Yet, although the composition of blends will inevitably reflect market conditions, notably price, they also have to respect customer tastes. These have developed in dialogue with each other over time, and continue to reflect not just the social and cultural mores of a society, but also its economic and political pasts. In the last three decades of the 19th century, for example, a devastating outbreak of coffee leaf rust destroyed most of the coffee production in Asia and Africa. These were replanted using the hardier robusta coffee plant which, however, has a bitter mouth taste compared to the original arabica coffee plant that remained the dominant species cultivated in Latin America.3 Those European states that sourced a significant share of their coffee supply from their African and Asian colonies became used to blends containing a higher robusta content, and corrected these for taste by utilising longer roasts at higher temperatures (often referred to as „French‟).

很多资料里提到19世纪末30年，即1870~1890 年遭过植物叶锈病危机，对亚非生长有毁灭性打击。这些地方以前种植硬度较高的罗豆，与在拉丁美洲种植占主导地位的比卡豆比起来，口感较苦。

从亚非殖民地获得很大一部分咖啡供应的欧洲国家已经习惯了拼配中罗豆含量较高的咖啡，利用高温较长时间的烘焙 （经常代指 法式烘焙 ）来纠正口感。

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