Getting your coffee out of hot water
This is one of those challenging issues that coffee purists will hate but which in reality occurs over and over again in many a foodservice outlet. The coffee machine temperature/pressure (they are interlinked) is set a little too high or has increased over time.
I can already hear the clamour for “get an engineer in” however I see this issue on so many occasions, particularly with low spec commercial coffee machines that I now find it easier to look for alternative solutions.
When water is over temperature; that is above 92 degrees Celsius the result can be a horribly over-extracted cup of coffee. Lots of flavours that were never intended for your taste buds appear in all their appalling glory. That great coffee your local roaster has so lovingly prepared becomes undrinkable.
Unlike black tea, coffee likes to be treated gently. Whereas tea leaves love boiling water to get the brew moving, the best coffees need to be coaxed into delivering those fine sophisticated notes. So in the real world how can the coffee be manipulated to ensure at least a half-decent result?
The constant I remind you is overly hot water. That means there are two things we can change. The contact time between coffee and water and/or the coffee.
In the industry, a shot of espresso coffee should have an extraction time of anything between 25 and 35 seconds (I’m avoiding grammage of coffee and pump pressures so as not to overly complicate this blog) as with everything in life there will be exceptions however this is a good rule of thumb.
Although not ideal a partial solution to over-extraction is to coarsen the grind of the coffee. This will have the effect of reducing contact time between water and coffee and give less time for the nastier flavours to escape into your cup. You will lose depth of flavour but at least you might have something that a paying customer will be satisfied with.
Another alternative is to look at the type of coffee you are using. Not whether it’s a big name brand but whether the roast level, process type or varietal is able to deliver an appropriate flavour in these challenging conditions.
Roast levels go anywhere from light, medium to dark. The lighter the roast the higher the levels of acidity in the coffee and overly hot water will only emphasise that acidity. So going towards a darker roast coffee can help improve quality.
By process type, I’m referring to how the coffee has been prepared at origin. Washed coffees will have higher acidity levels than semi-washed or naturals. However, naturals can get overly fruity in nature. My preference would be for semi-washed, that is where the coffee after pulping is dried with its mucilage still intact. This process tends to deliver a little more sweetness in the coffee.
Finally varietal, here I’m referring to Robusta coffee as opposed to Arabica coffee. Ignore all the rubbish spoken about Robusta coffee as being low grade and not worthy of darkening the doors of the latest and trendiest coffee shop. There are some truly great Robustas out there, particularly from southern India. They have a more gentle, slightly earthier nature to them than Arabicas and can withstand a lot of abuse in a coffee shop environment. Take a look at the possibility of getting some robusta coffee into your blend. You will find acidity levels drop and you’ll get a decent cup of coffee to boot for which people will pay money.
If you don’t want to put your favourite coffee roaster under this much stress, call out that engineer