The following spring my dad was visiting a farmer friend and his winter wheat was coming up. For the fun of it, he cut down a bunch and juiced it. He kept drinking it until he had finished a whole glass. Also the chlorophyll is much higher because it is in the sun. The simple sugars in the indoor sprouts cannot mature enough to change into complex carbohydrates, and that is why it is sweet like syrup.
Outdoor grass matures just before the jointing stage and creates a smooth grass taste.
It is in the ground for over 200 days compared with 7 - 10 days indoors. At great expense we now have an organic farm in Ontario, where we plant winter wheat and harvest it in the spring. We have about three weeks per year to do this. Lab reports show little change in the nutrients even after up to three years in the freezer. Freezing doesn't harm it, it is heat that does.