第一次见到蓝色的蒜是在北餐厅的面条窗口，醋泡的蒜通常是蓝色的。我当时以为是蒜发霉了或者变质了。前几天在家包饺子，切了些蒜，干放着，不一会儿就干了，变成黄色，于是加了些水。也没怎么管，就放旁边了。过了一天，蒜的颜色变成了很淡的蓝色，我还以为眼睛花了。又过了一天，蒜变成了蓝色。闻之，无异味，食之也无异味。所以看来不是发霉，而是和蒜里的某种和物质有关。

上网查，百度知道（http://zhidao.baidu.com/question/22334308.html）说蒜酶其了重要作用，而醋酸能增加细胞膜的通透性，促进蒜变绿。而变绿是因为生成了蒜绿色素。看起来解释得头头是道，但对我的理解没有什么帮助，什么是“蒜绿色素”？

换成用英文查，在雅虎问答（http://answers.yahoo.com/question/index?qid=20071125134940AA7pLQl）上看到一个比较好的解释

“According to the Food Network at www.foodtv.com...they looked into the reason pickled garlic sometimes turns blue or green. Garlic contains anthocyanins, water-soluble pigments that turn blue, green or purple in an acid solution. While this color transformation tends to occur more often with immature garlic, it can differ among cloves within the same head of garlic. The garlic flavor remains unchanged, and it totally edible without bodily harm.

On the same subject, garlic contains sulfur compounds which can react with copper to form copper sulfate, a blue or blue-green compound. The amount of copper needed for this reaction is very small and is frequently found in normal water supplies. Raw garlic contains an enzyme that if not inactivated by heating reacts with sulfur (in the garlic) and copper (from water or utensils) to form blue copper sulfate.
”

看起来有两种解释，一种是蒜含有花青素，可以变成蓝色。另外一种解释是蒜含有硫化物，可以和铜反应生成硫酸铜，从而看起来是蓝色。而且所需要的铜的量很少，通常自来水里就含有足够的铜离子。

但是，怎么区分两种效应呢？我只想到，用蒸馏水做同样的使用，如果还是变蓝，可以确认第一种效应存在。但是在自来水的情况下是不是第二中效应也起作用就难以确认了。

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