Good quality corn should have fresh green husks with silk ends that are free of decay or worms. Its ears should be evenly covered with plump, consistently sized kernels. Fresh corn on the cob will lose up to 40% of its sugar content after 6 hours of room temperature storage. The sugar is converted to starch. It is a good Source of the antioxidant Vitamin C. Refrigerate. Corn is highly perishable; eat as soon as possible.