Some people like to make smoothies by putting veg and fruit in a blender, and blending away. Many people are also in a rush in the morning and want to make smoothies, and store some for a day or two. But when some vitamins are exposed to oxygen they start to break down, defeating the purpose of the smoothy.
But there is a solution!
I use a non-toxic wine preserver spray. It's $10usd but lasts for about 100 doses and it's really works. I put some smoothies in a glass jar with a rubber (not silicone) seal, then spray wine preserver in it. The spray is mostly nitrogen, with a bit of carbon dioxide and argon. It is heavier than air and prevents oxygen from getting to your smoothy. It also works on wine!
So...blend and spray!