Which type of coffee processing is associated with the highest acidity?

The washed processing method is associated with the highest acidity in coffee. This processing technique involves removing the coffee cherry's outer fruit layer before the beans are fermented, leaving behind the mucilage. The fermentation process, typically done with water, helps to clean the beans and highlight the coffee's inherent flavors and acidity.

In washed coffees, the absence of the fruity pulp results in a cleaner taste profile that often accentuates bright acidity and clarity of flavors. This can lead to a more vibrant cup, which is often prized by coffee enthusiasts. The controlled fermentation process and thorough washing help to preserve the organic compounds that contribute to acidity, making washed coffees stand out in terms of brightness when compared to other processing methods.

Other processing techniques like semi-washed or natural can lead to different flavor profiles and acidity levels, but they tend to emphasize other attributes such as sweetness or fruitiness rather than the pronounced acidity found in washed coffees.