Grapes can be frozen and there are a number of ways to go about doing this. You will want to start off by purchasing at least a couple big bags of grapes with different colors. If possible you will want to get the seedless variety.
You will then need to wash the grapes you get, put them in a strainer, and then douse them with cold water so all pesticides and other chemicals are thoroughly removed. After you are done washing them, you will need to separate the grapes and remove all the stems. Take a cookie sheet and line it with paper towel, placing the grapes in single layers onto it.
Let the grapes dry for a while at room temperature and place the sheet in the freezer with the grapes on it. Allow all of the grapes on the sheet to freeze for at least a couple hours but not more than four, depending on the temperature of the freezer you are using. After this step has been completed, you will need to dip them in some granulated sugar while they are still wet from being washed.