We recently started buying organic milk. The expiration date on the last carton we bought was over a month away so I thought it must have been an error. Well tonight we picked up another carton and I was surprised to see another expiration date almost six weeks away. I did a little google-ing and it turns out that organic milk uses a different pasteurizing process than regular milk. It is heated at a higher temperature and kills virtually all bacteria, allowing it to stay fresh for much longer. The downside is that it caramelizes some of the lactose resulting in a sweeter flavor, but since I pretty much only use milk on my cereal and in cooking I have never noticed the difference in flavor. Plus we always ended up throwing out half used cartons of regular milk, so in the long run I think the organic option will actually be saving us money!