Why are there xylem spirals in canned rhubarb but not fresh?

Xylem spirals in canned rhubarb are often more visible due to the cooking process during canning, which breaks down cell walls and makes the xylem structure more pronounced. In fresh rhubarb, the xylem is less noticeable because the plant's cells are intact and the fibrous structures are not as exposed. The canning process also softens the tissue, allowing the spirals to become more prominent. Thus, the difference is mainly a result of the physical and chemical changes during cooking.