Physiological Disorders Blackheart. Insufficient oxygen reaches the interior of the tuber under these conditions. Non-pigmented compounds form in the vascular bundle tissue just under the skin during storage. Following severe bruising or cutting, the affected tuber tissue turns reddish, then blue becoming black in 24 to 72 hours. Severity increases with time.
Varieties differ significantly in their susceptibility and symptom expression.
Much longer periods of storage are generally required for chilling injury. Associated with greening, bitter and toxic glycoalkaloids, such as solanine, are formed. Glycoalkaloids are heat stable and minimally impacted by cooking. Internal Brown Spot. Internal dry, corky reddish-brown or black spots or sectors.