No. When the PLANT experiences cold weather and/or frost or snow, it responds by adding sugar to its fluids. The sugar acts as an antifreeze to protect the veins, stems and leaves from freezing. WE like it because it makes the leaves sweeter but the plant could care less what we think. Your putting the leaves in the freezer has no effect on the plant because you've already picked the leaves. Dumping ice around the leaves would also have zero effect. It's the roots and stems which are sensing the cold and producing the sugar. IF you were raising Kale indoors or in a greenhouse in water ("Hydroponics"), you could chill the water down to 33 degrees and stimulate the Kale to produce the sugar. But that would be a very elaborate and expensive way just to get sweeter Kale and would hardly be worth it.
No. When the PLANT experiences cold weather and/or frost or snow, it responds by adding sugar to its fluids. The sugar acts as an antifreeze to protect the veins, stems and leaves from freezing. WE like it because it makes the leaves sweeter but the plant could care less what we think. Your putting the leaves in the freezer has no effect on the plant because you've already picked the leaves. Dumping ice around the leaves would also have zero effect. It's the roots and stems which are sensing the cold and producing the sugar. IF you were raising Kale indoors or in a greenhouse in water ("Hydroponics"), you could chill the water down to 33 degrees and stimulate the Kale to produce the sugar. But that would be a very elaborate and expensive way just to get sweeter Kale and would hardly be worth it.