低因咖啡是怎麼製作出來的？會降低咖啡的口味么？

11-16

作為一個每天喝兩杯咖啡就開始出現反應的人來說，好想知道如何把自己喜歡的咖啡豆給decaf了？千萬不要告訴我靠稀釋啊～～！！！以及，從專業的角度看，decaf是否會導致口感的改變？
補充，我所謂的「反應」吧
其實我覺得我的心血管功能還是棒棒滴的。不喝咖啡還好，連續喝過2杯咖啡（特別是下午那杯咖啡）後，就會經歷一個從「興奮」到「神經抑制」的狀態，主要問題就是抑鬱，各種負情緒，懶懶得反而啥都不想動了～～咖啡因直接刺激了神經系統的耐受性，直接進入負反饋狀態……20點喝一大杯特濃22點就睡著的事情我會亂說。
本題已收錄進知乎圓桌 ? 喝杯好咖啡歡迎關注討論。

因為只了解瑞士水處理的脫因過程，所以就針對這個處理法回答題住，還好瑞士水處理脫因還是灰常灰常流行滴，全程只用到水，最終咖啡因含量含量低於乾重的0.1%，符合ICO對低因咖啡的定義，低於0.3%

生豆麻袋長下邊這個樣子~~

decaf確實是對生豆進行處理法處理的，所以要是足夠土豪，題主的願望還真的可以實現。

過程如下
給生豆洗個澡，浸泡在水中

可溶性物質溶解入水（包含咖啡風味類物質與咖啡因）

木質纖維，綠原酸等等不溶於水，保留在生豆內，析出咖啡因。

關鍵的賴磊，水中有個變態的咖啡因終結者，把溶解的咖啡因不斷的過濾掉，而溶液與生豆的濃度差也繼續幫助咖啡因溶解入水。

8~10小時後，咖啡生豆泡舒坦了，咖啡因也已經只剩0.1%

最後猜測應該是進行烘乾脫水。因為我手都有生豆，是這個樣子的

最後說一下風味，因為我也沒有條件跟精確同批次的未處理的生豆進行風味比對，主觀上來說水處理的咖啡豆body（體質感）相較近似產區的弱，略有澀味（可能是我烘焙的問題，因為這個含水量明顯不是很正常），風味的豐富程度較淡薄，沖泡後忘了用TDS測試，同等條件下是否水溶物會更低，主觀上喝起來感覺更淡些，如果TDS偏低可以用更高的粉水比彌補。所以題主希望低因又風味不變恐怕現在技術還沒發展到那步…………

書上看過介紹，正好用來答題——有三類方法去除咖啡因。去除咖啡因會降低咖啡口感。

答第一問：
一、歐式（溶劑）處理，有兩種細分。

直接溶劑法。蒸氣打開生豆孔，直接噴咖啡因溶劑，繼續用「蒸」的方式去除溶劑和咖啡因。
間接溶劑法。熱水浸泡生豆，把一切能泡的東西都泡出來。水豆分離。用溶劑取出熱水中的咖啡因，剩下的「味道」噴回淡而無味的豆子軀殼上……

二、瑞士水處理（敢死隊先犧牲，後來者有福啦處理法）。第一撥生豆泡熱水，能溶解的物質都溶入水中後，豆子扔掉。水中的咖啡因用碳濾方式去除，餘下「風味飽和的液體」。此後再往裡面加生豆，咖啡因會溶解，「風味們」就還留在豆子里。更棒的只要碳濾一下，咖啡因去除後的「風味飽和液」能繼續使用。

三、二氧化碳處理法。拿高壓之下呈半液態、半氣態的二氧化碳去結合生豆里的咖啡因，最後用碳濾方式去除咖啡因（這個方法我從書中看得似懂非懂，希望更有學識的知友來科普）。

答第二問：
咖啡因本身存在與否不影響咖啡口感，但去咖啡因的暴虐過程會有負面影響。

以上是我用大白話轉述的，追求嚴謹性的知友可以看下附原文。出處是Kenneth Davids大神的烘豆科普書Home Coffee Roasting, Revised, Updated Edition: Romance and Revival （2003）。

原文：
Coffees are decaffeinated in their green state. Three principal processes are used today in specialty coffees to remove caffeine: the traditional or European process, the water- only or Swiss- water process, and the CO 2 process. All are consistently successful in removing all but a trace (2 to 3 percent) of the resident caffeine.

