是什么導(dǎo)致咖啡的澀味？

被稱為多酚的大分子，尤其是綠原酸（CGA）和丹寧酸，是沖煮咖啡中澀味的可能主要來源。多酚是大分子，與大多數(shù)其他咖啡可溶物相比，提取起來往往較不容易，盡管CGA似乎比單寧提取時(shí)更容易提取。（尚未科學(xué)證明CGA比單寧更容易提取，但似乎很可能。）很可能通過 滲濾式?jīng)_煮?沖煮的咖啡液提取物中發(fā)現(xiàn)了大多數(shù)收斂性多酚。由于缺乏 通道作用，浸泡式萃取 不太可能出現(xiàn)澀味。

是什么增加了沖煮出澀味的風(fēng)險(xiǎn)？

沖煮咖啡中澀味增加的幾種潛在來源：

• 生豆里面有未生長成熟的咖啡豆

• 烘焙發(fā)展不足

• 滲濾沖煮（手沖）過程中的通道效應(yīng)

未生長成熟的咖啡豆和發(fā)展不足的烘焙都傾向于在杯中產(chǎn)生更高程度的CGA。CGA既是收斂性多酚，也是咖啡中最普遍的酸。一杯適量的CGA對(duì)于一杯美味的杯子可能很重要（盡管我不確定我們是否有人嘗過沒有CGA的咖啡），但是當(dāng)CGA含量太高時(shí)，咖啡會(huì)變得很澀。

如何找到并修正澀源

當(dāng)我發(fā)現(xiàn)沖煮有澀味時(shí)，我將通過一系列步驟來查找和修正澀味的來源：

• 如果我曾經(jīng)用同一批烘焙的咖啡豆做出過沒有澀味的 滲濾式?jīng)_煮（手沖），則幾乎可以肯定最近的出品有澀味是由 通道效應(yīng) 引起。在這種情況下，我會(huì)（希望）使用更好的磨豆機(jī)進(jìn)行較粗研磨（相比這次）進(jìn)行再次沖煮。

• 如果我不能排除?通道效應(yīng)?的原因（例如，如果我不相信自己的沖泡方法或技能），我會(huì)對(duì)咖啡豆進(jìn)行杯測。如果杯測有澀味，則 通道效應(yīng) 不是 手沖 出現(xiàn)澀味的原因，或者至少不是唯一的原因。

• 如果 滲濾式?jīng)_煮 和 浸泡式?jīng)_煮（杯測）都產(chǎn)生澀味，則原因必須歸因于烘焙的發(fā)展不足或未成熟的咖啡豆。

• 如果所涉及的咖啡的某些烘焙批次具有澀味，而其他批次則沒有，則很可能是由烘焙過程的發(fā)展造成澀味的原因。

• 如果杯測完所有烘焙批次的豆子都有澀味，并 相信不是有烘焙的發(fā)展不足造成，那么 生豆 里面可能有未生長成熟的咖啡豆。

原文

WHAT CAUSES ASTRINGENCY IN COFFEE?

Large molecules called polyphenols, in particular chlorogenic acids (CGAs) and tannins, are the likely, primary sources of astringency in brewed coffee. Being larger molecules, polyphenols tend to extract less readily than most other coffee solubles, though CGAs seem to extract more readily than tannins do. (It has not been scientifically proven that CGAs extract more readily than tannins do, but it seems probable.) It’s likely the majority of astringent polyphenols found in brewed coffee extract via channeling in percolation brewing. Astringency is much less likely to occur in immersion brewing due to the lack of channeling.

WHAT INCREASES THE RISK OF AN ASTRINGENT BREW?

There are several potential sources of increased astringency in brewed coffee:

• beans (seeds) from underripe cherry*

• underdevelopment in roasting*

• channeling during percolation brewing

*Both underripe cherry and underdeveloped roasts tend to yield higher levels of CGAs in the cup. CGAs are both astringent polyphenols and also the most prevalent acids in coffee. Having some CGA is probably important for a delicious cup (though I’m not sure any of us have ever tasted a coffee without any CGAs), but when the CGA level is too high, the coffee becomes noticeably astringent.

HOW TO FIND AND FIX THE SOURCE OF ASTRINGENCY

When I find a brew astringent, I go through a series of steps to find and fix the source of the astringency:

• If I have previously made a non-astringent, percolation brew of the same roast batch of the coffee in question, it is almost certain that channeling caused the astringency in the more recent brew. In that case, I would brew again with either (hopefully) better technique of a coarser grind setting.

• If I cannot rule out channeling (for example, if I don’t trust my brewing method or skill), I will taste the coffee as a cupping. ?If the cupping is astringent, then channeling was not the cause, or at least not the only cause, of the astringency in the percolation brew.

• If both percolation and immersion (cupping) produced astringency, the cause must be due to an underdeveloped roast or underripe cherry.

• If some roast batches of the coffee in question are astringent and others aren’t, it is likely that roast development was the cause of the astringency.

• If all roast batches of the coffee are astringent when cupped, and you are confident they are not all underdeveloped, then the green was likely from underripe cherry.

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