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Why size matters for top-quality coffee

With the average coffee drinker no longer content to sip on a cup of instant, ensuring consumers enjoy the highest possible quality of product is a priority for everyone from growers to wholesalers and retailers. 

It's for this reason that wholesalers and retailers need to make an effort to select only the best beans, often travelling the world in search of the finest flavours. However, when it comes to quality control, this is only part of the story. Just as important is screening – a near-exact science few consumers even know about, let alone appreciate. 

Quite simply, size matters. Beans are sorted through specially-made screens with holes of varying sizes. It may be cheap, low-tech and old-fashioned, but it is certainly effective. 

These screens retain some of the beans while allowing others to pass through the holes. Screens are graded according to the size of their holes, with a numeric system based on sixty-fouths of an inch, so screen size 15 has holes measuring just 15/64 of an inch across. 

While this numerical system may be the most common way of measuring screen size, it's by no means the only method. For instance in Africa and India, producers grade their biggest beans AA, with A, B and C screen grades indicating progressively-smaller screen sizes, while in Colombia, exporters will advertise beans that have been passed through the largest screens as Supremo, compared with the smaller Excelso beans.  

Whatever the grading system, the aim of screening is the same the world over: to ensure the quality is both high and, above all, consistent. Of course, a completely perfect product is virtually impossible and some discrepancies in bean size are to be expected. Nevertheless, if a buyer pays for a specific size of coffee bean, they expect to get it and screening will ensure this. 

The process may be time-consuming, with multiple screenings not uncommon, but the end result is worth the effort. A uniform size of bean makes for a more even roast, guaranteeing a consistent flavour. 

Some retailers, as well as some consumers, are firmly of the belief that larger beans make for tastier coffee. At the same time, however, too many big beans can complicate the roasting process, and so again, screening plays an essential role in maintaining the highest levels of quality control.