Why is the First Espresso Shot from a Coffee Machine Discarded? What is the Morning Calibration Process at Coffee Shops? What is the Purpose of Espresso Cleaning Powder?

It's well known that one essential task for coffee shops before opening for business is the morning adjustment of espresso. Because coffee beans are constantly changing, calibration is necessary to ensure that today's extracted espresso maintains the same delicious quality as yesterday's.

But did you know? The first espresso during the morning adjustment—the very first shot extracted after turning on the coffee machine—mostly ends up going down the drain! Why? Because it's most likely going to be thrown away!

Many might wonder why the first espresso shot needs to be discarded. Isn't it also extracted from coffee grounds using the coffee machine? Could it be because it tastes too bad?

Well, not quite! While its taste might indeed not be great, that's not the primary reason we discard it. There are actually three main reasons why we throw it away, and let FrontStreet Coffee break them down for you~

1. Residual Cleaning Powder in the Pipes

After a full day of use, the coffee machine's pipes are filled with coffee liquid that has been drawn in by the pressure release function. As water evaporates from this liquid, it forms scale that adheres to the pipe walls. If not cleaned promptly, this buildup accumulates over time, potentially affecting the coffee machine's performance. Therefore, we need to backflush the coffee machine using a blind basket and cleaning powder at the end of each business day to ensure the machine maintains long-term "health" (primarily our wallet's health).

Just like coffee liquid, cleaning powder leaves residue in the pipes that cannot be removed through simple water flushing. Therefore, during the next morning's calibration, we can use the extraction of this espresso shot to flush out the cleaning powder residue from the pipes—this is the main reason why we discard this particular shot. Of course, even if the coffee machine wasn't cleaned with cleaning powder the previous night, this first espresso would still likely face the same fate. Because, well, it probably doesn't taste good anyway.

2. Residual Coffee Grounds in the Grinder

As the name suggests, a coffee grinder is a machine that grinds coffee beans into powder. However, each grinding session leaves some coffee grounds residue inside the machine, both due to the machine's dosage limitations and because coffee grounds generate static electricity that causes adhesion. In short, coffee grinders always retain some amount of coffee grounds to varying degrees.

After coffee beans are ground into powder, carbon dioxide and flavor compounds dissipate quickly in a short time. Their loss not only results in extracted coffee with less rich and full flavor but also causes extraction parameters to become unreliable due to the changed state of the grounds.

For example, today's extraction target might be to extract 40ml of coffee liquid from 20g of grounds. If this coffee mixture contains residue from yesterday's grounds left in the grinder, the time to extract 40ml might be around 25 seconds. If using freshly ground coffee, extracting 40ml might require 30 seconds. Such a significant time difference would mislead our adjustment decisions, making this espresso shot of no value to coffee shops.

3. The Coffee Machine Needs Warm-up Time

Although the coffee machine's water temperature and pressure quickly reach their set values after turning on, these readings are not reliable immediately upon startup. For instance, the coffee machine at FrontStreet Coffee's store might display a water temperature of 94°C, but the actual measured temperature is around 80°C (normally it should be around 85°C). And then there's the pressure! After sitting idle overnight, the coffee machine's pressure pump enters a "sleep" state and cannot immediately deliver full performance during the first extraction after a long interval—it takes a while to reach the target pressure value.

Both water temperature and pressure are critical extraction parameters for espresso. Therefore, we need to "wake up" the coffee machine by extracting one shot, allowing it to immediately enter working condition.

In summary, we can conclude that the reason we discard the first espresso shot after turning on the coffee machine is due to the combined effect of these three factors! While there might be alternative solutions for each issue, why complicate things when extracting one espresso shot can solve all of them at once~

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前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473