Why would you spend $1 on ice? Let us reveal the secrets behind the ice cup
This year, ice cups have become popular. Although “ice cubes in plastic cups” seem to have no technical content, most of them are sold at prices higher than bottled drinks, but this has not prevented the hot sales of ice cups.
Some people can’t help but ask, “Buy ice for $1? Why not freeze it yourself?” Let’s try to interpret the secrets behind ice cubes.
Is it just a matter of time before ice cups become popular?
Commercial ice cups have not been popular in China for a long time. The annual sales of the well-known brand Binglida were only 1 million cups before 2022, but it jumped to 50 million cups last year. The main sales channels are convenience stores and shopping malls.
Starting in 2023, brands in other fields such as Nongfu Spring and Aoxue have launched ice cup products, and with the sharing of recipes on social platforms, a wave of DIY ice drinks has been triggered. Coffee, sugar-free tea, milk, and juice are all colliding with ice cups, and they are summer special drinks for young people.
From now on, in addition to air conditioning, watermelon and WiFi, “ice cups” have also become a place for summer. This trend is not new to our neighbors. Ice cups in convenience stores in Japan and South Korea can sell over 100 million in July and August alone. Koreans love ice all year round, and ice cups are always the top two best-selling products in convenience stores.
Huge sales have driven product upgrades. The form of ice cups in convenience stores in Japan and South Korea is still evolving, and is no longer limited to the concept of “cup”: ice boxes, ice buckets, with lids/without lids, double straws… In China, where people drink hot water all year round, everyone’s consumption habits are gradually changing, and more and more people are eager to enjoy ice cubes anytime, anywhere.
This is one reason why ice cups are popular, but what is the difference between ice cubes produced by commercial ice makers and those frozen in your own refrigerator? What kind of ice can be called “good ice”?
What kind of ice melts slowly?
When it comes to paying for ice, “melting slowly” is obviously the most important core value point.
While Luckin Coffee and other tea and coffee brands have been criticized by consumers for “half a cup of ice”, they have also won the favor of some people: after drinking, the remaining ice in the cup can be reused and poured into other drinks to make a brand new ice drink.
So, what kind of ice melts slower, and how can we judge?
The most intuitive way is to look with the naked eye, whether the ice is white or transparent.
In most cases, the water used to freeze ice is not pure enough, and the most common “impurity” is the air dissolved in the water. When making ice in the refrigerator yourself, as the water in the ice tray cools down and condenses from the outside to the inside, the small bubbles in the water will be “forced” to the middle of the ice, and eventually have no way to escape.
These bubbles and other impurity particles are trapped in the ice, forming many tiny gaps, scattering light at various angles, and the ice looks white. These gaps not only affect the appearance, but also accelerate the melting of ice: freezing and melting of ice are actually the process of heat conduction. The more gaps in the ice, the larger the contact area with the outside world, which helps heat conduction.
The higher the purity of the water, the fewer gaps there are in the frozen ice, and the more transparent the visual effect is. When making homemade ice cubes, it is better to use boiled water, because the boiling process can reduce the air content in the water. Commercial ice making uses water that has been filtered of impurities, and removes as much air as possible during the processing process, eventually forming high-purity “special ice”.
Common sense in physics tells us that under normal circumstances, the melting point of a mixture is always lower than that of a pure substance. In life, we can also see that sprinkling salt on icy roads in winter can accelerate ice melting, that is, the more impurities contained in the ice, the easier it is to melt. If you want to enjoy the icy taste for a long time, you must try to reduce the impurities in the ice.
In the preparation process of professional edible ice, tap water is often filtered in various ways, including RO (reverse osmosis) membrane filtration, which can basically remove any impurities, and then the “flowing water slow freezing” method is used to squeeze and freeze the pure water layer by layer to create ice cubes with purity and density that crush the homemade ones.
In addition, the finished product temperature of ice made by professional production lines is also relatively lower. For example, the refrigerant R404A commonly used in ice machines has a standard evaporation temperature as low as -46.5℃, while the temperature of the freezer of a household refrigerator is usually set at -18℃, so the temperature of the ice cubes produced is obviously higher.
Unless you have good patience and keep the ice cubes in the freezer for a long enough time, the ice cubes will eventually reach -18℃, which is comparable to the temperature of professional edible ice.
The size and shape of the ice cubes themselves will also affect the melting time.
As we all know, the larger the ice cubes, the slower it melts, because the specific surface area (the ratio of surface area to volume) of large ice cubes is lower. In layman’s terms, if a large piece of ice is cut into several small pieces of ice, it is equivalent to increasing the area for heat conduction with the outside world under the premise of unchanged volume, which will naturally accelerate melting.
Under the premise of the same volume, the surface area of spherical objects is the smallest, which can delay heat exchange and melt slower than square and irregular ice cubes.
GS25, a leading convenience store in South Korea, launched the big ball ice cup, which contains only a baseball-sized round ice cube. It claims that at room temperature of 23°C, the ice ball takes 70 minutes longer to completely melt than an ordinary ice cup, and it quickly became a hot seller.
In addition to the ice cube itself, the area it contacts with the liquid also affects the melting speed to a certain extent. The thermal conductivity of water is much higher than that of air, so at the same temperature, ice melts faster in water.
The raw materials of drinks such as milk tea include milk, tea, sugar, etc. The density of liquid is greater than that of water. Ice cubes soaked in milk tea are more likely to float to the surface, so they melt slower than those soaked in water.
There are so many secrets hidden behind the small ice cubes. Do you think that the $1 ice cup is more worthwhile now?
Keywords:ice cubes , Commercial ice, commercial ice makers