Let me briefly explain what scientifically SAUERKRAUT is; then I will discuss on freezing effect. Making Sauerkraut, a Naturally fermented product: Sauerkraut is made from Cabbage through the fermentation naturally by several lactic acid bacteria. read more
So sauerkraut does not have bacteria that one can tale them to be probiotic, unless they are not telling the truth. Freezing sauerkraut, due to its low pH will kill the lactic acid bacteria rapidly ( than at room or refrigerated temperature), that are associated with fermentation of sauerkraut. read more