If you haven’t cleaned out your refrigerator in a while, there might be a nasty surprise waiting for you. There, in a forgotten piece of Tupperware, lurks the ravioli you didn’t finish three weeks ago. Opening the lid with curiosity and fear, you’re confronted by a blue-green mess that only vaguely resembles pasta.

 

　　The lesson here seems to be that even when a jar or container is resealed and refrigerated, the food inside inevitably succumbs to a moldy end.

 

　　Actually, it depends on the food. For instance, when’s the last time you noticed that your honey had gone bad? Apparently, a jar of honey that’s been opened and resealed can stay on the shelf for years without going bad. Archaeologists have even found ancient jars with unspoiled honey inside.

 

　　So What’s The Secret To This Longevity?

 

　　Most food ferments when bacteria living in it eat sugars and nutrients in the food. The bacteria subsequently produce waste in the form of acids and other chemicals that affect the appearance, smell, and taste of the food. In other words, bacterial waste is what causes food to rot and appear moldy.

 

　　But like most life forms, bacteria need water to thrive. While many foods contain a good deal of water, honey contains almost none. What little water exists in honey binds to its sugars and enzymes, leaving little for bacterial growth. Unsealed, honey will attract water from the air and eventually ferment. But sealed, honey lasts for ages.

 

　　Of course, even sealed honey will eventually crystallize and turn hard, but this doesn’t mean it’s spoiled. In fact, even years later, it’s as good as new.

 

 

 

 

　　为什么蜂蜜不会变坏？

 

　　如果你有一段时间没有清理过你的冰箱了，那么里面脏乱的景象会让你大吃一惊。被遗忘的特百惠保鲜盒里放着三天前你没有吃完的饺子。你好奇又害怕地打开盖子，看到的是一团蓝绿色的脏乱的东西，看起来依稀有点像意大利面。

 

　　这似乎可以告诉我们，即使一个打开的罐子或容器被再次密封并且冷藏，里面的食物都会不可避免地会发霉。

 

　　实际上，会不会发霉取决于食物本身。例如，你最近一次发现你的蜂蜜变坏是什么时候？很明显，一罐打开过又重新密封的蜂蜜可以保存好几年而且不变质。考古学家们甚至发现古代罐子里装的蜂蜜仍未变质。

 

　　那蜂蜜的保质期能长期保存的秘密是什么呢？

 

　　大部分食物发酵是因为有细菌以这些食物的糖分和其它营养成分为食。接下来细菌代谢产生的废物会以酸和其他化学物质的方式存在并且影响食物的外观，气味和味道。换句话说，细菌的代谢物正是使食物腐烂和外观发霉的原因。

 

　　但是和许多生物一样，细菌需要水来繁殖。很多食物都含有大量水分，但是蜂蜜却几乎不含水分。蜂蜜中仅有的水分和糖分与酶结合在一起，几乎没水分提供给细菌生长。如果不被密封，蜂蜜会吸收空气中的水分，最后发酵。但是若密封起来，蜂蜜可保存好几年。

 

　　当然，即使是密封的蜂蜜最后也会结晶和变硬，但是这不代表变坏。实际上，即使数年以后，蜂蜜仍旧新鲜如初。