What we have here is known most commonly as Brown Center or Hollow Heart, a concentration of sugar in the center of some potatoes occurring during growth, which creates a small, darkened cavity in the center. A variety of factors is thought to play a role in brown center and hollow heart development in potatoes. While the causes are not currently well understood, two theories are commonly proposed:

• The first suggests potato plant "stress," such as sudden changes in temperature, early in potato development can cause the plants to reabsorb water, minerals and carbohydrates back from the tubers themselves. Subsequent rapid potato growth may be the cause of hollow heart initiation.
• A second theory suggests that rapid tuber enlargement alone, without any stress, is enough to initiate hollow heart.

Brown center and hollow heart are more prevalent when the soil is cool and moist at the time of tuber initiation. Later planting dates and increased plant density tend to reduce the incidence of hollow heart. Other potential influences include bulking rate, tuber size and nitrogen application. Since brown center and hollow heart are growth problems, they are not initiated by disease organisms, nor are they transferred from one potato to another. Seed potatoes containing either characteristic will not pass them through to subsequent potato crops. Please note that potato taste, nutritional profile and solids content are not affected by hollow heart. In baked potatoes once opened simply use a fork or small spoon to remove the brown area before serving.

Here are a few pictures of Hollow Heart: