When buying or storing Chenpi Pu-erh (Xiao Qing Gan), many people notice a layer of white substance on the surface and immediately think it's moldy. In fact, this white substance is usually called "White Frost" or "Citrus Oil Crystals" (Gan You Jing), and it is not only harmless but often a symbol of quality.
What is "White Frost"?
The white frost on the surface of Chenpi Pu-erh is similar to the frost on dried persimmons or preserved plums. It is a white powdery substance formed by the crystallization of rich citrus oils (volatile oils) that seep out from the peel after high-temperature drying or natural sun-drying during production.
- Cause: It is mainly related to the oil gland content, growth stage, and processing method of the citrus peel. Generally, citrus fruits from good origins with abundant oil glands and proper processing are more likely to form white frost.
Is It Safe to Drink?
Yes, absolutely. The main components of white frost are terpenes and alcohol compounds, which are essences naturally precipitated from the citrus peel. It is harmless to the human body and, to some extent, reflects the high oil content and excellent quality of the fruit. Therefore, there is no need to intentionally wash it off when brewing.
How to Distinguish "White Frost" from "Mold"?
Although white frost is good, one must be wary of true mold. You can distinguish them using the "Look, Smell, Touch" method:
- Look at the Color:
- White Frost: Appears as pure white frosty powder, distributed evenly.
- Mold: Usually appears as brownish-yellow, dark green, or grayish-black spots, possibly with mycelium.
- Smell the Aroma:
- White Frost: Smells of pure, rich citrus fragrance without off-odors.
- Mold: Emits a moldy, bitter, sour, or unpleasant musty smell.
- Touch the Texture:
- White Frost: Adheres to the skin and does not fall off easily (unless wiped hard); the peel remains hard.
- Mold: Mold may cause the peel to become soft, deformed, or even rotten, and mold spots fall off easily.
Summary: If your Chenpi Pu-erh has a uniform white frost and a pure aroma, please enjoy it with peace of mind; if there are strange colors or odors, discard it immediately.