Yes but the acid in the juice may cause the grains to disintegrate. You may alternate between fruit juice and sugar water to keep the grains healthy. Or the best way to kefir juice is to brew up a batch of water kefir, strain out the grains and then add the kefir water to the juice. Give that combo a couple of days to ferment and drink it when you like the taste. Start with 25% kefir to 75% juice and play with the ratios to find what you prefer.