To store sweet potato chunks, place them in an airtight container and refrigerate them if they are already cooked. Cooked sweet potato chunks can last up to 4-5 days in the fridge. For raw sweet potato chunks, submerge them in a bowl of cold water to prevent browning, and store the bowl in the refrigerator for up to 2-3 days. Make sure to change the water daily to keep them fresh and ready for use.