The European or Solvent Process.There are two variants of the solvent method. The direct solvent process opens the pores of the beans by steaming them and applies the solvent directly to the beans before removing both solvent and caffeine by further steaming. The indirect solvent process first removes virtually everything, including the caffeine, from the beans by soaking them in hot water, then separates the beans and water and strips the caffeine from the flavor- laden water by means of the caffeine- attracting solvent. The solvent- laden caffeine is then skimmed from the surface of the water, and the water, now free of both caffeine and solvent, is reunited with the beans, which soak up the flavor components again.

The Swiss Water or Water- Only Process. In this commercially successful process there are two phases. In the first, start- up phase, green beans are soaked in hot water, which removes both flavor components and caffeine from the beans. This first, start- up batch of beans is then discarded, while the caffeine is stripped from the water by means of activated charcoal filters, leaving the flavor components behind in the water and producing what the Swiss water- process people call 「flavor- charged water」— water with the flavor but without the caffeine. This special water becomes the medium for the decaffeination of subsequent batches of green beans. When soaked in the flavor- charged but caffeine- free water, new batches of beans give up their caffeine but not their flavor components, which remain more or less intact in the bean. Apparently the water is so charged with flavor components that it can absorb no more of them, whereas it can absorb the villainous caffeine. Having thus been deprived of their caffeine but not their flavor components, the beans are then dried and sold, while the flavor- charged water is cleaned of its caffeine by another run through charcoal filters and sent back to decaffeinate another batch of beans.

The CO2 Process.In the CO2 method, the green beans are bathed in highly compressed carbon dioxide (CO2 ), the same naturally occurring substance that plants consume and human beings produce. In its compressed form the carbon dioxide behaves partly like a gas and partly like a liquid, and has the ability to combine selectively with caffeine. The caffeine is stripped from the CO2 by means of activated charcoal filters.

DECAFFEINATION AND FLAVOR
However powerfully it may affect our nervous systems, caffeine has very little effect on flavor. Isolated, it is a bitter, almost tasteless white powder. Coffee without it should taste virtually the same as coffee with it. Nevertheless, soaking green coffee beans in hot liquid and drying them out again is not a gentle process. It definitely affects the flavor of the abused beans. Affects how much? Depending on how careful the decaffeination process and how attentive the subsequent roasting, from a little to a lot. If you buy decaffeinated beans to roast at home you may notice that they are no longer the common gray- green to blue- green color of unroasted coffee, but instead range from a rather sallow yellow to a light brown. This color change is due to the soaking and drying to which the beans have been subjected during decaffeination. The result for roasting purposes is delicate beans that roast much less predictably than untreated beans. The combination of the loss of some flavor agents in the soaking process with the difficulty in roasting accounts for the fact that decaffeinated coffees purchased in the store may not taste as consistently good as coffee from untreated beans. The main message for the home roaster is to buy green decaffeinated beans from a reliable source, and roast them carefully. See Chapter 5 ( here ) and the instructions following that chapter for suggestions on handling decaffeinated coffees. You might also consider making blends of decaffeinated and untreated coffees. The untreated beans bolster the taste of the decaffeinated beans, yet still limit the amount of caffeine. Remember, however, that you may need to roast the decaffeinated beans in a separate session before blending, since they typically reach the same degree of roast 15 to 25 percent faster than untreated beans.

