為何咖啡烘焙愈深、油脂感愈好？油哪裏來的？ Why Does Coffee Have Better Crema with Dark Roasting and Where Does the Oil Come from?
咖啡豆表面出現油，是在烘焙過程中纖維結構內的脂質浮出表面形成的。咖啡豆表面的油帶有重要的風味物質，也對沖煮咖啡的口感產生重大影響。咖啡油脂是好是壞？
The appearance of oil on the surface of coffee beans occurs during the roasting process when lipids within the fibrous structure migrate to the surface. The oil on the surface of coffee beans carries essential flavor compounds and significantly influences the mouthfeel of brewed coffee. But is coffee oil good or bad?
咖啡生豆富含蛋白質、蔗糖、礦物質、綠原酸、纖維素、水和脂質等。在烘焙過程中因為加熱，每種物質都會發生不同的反應，從而導致一系列變化。這些變化中包含常聽到的梅納反應及焦糖化反應，另外重要的變化之一就是咖啡豆表面油的形成。
Coffee green beans contain proteins, sucrose, minerals, chlorogenic acids, cellulose, water, and lipids. During roasting, each of these substances undergoes different reactions due to the applied heat, leading to a series of changes. These changes include well-known processes like the Maillard reaction and caramelization. Another crucial change during roasting is the formation of oil on the surface of coffee beans.
咖啡豆表面油的形成是因為熱能破壞內部結構並變得多孔，油脂在烘焙時會被烘焙過程產生的二氧化碳擠到表面。烘焙時間越長，隨著豆子深層結構的分解，出現的油脂就越多。烘焙越深的咖啡豆重量會越輕，並有更多的油出現。
The formation of oil on coffee beans' surface is a result of the breakdown of the internal structure due to heat, making the beans porous. As the beans roast, the generated carbon dioxide pushes the lipids to the surface. The longer the roasting time, the more oil emerges as the internal structures of the beans decompose further. Deeper roasted coffee beans weigh less and contain more oil.
烘焙完成後才滲出來的油脂，是咖啡烘焙中剩餘的二氧化碳排出來時順便推擠出來的。烘焙後一個月內，咖啡豆仍會持續排出二氧化碳，剛烘焙後的前幾天排氣量特別多。這也就是淺焙咖啡在長時間儲存後也會出油，依豆體軟硬度不同，油會慢慢浮出表面。
The oil released after roasting is the residual carbon dioxide being pushed out, which also brings the oil to the surface. Within the first month after roasting, coffee beans continue to release carbon dioxide, with a particularly high rate in the first few days after roasting. This is why lightly roasted coffee can also develop an oily surface after extended storage, and depending on the bean's hardness, the oil slowly floats to the surface.
咖啡油脂在沖煮過後能讓口感飽滿厚重，帶有奶油感、濃稠感的品飲感受，因此選擇越深焙的咖啡、會有更佳的油脂感，雖然深焙的風味偏向單調，沒有花果調的香氣風味，但口感上的厚重感是一大特色。特別是以義式咖啡機煮濃縮咖啡時，咖啡油脂是最重要的部份。
Coffee oil adds a full and rich mouthfeel to the brewed coffee, providing a creamy and thick sensation. Hence, choosing deeper-roasted coffee can enhance the crema, even though deeply roasted coffees may lack the complex floral and fruity aromas found in lighter roasts, they offer a distinctive mellowness in mouthfeel. This is especially important when brewing espresso with an espresso machine, where coffee oil plays a crucial role.
一般來說，阿拉比卡生豆的脂質含量約為15%，高於羅布斯塔生豆的脂質含量約為10%；那為何傳統的義式配方豆要用羅布斯塔豆呢？而且傳說羅布斯塔豆的crema(濃縮咖啡油脂)較厚，但事實上油脂含量卻少於阿拉比卡豆。這是因為生長在低海拔的羅布斯塔豆的密度較低，在烘焙下容易逼出油脂；此外羅布斯塔豆的成本很低，有利於傳統的義式配方的商業用豆。因此，高品質的義式配方應該用阿拉比卡豆，有著更多脂質，也有更多糖份及各種風味物質。
In general, Arabica green beans contain around 15% lipids, whereas Robusta green beans contain around 10% lipids. So, why do traditional Italian espresso blends use Robusta beans? There is a misconception that Robusta beans produce a thicker crema (the concentrated coffee oil) compared to Arabica beans, when in fact, Robusta beans have less oil. This is because Robusta beans grown at lower altitudes have lower density and thus easily release oil during roasting. Additionally, Robusta beans are cheaper, making them more favorable for traditional Italian espresso blends. For high-quality Italian espresso blends, Arabica beans should be used for their higher lipid content, greater sweetness, and diverse flavor compounds.
有時候深焙會過分強化咖啡的特性，但需要有能夠承受深焙的生豆品質，否則只能品嚐到烘焙的味道。Tim Wendelboe曾說過，2004年世界咖啡師(World Barista Cup, WBC)冠軍，「無論是否深烘，88分的咖啡通常會比84分的咖啡味道更好。即使烤得很黑，高品質材料的味道仍然會比低品質材料好一點。」JC咖啡的義式配方是用高品質的阿拉比卡豆，風味豐富、口感厚實濃稠。
Sometimes, overemphasizing roasting can overpower the coffee's inherent qualities, but it requires high-quality beans that can withstand the deeper roasting. Tim Wendelboe, the winner of the 2004 World Barista Cup (WBC), once said, "Regardless of whether it's deeply roasted, an 88-point coffee usually tastes better than an 84-point coffee. Even if roasted very dark, the flavor of high-quality beans will still be slightly better than low-quality beans." Justin Coffee's Italian espresso blend is made with high-quality Arabica beans, offering a rich and robust flavor with a full-bodied and mellow mouthfeel.
雖然咖啡油脂有助於口感厚重，但隨著油脂而來的問題是氧化，烘焙結束後，咖啡豆就受到周圍空氣中氧氣的威脅，與豆子表面的油脂接觸會轉化為過氧化物，漸漸的導致產生酸敗、難聞的味道。所以意味著深焙咖啡應該比淺焙咖啡在烘焙後要更早飲用，以限制氧化的影響。
While coffee oil contributes to a full-bodied mouthfeel, it also brings oxidation issues. After roasting, coffee beans are exposed to oxygen in the surrounding air, and the contact between the beans' surface oil and oxygen leads to the formation of peroxides, resulting in undesirable acidic and off-flavors. This means that deep roasted coffee should be consumed earlier after roasting compared to lighter roasts to limit the impact of oxidation.
如果我們的需求是一杯味道濃郁厚實的咖啡，那麼帶有豐富油脂的深焙咖啡就是正確的選擇；如果我們的需求是細膩輕盈的咖啡，那麼帶有豐富花香、水果香的淺焙咖啡就是最佳選擇；如果我們需求的是口感適中滑順的咖啡，那麼帶有些許果香與堅果調的中焙咖啡就是很好選擇。試試不同口感的咖啡，感受其中有趣的感官體驗！
If our preference is for a rich and robust coffee, then a deep-roasted coffee with abundant oil is the right choice. For those seeking a delicate and light coffee, a lightly roasted coffee with floral and fruity aromas is ideal. And for those desiring a smooth and balanced coffee, a medium-roasted coffee with subtle fruit and nutty notes is an excellent option. Experimenting with different coffee flavors allows us to explore intriguing sensory experiences!
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