"Rugbrod is like wine in France,

or olive oil in Italy.

It is more than food.

It is history. It is culture, and agriculture.

——Claus Meyer

上周跟大家介绍过冰岛用温泉烘焙的黑麦面包rúgbrauð，大家都觉得挺有意思，埋在地下温泉，制成后看着似巧克力蛋糕一样。

不过大部分的黑麦面包(Rugbrod/Rye Bread)在制作和口感上可没这么可爱。国内也几乎没有比较正统的黑麦面包，终其原因倒不在于种植少，而在于黑麦面包有股强大的酸味儿，也不似小麦或全麦面包那般松软。

正如资深纽约客Julia Moskin所言：“Any adventurous eater who has wandered into the woods of modern Nordic cuisine has probably tripped over a loaf of rye bread. ”确实，大部分人在尝试北欧美食时，都冷不丁被黑麦面包结实地“撂了个跟头”

“They can be as dark as chocolate cake and as spicy as gingerbread. They are often powerfully sour and even more powerfully delicious.”

人们被那股强大的酸味儿劝退，自然很多人也品不出那些爱吃之人所言的美味。然而即便这样，黑麦面包仍有大批忠实拥趸，在跨北欧5国以及德国等地，几乎是家家户户必备的主食，被尊为“国民面包”。黑麦面包的酸味，甚至那一点似有若无的苦味（the bitterness that comes from rye, and the edgy taste of the caramelized crust）都是当地爱好者心中的高级口感。

那么黑麦面包为什么会有酸味儿呢？

又为什么在德国和北欧盛行不衰呢？