Vegetables> Potato > Disorders

Black Heart

Black heart occurs in conditions of restricted airflow and high respiration especially where potatoes are stored in piles. Insufficient oxygen reaches the interior of the tuber under these conditions. Tubers held above 15°C (rapidly above 20°C) develop an internal brown discoloration, which eventually becomes deep black

Black Spot

It is responsible for significant postharvest losses, particularly in response to over-fertilization with nitrogen, low soil potassium availability, irregular irrigation, and other pre-harvest practices. Nonpigmented compounds are formed 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.

Greening

Exposure of tubers to bright light during postharvest handling, or longer periods (1 to 2 weeks) of low light intensity, can result in the development of greening in the potato tuber. Greening is associated with the formation of bitter and toxic glycoalkaloids, such as solanine. Solanine also forms in response to bruising, wounding (including fresh processing followed by storage), and during sprouting.

Freezing Injury

Potatoes when stored at temperatures near 0°C for a few weeks may result in a mahogany discoloration of internal tissue in some varieties. Symptoms of freezing injury include a watersoaked appearance, glassiness, and tissue breakdown on thawing.