Missing crema is usually bean age. Crema is carbon dioxide released during roasting, held in the bean and emulsified during extraction, and beans lose it steadily from the day they are roasted.
Freshness first. Beans rested seven to twenty-one days after roast give the best crema. Under three days they can be volatile and gassy, over eight weeks the carbon dioxide has largely gone and no dial-in will bring it back. Check the roast date on the bag before you touch the grinder.
Then grind and dose. Too coarse or under-dosed and the water runs through with too little resistance to emulsify anything, which gives a pale, fast shot with a crema that vanishes in seconds. Fine the grind a step and bring the dose up to your basket's rating.
Then pressure and temperature. A pump delivering well under nine bars, a worn group gasket bleeding pressure or a boiler running cool will all flatten crema. If beans are fresh and the grind is right, the machine is the next place to look.
Not automatically, but it is a reliable warning sign. Crema is a proxy for freshness and correct extraction, and it is worth reading rather than chasing for its own sake.
Past six to eight weeks from roast you will see crema drop off and the cup flatten. That is why we roast to order and deliver straight from our roastery.
Almost always under-extraction from a coarse grind or a light dose. Fine the grind, bring the dose to the basket rating and the crema will hold longer.
Yes, robusta produces more and more persistent crema, which is why traditional Italian style blends include a proportion of it. It changes the flavour too, so it is a blend decision rather than a fix.
Yes. Low pump pressure, a worn group gasket or a cool boiler all suppress crema even with perfect beans and a perfect grind.
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