attach to more crystals. As a result, the number of crystal cores in ice cream is increasing, the number of water molecules is decreasing, and a large number of crystal cores compete for limited water molecules, with the result that the crystal core has no chance of growing into ice。
This process is very similar to the logic of forest regeneration。
When forests are invaded by external forces, such as human logging, a wildfire or a hurricane, many trees disappear, the forest leaves a vacant spot, the new tree seedling grows, but the limited resources that this small piece of land can provide will grow very slowly, as if it were a scraped crystal. Only strong seedlings can grow back into big trees。
By the same token, creating “water molecule competition” makes crystals difficult to grow up, which is the key to making ice cream silky。
Ice cream with a life-guard for cold plants and animals
Have you ever tried to buy ice cream in three volts, which may melt during transport, reconcrete it in the fridge, then take it out and eat it。
In fact, ice cream is "fresh." in the course of transport, ice cream crystals melt hotly and then condensate into larger crystals, resulting in ice cream that is hard like a popsicle。
In fact, every time you open the fridge, the ice cream in the fridge melts a little bit, and after a couple of times, their taste drops. In order to ensure their taste, people add stabilizers to ice cream, slowing the movement of liquid water molecules in ice cream mixtures, and keeping ice cream stable for long periods of time。
And those who live in cold wildlife are already using this “stabilizer”。
Plants and plants living in a very cold environment with temperatures below zero degrees celsius, in order to remain free of ice, usually contain an anti-frozen protein that is adsorbed to the ice nuclei and prevents the concentration of water molecules so that the crystals cannot continue to grow and organisms can avoid the misfortune of low-temperature cell damage or even death。
Anti-frozen proteins were initially found in fish in polar ice water, and it was later found that it could also be synthesized in laboratories with genetically edited yeasts. Today, anti-frozen proteins are used as food additives for ice cream。
04 physico, chemistry in formation
The main ingredients of ice cream are butter, butter from milk in addition to water. But we know that oil and water cannot dissolve each other, and even when mixed together, they can be tiered quickly. But why is the water and grease in ice cream so perfect? The answer is still in the microstructure of ice cream。
The oil and vinegar that is commonly used in blunders consists of three oils and one vinegar. Oil and vinegar were not soluble in the first place, but if they were mixed together, the oil would eventually break into tiny spherical droplets, spread evenly into the vine and form emulsions. Emulsion is an even mixture formed by two insoluble liquids, most of which are unstable and long-placed, or are layered. But there are also stable emulsions, such as milk and coconuts, which can remain mixed for as long as they wait. This is because the milk contains natural emulsified proteins, which have a molecular structure that is watery and oily, which reduces the surface tension between the oil and the water and wraps a small droplet in it, making it difficult for them to gather, and which appears to be soluble in the water。
However, natural milked proteins in milk alone are not enough to keep ice cream stable for a long time. In general, additional emulsifiers, such as egg phosphorus and cheese protein, are added to make ice cream to help water and grease in ice cream to maintain more stable emulsions. Pyrophosphate is not only a good emulsifier but also a blowing agent。
The volume of air in ice cream can usually be 25-50 per cent, so that it can taste more loosely. Similar to emulsants, blowing agents can reduce surface tension of liquids and make air more susceptible to being wrapped up in liquids. So, the bubbles in ice cream are like a bunch of little soap bubbles frozen。
There's an interesting "cold knowledge": ice cream can exist at a maximum altitude of 3,000 meters. Because above this altitude, the bubbles in ice cream expand and break because of low atmospheric pressure, and in the end the whole ice cream collapses to half its size, becoming a hard frozen cream mixed with ice。
And finally, to borrow a sentence from feynman's physics: the whole universe is in a glass of wine. He said, "if we look at a glass of wine with enough detail, we can see the universe. It is divided into several parts: physics, biology, geology, astronomy, psychology, etc., but nature does not know all this.” perhaps we can also say that there is a universe in an ice cream。
