This question originally appeared on Quora. 
By Peter Baskerville, Founder of 20 Cafes and Food Businesses
I would say there is one key area that separates the good barista from a great one - Doing everything possible to create the 'god shot' in every cup of espresso.
The 'god shot' is perfectly extracted espresso coffee that is used as the base for whatever variation of coffee beverage the customer has ordered Coffee: What are all the different types of coffee drinks?
A great barista knows that a 'god shot' is no guarantee, even in a perfectly set up espresso workstation. This is why you can get different espresso quality from the same cafe depending on who makes it ... a good barista or a great one.
See, there are just so many variables that all impact on the quality of espresso extraction. There is the coffee equipment of machine and grinder: the coffee blend, roast, granularity, volume, freshness, resistance (tamper): the water temperature and pressure: the portafilter seal, cleanliness, and fit: the speed of starting, ending extraction: and beverage serving time
A great barista seeking the 'god shot' can be soon recognized by the following actions:
- First, they will most likely be standing behind an Italian designed and built three or four group espresso coffee machine accompanied by a commercial grade conical grinder incorporating its mortar and pestle grinding action.
- You will often catch a great barista cleaning the buildup of taste spoiling burnt coffee oil that accumulates on the back of the filter and inside the portafilter caused by coffee oils that get trapped and baked onto the portafilter due to the high temperatures at the grouphead.
- A great barista knows their clientele well. They know the discerning customers who have an educated espresso palette and will reach for the single group to make your espresso, rather than let your cup be made by the more standard but lesser quality of half a double group.
- When they remove the portafilter from the espresso machine and release the used coffee cake into the bin, they will wipe the filter basket dry and remove all traces of previously spent coffee grains - especially from the rim of the portafilter, which may have become caked on.
- You will see them flush water through the shower-head to remove spent grains and to set the temperature at the shower-head at the optimum level for perfect essence extraction. You may even see them pick up a blind filter and backflush the shower-head and rim to ensure that even the caked-on coffee grains on the pressure ring are removed and do not detract from the potential to make this cup the 'god shot.'
- They take great care to ensure that the full measure of the prior determined volume of ground coffee from the coffee grinder hopper makes it into the portafilter. You may see them add a small amount of coffee grounds because they know the importance of a perfect resistance to extracting the perfect essence, and the little extra may have been deemed necessary based on their observation of previous cups.
- You may hear the grinder working as they prepare your coffee because they want the freshest possible ground coffee, perfectly tampered and inserted into the coffee machine without delay because they know that the most delicate and desirable aromas of the 800 found in espresso coffee are lost in the few minutes of exposure to grinding and the ambient air.
- They will add extra pressure to the portafilter's engagement with the espresso machine to ensure a perfect seal, so that the full ten bar pressure of the pump is brought to bear on the perfectly packed ground coffee cake created by the multiple variant grind of the conical grinder.
- A great barista is always mindful of the key gauges on the espresso machine. They won't start or will abort the process if they see the boiler pressure sitting below one bar and the pump pressure does not immediately reach nine bar once extraction is commenced. Without these key gauges registering the proper setting, the perfect extraction is impossible.
- Then, no matter how friendly and chatty a great barista may have been to this point, something far more important will totally command their attention for the next 18-25 seconds ... watching the speed, color, texture, and shape of the espresso extraction. Having done everything possible to create the perfect shot, a great barista becomes totally engrossed in the moment to see if these particular fifty or so random ground roasted beans, hand picked from the slopes of some equatorial country become that illusive 'god shot' that they incessantly seek.
- A great barista knows the perfect time to finish the extraction where the total available flavors of the ground coffee have been extracted, yet seconds before the tanic acid has had a chance to breakdown from coffee shell and leach into and destroy the cup with its bitter, burnt, and astringent aftertaste.
- Furthermore, when you see the barista at this point put aside a cup and restart the process, you know they are great. A great barista can accurately rate an espresso coffee taste purely on the look and form of the extraction and can not bring themselves to serve anything less than a 9.5 out of 10. When a great barista tells you that you have a great cup, don't dismiss it as promotional hype ... they are simply passing on the facts of what they witnessed in the extraction process.
So next time you see these busy actions happening behind the coffee machine on your behalf, don't complain about the time taken or the sometimes dismissive attention given by the barista or the seemingly excessive actions taking place to make your beverage ... because just maybe, you are the one that the gods of nature are wishing to favor today with the 'god shot,' expertly crafted by a great barista.
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