How much does second grinding affect coffee and what does it mean?

　　We all know that coffee is best when it's freshly ground and brewed, but when you get a gift of coffee powder, if it's a packet of medium-coarse powder, you may want to take it back to a fine grind, and then use the second-degree ground powder to make espresso.
　　
　　Regrinding may clog the grinder
　　
　　This is the most important point. If you put the coffee powder back into the grinder and grind it to a finer grind, the powder will not fall through the grinder's blade as smoothly as the beans, and not only will you not get the fine grind you want for your espresso, but it will also cause more powder to be left in the grinder's blade, which will contaminate the quality of the grind later on.
　　
　　In order to remove this powder residue and restore grind quality, you must also disassemble the grinder and clean the blade thoroughly. Many grinder manufacturers don't recommend disassembling the machine yourself, and may not even offer a warranty, which is no fun when you can't go back to your original state and you want to drink coffee.
　　
　　In addition, these second-degree grinding powder, in fact, is not suitable for espresso, can only be used for composting, deodorant and coloring agent and other purposes, because such a state of the powder will be too fine, resulting in the flow of water can not pass through the coffee powder to achieve the purpose of extraction.
　　
　　Even if you have a way to adjust the grinder, in the premise of not contaminating the blade, but also can grind just the right size, these re-ground powder can not be brewed full-flavored concentrated, the key is in the aroma. Once the coffee is ground, the aroma will be released in large quantities, and then the coffee flavor can be maximized through proper brewing. When you get ground coffee, even if it's ground again, it's already a powder that has lost a lot of its aroma by the time it's brewed.
　　
　　That's why we recommend grinding the beans before brewing, and it's best to brew the powder in less than five minutes. When you grind the coffee powder beforehand, even if you put it in an airtight canister or in a vacuum, the coffee that comes out of the brewing process will still be a cup of coffee that has lost a lot of its aroma, and won't be too tasty.