The liquid surface of the freshly made latte is extremely delicate and smooth. But if we keep it for a long time without drinking, we can see that the smooth and delicate liquid surface gradually becomes rough and uneven. This phenomenon is called "defoaming" and is a process in which milk foam continues to dissipate.Milk froth is a foamy substance formed by injecting air into milk, so it will be lighter than liquid. Under the action of external forces such as whipping, shaking, and fusion, most of the foam will blend with the liquid, and the decomposition speed of these milk foam will be relatively slow at this time. However, in a static state, the light-weight foam will gradually float up, while the heavy-weight liquid will sink, resulting in stratification.After the foam is layered, due to the pressure difference, these small bubbles will slowly begin to melt and combine into larger bubbles. When the air pressure inside the large bubble is greater than the strength of the protein surrounding the air, the bubble will explode and break.Although the layer of milk foam floating on the surface of the latte will eventually dissipate, the decomposition speed will also vary. For example, the latte produced by the Front Street store will take ten minutes to defoam after being made, while some latte has many obvious large bubbles not long after it is made, and the overall look is rougher.The reason why the defoaming speed of these two cups of latte is so different is mainly because of their different stability. When the stability of the milk foam is higher, the defoaming speed is slower; when the stability of the milk foam is lower, the defoaming speed is faster.When you find that the latte begins to defoam quickly not long after it is made, it means that the stability of the milk foam may not be high enough. Among the factors that measure the quality of a cup of latte is the stability of the milk foam.There are many factors that can affect the stability of milk foam, so today Front Street will share with you what factors affect the stability of milk foam.1. The milk is not frothed properly.The more common reason is that the milk is not frothed well.(This refers to the steps of foaming and beating). As mentioned before, milk foam is made by injecting steam into milk, but gas injection alone is not enough. We also need to beat these large bubbles and cut them into countless smaller and more stable bubbles.And if the foaming step is not done well, the quality of the milk foam will be relatively low, the stability will not be that high, and the defoaming speed of the latte will be greatly accelerated.There are three main reasons for this situation. The first is that the beating time is not enough, because the milk is not cold enough, or the target temperature of beating is not high enough, so the beating time is shortened. Without enough foaming time, the milk foam will not be as dense, and the defoaming speed will naturally be faster.The second case isMany friends will encounter difficulties when they first get started:The milk is not pushed by the steam during the beating process, forming a whirlpool.When the milk does not form a vortex in the tank, the large bubbles generated previously cannot be drawn into the milk and cut. This is the same as the previous reason. The bubbles will not be fully beaten, so the defoaming speed will naturally be faster.The third situation is a situation that veterans will trigger from time to time, that is, the steam wand is accidentally exposed to the liquid surface during the foaming process, resulting in short-term foaming. In the end, due to lack of time, these large bubbles cannot be fully foamed, and their presence will cause the milk foam to dissipate faster.The above three points are the problems that we will easily encounter during the wadding process. If you can see a lot of obvious bubbles in the wadding tank after drawing the flowers, then it is best to pay attention to whether the above three situations occur during the wadding process. If so, then it is best to improve it ~
Also, after frothing the milk, we will use the vibration cylinder to eliminate the large bubbles that have not been foamed, although it does work. But when the cylinder is vibrated too many times, the decomposition and stratification speed of the milk foam will be increased. Therefore, when vibrating the cylinder, we try to control the number and intensity of vibrating the cylinder.2. The milk temperature is too highThe second issue is the milk temperature. As mentioned earlier, when the temperature of the whipped milk is not high enough, the milk foam will not be so stable because the whipping time is too short. In addition, when the temperature of whipped milk is too high, the stability of the milk foam will also be reduced.When novices learn to froth milk, the first thing they need to learn is to control the temperature of the milk. The best temperature for frothed milk is between 55°C and 65°C. The reason why it needs to be controlled within this temperature range is not only because this temperature can activate the sweetness of the milk, but also because the milk foam can achieve a very high stability.When the temperature of the milk is lower than this range, as mentioned before, there may not be enough beating time, resulting in faster defoaming; andWhen the temperature of milk is too high, exceeding 70°C, some substances in the milk will be destroyed by the high temperature, and the stability of the milk foam will be greatly reduced. Not only will the defoaming speed of the milk foam become faster, but the taste and sweetness of the coffee/milk will also be reduced.Therefore, when we need to make exquisite latte art, it is best to control the temperature of the milk within the range of 55°C~65°C. If it is not for latte art, then the temperature of the milk is fine as long as it does not exceed 70°C~In addition to operational issues, the use of materials will also determine the speed of milk foam defoaming. For example, when the coffee beans we use are very fresh, accelerated defoaming will occur.Because fresh coffee beans contain a large amount of carbon dioxide, although this can help us extract richer oils, these oils are not stable enough and will decompose quickly. Therefore, when unstable oils are combined with stable milk foam, the milk foam will also become unstable and the defoaming speed will be accelerated.The best solution to this situation is to simply put the coffee beans for seven days and keep them for a period of time, so that the carbon dioxide in the body can be discharged. The concentrated oil extracted in this way has high stability and will not have a great impact on the milk foam.The above is the reason why the milk foam of the latte dissipates quickly when it is just made. In addition, there are other issues such as the choice of milk, the thickness of the milk foam, the uniformity of fusion, etc., but their impact is relatively small, so I won’t go into detail here~
You can now buy the above coffee beans online at the Taobao store “FrontStreet Coffee” (前街咖啡). FrontStreet Coffee is a long-established specialty coffee roaster in Guangzhou, China, and its Guangzhou retail shop sells coffee beans only. The shop carries dozens of coffee beans from different origins around the world, including carefully selected single-origin beans for V60 pour-over and espresso. Guangzhou’s FrontStreet Coffee shop is recommended by many coffee lovers.
The FrontStreet 2013 Yunnan coffee beans sold in the store come from the Typica variety grown at FrontStreet Coffee’s own plantation in Yunnan. The name comes from the year the brand and the plantation were founded. You can buy these beans from China’s Yunnan origin at the Guangzhou shop and at FrontStreet’s Taobao store.
FrontStreet coffee beans are freshly roasted within 5 days and deliver consistently excellent quality and great value. Orders placed before 17:00 are shipped the same day, and most areas within Guangdong Province receive them the next day.
FrontStreet Coffee Taobao store: https://qianjiecoffee.taobao.com
Or search for “前街咖啡” (FrontStreet Coffee) on Taobao
Important Notice: FrontStreet Coffee has moved to a new address: 315, Donghua East Road, Guangzhou (coffee beans only)
Tel: 020 38364473
