Do you prefer iron cakes or bubble cakes?
Is there really a comparison to be made here? Iron cakes are sports equipment used for throwing, while bubble cakes are something you eat!
No, no! The iron cakes and bubble cakes we are referring to here are not what you might think. They refer to two different forms of Pu'er Tea cakes that result from different pressing methods.
“Steamed and formed into tight cakes.” Why do Pu'er teas need to be pressed instead of stored loose? This is a basic question. Pressing Pu'er tea into cakes, bricks, and tuos initially served to make storage and transportation more convenient. By compressing the tea, it takes up less space, significantly reducing transportation difficulties, while also preserving the flavor and aroma of the Pu'er tea to the maximum extent possible.
Within the category of tea cakes, there are iron cakes and bubble cakes. But why is this so?
What are iron cakes and bubble cakes?
Famous essayist Yu Qiuyu is a loyal supporter of Pu'er tea and an expert in tasting aged Pu'er teas. His article “Tasting Pu'er Tea” expresses his understanding and appreciation of Pu'er tea from a literary perspective. Based on his own tasting experiences, Yu Qiuyu ranks his top five teas for various categories, including registered teas, printed teas, and seven-son cakes. These rankings have provided significant reference value for many tea enthusiasts when tasting Pu'er tea.
In his ranking of printed teas, the top five are: Large Red Seal, Grade A and B Blue Seals, Red Seal Iron Cake, Paperless Red Seal, and Blue Seal Iron Cake. Two of these are “iron cakes.”
The term “iron cake” refers to Pu'er tea cakes directly pressed into shape using metal molds. Because of the mechanical pressure, the tea cakes are very tightly compressed and hard like iron, hence the name.
Iron Cake
To press an iron cake, the steamed tea leaves are not placed in a cloth bag but directly into a metal steaming basket. After being steamed, the tea is pressed directly into a metal mold, resulting in a compact cake that is then removed. Iron cakes have straight edges and a rigid appearance, making them harder than regular tea cakes. They are difficult to break apart and have a “sturdy” look, which helps preserve their aroma.
If tightly compressed Pu'er tea cakes are called iron cakes, how should we describe those that are more loosely compressed? The prefix “bubble” is thus used, leading to the term “bubble cake.” Bubble cakes are formed using cloth bags and traditionally pressed with stone mills. Bubble cakes have a slightly raised surface and a small indentation on the back, with clear tea strands and a relatively loose internal structure, making them easy to break apart. Compared to iron cakes, bubble cakes appear “softer and gentler.”
Bubble Cake
Anecdote about Iron Cakes
In the 1950s, influenced by innovations in manufacturing, tea factories responded to national calls to improve tea production techniques, attempting to replace cumbersome manual operations with machinery. In the mid-1950s, metal molds appeared but were only tested, without formal production. In the early 1970s, machine-pressed molds began to produce tea cakes. Without using cloth bags, the cakes produced had flat bottoms and straight edges, significantly different from traditional mud loach-shaped edges. They became known as “even-edged” seven-son cakes.
Mechanical pressing is entirely different from human pressing, resulting in cakes that are much more tightly compressed. Machine-pressed iron cakes were difficult to break apart and age, and they did not receive consumer favor when introduced to the market. Consequently, production was not continued. However, over time, people gradually discovered the advantages of iron cakes, leading to the resumption of production. Today, the production process of iron cakes has been continuously improved, making this special tea product an interesting anecdote in the history of Pu'er tea.
Iron cakes are a unique presence in the production of Pu'er tea, representing the historical evolution of a tea product and the advancement of production technology. Over the years, iron cakes slowly transform, and after proper dry storage, waiting becomes their most brilliant value.
About brewing
The brewing methods for iron cakes and bubble cakes are similar, with the main difference lying in breaking apart the tea. Due to the use of metal molds for compression, iron cakes are extremely hard. If you want to immediately break apart the tea cake for brewing, it is very difficult to do so in chunks; often, it breaks into fragments. When brewed, fragmented tea produces more sediment and a rougher taste, lacking harmony. On the other hand, brewing an entire cake can be challenging, causing problems for tea enthusiasts who wish to promptly taste the tea.
In reality, tasting an iron cake requires great patience. First, use a metal tea knife and gently insert it along the edge of the tea cake, using the knife to separate the surface layer of the cake. During the process of breaking the cake, try to follow the gaps and natural lines of the tea leaves, allowing you to break the cake more intact and avoid breaking it into smaller pieces.
When brewing tea, if using a Gaiwan, preheat the utensils with boiling water at 100 degrees Celsius. Ensure the utensils are thoroughly heated to help release the aroma and facilitate the smooth extraction of the tea's inner contents. If brewing with a purple clay Teapot, pour boiling water into the pot and then circle the outside of the pot with additional hot water to maintain the temperature. Additionally, pay attention to the thickness and height of the water stream, allowing the tea leaves to gently turn, facilitating the blending of the tea liquid and the best expression of the tea's flavor and character.
Adjusting the thickness of the water stream and the pouring method can also subtly adjust the texture and aroma of the iron cake during brewing. With a bit of attention during the brewing process, experience will quickly build, allowing you to appreciate the unique taste of iron cakes.
About Storage
Among the various types of Pu'er tea, iron cakes are a relatively unique form. After being pressed into iron cakes, the internal space between the tea strands is very compact, with minimal contact area with air. Factors such as moisture, temperature, oxygen, and light in the air have little effect on the tea cakes. The tea inside cannot come into contact with large amounts of moisture in the air, slowing down the transformation process, which is roughly twice as long as that of bubble cakes. As a result, they are better suited for long-term storage.
The microorganisms in iron cakes can be better preserved, and the slower oxidation process allows the tea quality to be better preserved. The slow aging process gives iron cakes a unique taste and character.
By contrast, bubble cakes are more loosely pressed, with the internal tea strands having greater contact area with air. They can absorb more moisture and oxygen from the air, and the ambient temperature has a significant impact on the tea cakes, leading to faster transformation. Therefore, the fermentation is more comprehensive, making them suitable for short-term storage. Additionally, in terms of regional suitability, bubble cakes, being more loosely pressed, are better suited for storage in dry and cold northern regions, while iron cakes, being more tightly pressed, can be stored in humid and warm southern areas.
Of course, whether it is iron cakes or bubble cakes, appropriate storage is essential, requiring dry storage and protection against dampness and unwanted odors.
Originally published in Pu'er Magazine
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