常見的咖啡脫咖啡因的方法有三種。

第一種是直接接觸法
這種方法一般使用二氯甲烷。這是一種比較常見的有機溶劑，他有較低的毒性。用二氯甲烷的溶液去浸泡咖啡生豆，是的豆子里的咖啡因成分溶解到溶劑中，從而從咖啡豆中脫離出來。最後去處咖啡豆這個時候溶液應該是不能完全去除的，會有一定的殘留。但是二氯甲烷的沸點很低（40度），很容易就可以聽過加熱去處殘留。況且這個溫度比咖啡烘焙的溫度低太多。所以國際上都比較認可直接接觸法的安全性。

第二種是瑞士水洗法
這種方法其他幾個答案都介紹的很專業很詳細了。
主要是通過已經充滿咖啡風味成分但是沒有咖啡因的風味水。新泡的豆子里的咖啡因就會向水中擴散，而風味不會流失。

第三種是自然脫咖啡因法
這種方法是通過日晒等方法使咖啡豆去處咖啡因。

其實低因咖啡是咖啡豆的一種特殊的加工方法，他的咖啡因含量在1%以下。在咖啡採摘，加工，烘焙，煮制的其他環節，他和非低因的豆子都沒有區別，只是加工生豆時多了一道工序。
從理論上來說，低因咖啡的風味都不應該流失。但是我的理解是，這並不表示同種的豆子，低因和非低因的喝起來就一模一樣（脫因了味道差別還是挺明顯的，特別是醇度下降很多）。只是說，如果這款豆子有草藥味，或者柑橘味，那麼低因的豆子也會同樣保持草藥味或者柑橘味。

憑著回憶用手機寫的，難免有錯漏，希望諒解。

脫咖啡因一共有三種，1.瑞士水洗法；2.二氯甲烷；3.直接接觸法。其中瑞士水洗法最為複雜，星巴克就是使用這種方法去除咖啡因。以上三種方法不會影響咖啡豆的風味，或者影響很小。有興趣可以在問我呀。

謝邀，我也只是了解其大致原理，詳細的並不很了解……這個問題已邀請@梁齊，他是食品加工行業專業人士，他的解答應該會比我更專業……
至於是否影響口味，據我喝過的低因來講，沒喝出太大的差別……

是的，咖啡因溶於水，是可溶解物質。其他的回答都很專業了，我就不回答了。不過我要補充的是不光咖啡里有咖啡因很多飲料和水果里也都含咖啡因。巧克力，咖啡，紅牛飲料，可樂飲料，茶都是含有咖啡因的，　要強調的是茶里的咖啡因有時被稱為茶因、茶色素。

低因咖啡味道比較清淡，香味不沖鼻，不太喜歡。還是喜歡正常的咖啡豆。其實每天幾杯咖啡的咖啡因對普通人來說，不存在危害，（特殊人群除外）。壓根兒沒必要。。。

我不是理論派，也不是專業派，親測的低因咖啡，可以嘗試下LUFE發酵咖啡，生豆是哥倫比亞阿拉比卡豆，經過深度清洗，生物發酵後有效降低了咖啡因，我們用未發酵的咖啡豆和發酵過的咖啡豆做過了實驗結果對比，發酵咖啡的咖啡因含量是普通咖啡的四分之一，檢測還顯示單寧酸含量也遠低於普通咖啡。經過發酵後，分解（低分子化）了導致咖啡苦澀和異味的物質，咖啡的味道更乾淨柔和。

曾經由於身體關係，只能喝低因的，幾乎嘗試了上海各個精品咖啡店的各種低因豆子。
個人體驗結果是：只要是低因的風味跟常規的咖啡都不能比坦白的說我覺得是差很多最後只能挑了一個相對來說風味保留得相對較好的。

個人感受，低因咖啡的口感比普通咖啡差了許多，普通人一天喝一兩杯，實際上咖啡因攝入非常有限，一杯espresso跟一瓶可樂的咖啡因含量估計差不了多少，適量的咖啡因攝入反而有益於身體（有一些書籍介紹，可減少心血管疾病、老年痴呆的發病概率）。低因咖啡主要為了滿足那些對咖啡因過度敏感（如心跳加快、失眠，身邊有好幾個朋友如此）但又喜歡咖啡的人群，真正喜歡咖啡的人，我想不會特別喜歡低因咖啡的味道。

一大早泡了個速溶忽然想起了decaf 過來看看點贊

星巴克的低咖啡因是有另外的豆子，本來就是低咖啡因豆子。