effect of mechanical injury and low temperature storage on the accumulation of glycoalkaloids in the tubers of 7 varieties of potato (solanum tuberosum l.) grown in oman

Tubers from 7 potato varieties were analyzed for their rates of glycoalkaloid accumulation in response to stresses of three types of mechanical injury and low temperature storage. Mechanical injuries were found to greatly stimulate glycoalkaloid accumulation in both peel and flesh of tubers. The extent of glycoalkaloid accumulation appears to depend on variety, type of mechanical injury, and storage period. Most of the injury-stimulated glycoalkaloid accumulation occurred within 7 and 14 days after treatment. Cutting the tubers resulted in the highest content of glycoalkaloids both in flesh and peel up to levels that exceeded the upper safety limit of 200 mg/kg FW. Injury stimulated α-solanine accumulation in stored potato tubers is more than α-chaconine, resulting in a decrease in the α-chaconine: α-solanine ratio. When tubers were stored at low temperature, the rate of glycoalkaloid accumulation was found to be independent of the glycoalkaloid level at harvest. The greatest increase in total glycoalkaloid content of the seven varieties was found after two weeks of storage at both 4 ºC and 10 ºC. Further storage at these temperatures resulted in a decrease in the rate of glycoalkaloid accumulation in most of them. At 10 ºC glycoalkaloid content tended to increase more rapidly than at 4 ºC. The α-solanine content of the tubers showed an increase following low temperature storage.